Figure 9 Figure 10 Why Choose Field Virus Field Virus

Why Choose Inactivated (Fixed antigen) Reproductive vaccines?Chris Chase Dr. Christopher Chase, ProfessorDepartment of Veterinary and Biomedical SciencesSouth Dakota State University (SDSU)

In the last 40 years, we have seen the “facts” of which type of vaccine, modified live vaccine (MLV) or inactivated (killed), are the most efficacious and safe, be hotly debated. In the 1970’s and 1980’s when MLV where first introduced, there were issues with MLV safety so inactivated vaccines was seen as a safer but not quite as efficacious vaccine. In the 1990’s and early 2000’s MLV vaccines were safer and their efficacy was superior to the old inactivated vaccines. Beginning in the late 1990’s improvements were made that begin improving the efficacy of inactivated vaccines. This improvement was driven by two factors: better quality antigens and improved adjuvants. The ability to grow viruses on cells in

bioreactors and gentler inactivation methods led to higher levels of “improved antigens” and improved immune responses. New and improved adjuvants were developed and used in veterinary vaccines. These adjuvants are the mixtures of molecules added to vaccines to make the immunity better and make the immune system work more efficiently to provide longer immunity (duration of protection). The discovery and development of better adjuvants was helped considerably by the work of researchers to develop HIV-AIDS vaccines. Although to this day, no human HIV-AIDS vaccine has been licensed, the HIV-AIDS work on adjuvants has made animal vaccines much better (Wilson-Welder 2009).

Modified Live vaccines - the Good, the Bad and the UglyModified live vaccines (MLV) have been used because of the broader and faster immune response, longer duration of immunity, fewer doses needed per animal and lower cost. These vaccines are administered intramuscular, intranasally or subcutaneously (Chase

Antigenic Mass -Modified-live VaccinesVaccine virus must replicate

Antigenic Mass-Inactivated Temperature Sensitive (Fixed antigen) Vaccines

Figure 2: Stress and MLV vaccines. MLV vaccines as they replication “infect” the animal. This results in both inflammation and immune suppression; 2a) Under heavy stress, animals have both high levels of inflammation and immune suppression so vaccinating with an MLV at these times is counterproductive. 2b) Under low stress the animals can respond to a MLV with a strong immune response.

STRESS

MLV

Immune

suppression

Inflammatory

response

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STRESS

MLV Immunity

Immune suppression

Inflammatory response

• The negative effects on the immune system that occur from virus infections can also occur at times of high stress because of a MLV application.

• Fixed antigen vaccines, unlike MLV, are no threat of causing reproductive effects.

• Fixed antigen vaccines also increase antibody titers to much higher levels which is important for colostral quality.

• The key to any good population immunity, allowed by mass vaccination with fixed antigen vaccines, is that a large enough percentatge of the animals (70-80%) develop good immunity so that the pathogen cannot spread easily in the herd.

1. Arthington JD, Cooke RF, Maddock TD, et al. Effects of vaccination on the acute-phase protein response and measures of performance in growing beef calves. J Anim Sci. 2013;91(4):1831-1837. doi:10.2527/jas.2012-5724.

2. Bitsch V. Infectious bovine rhinotracheitis virus infection in bulls, with special reference to preputial infection. Appl Microbiol. 1973;26(3):337-343.

3. Bosch JC, Kaashoek MJ, Van Oirschot JT. Inactivated bovine herpesvirus 1 marker vaccines are more efficacious in reducing virus excretion after reactivation than a live marker vaccine. Vaccine. 1997;15(14):1512-1517.

4. Chase C, Hurley DJ, Reber AJ. Neonatal Immune Development in the Calf and Its Impact on Vaccine Response. Veterinary Clinics of North America: Food Animal Practice. 2008;24(1):87-104. doi:10.1016/j.cvfa.2007.11.001.

5. Chase C, Arias Villegas N. Current concepts in dairy cattle vaccinology. In Proceedings of the American Association of Bovine Practitioners, Charlotte NC; 2016;49:89-94.

6. Chase C, Fulton RW, O’Toole D, et al. Bovine herpesvirus 1 modified live virus vaccines for cattle reproduction: Balancing protection with undesired effects. Veterinary Microbiology. 2017;206:69-77. doi:10.1016/j.vetmic.2017.03.016.

7. Grooms DL, Brock KV, Ward LA. Detection of cytopathic bovine viral diarrhea virus in the ovaries of cattle following immunization with a modified live bovine viral diarrhea virus vaccine. Journal of Veterinary Diagnostic Investigation. 1998;10(2):130-134. doi:10.1177/104063879801000202.

8. Kerkhofs P, Renjifo X, Toussaint JF, Letellier C, Vanopdenbosch E, Wellemans G. Enhancement of the immune response and virological protection of calves against bovine herpesvirus type 1 with an inactivated gE-deleted vaccine. Vet Rec. 2003;152(22):681-686.

9. Lippolis KD, Cooke RF, Schubach KM, et al. Altering the time

of vaccination against respiratory pathogens to enhance antibody response and performance of feeder cattle. J Anim Sci. 2016;94(9):3987-3995. doi:10.2527/jas.2016-0673.

10. McLean DJ, Chapman JD, Woolums A, Hurley DJ, Ely LO. Serum and colostrum antibody titers in Holstein cows, and the relationship between these titers and serum antibody titers in their calves. J Anim Sci. 2016;94(supplement5):49. doi:10.2527/jam2016-0105.

11. Palomares RA, Marley SM, Givens MD, Gallardo RA, Brock KV. Bovine viral diarrhea virus fetal persistent infection after immunization with a contaminated modified-live virus vaccine. Theriogenology. 2013;79(8):1184-1195. doi:10.1016/j.theriogenology.2013.02.017.

12. Pastoret P-P. Human and animal vaccine contaminations. Biologicals. 2010;38(3):332-334. doi:10.1016/j.biologicals.2010.02.015.

13. Platt R, Coutu C, Meinert T, Roth JA. Humoral and T cell-mediatedimmune responses to bivalent killed bovine viral diarrhea virus vaccine in beef cattle. Veterinary Immunology and Immunopathology. 2008;122(1-2):8-15. doi:10.1016/j.vetimm.2007.11.009.

14. Perry GA, Zimmerman AD, Daly RF, et al. The effects of vaccination on serum hormone concentrations and conception rates in synchronized naive beef heifers. Theriogenology. 2013;79(1):200-205. doi:10.1016/j.theriogenology.2012.10.005.

• We need to look at vaccines approaches that use non-abortifacient, non-latent bovine viral vaccines to develop lifelong immunity that will protect the animal while no harming the fetus.

• There is one double-deleted gE-/tk- MLV BHV-1 vaccine available in Europe that is non-abortifacient and does not establish latency (HIPRABOVIS IBR Marker Live).

HIPRAAvda. la Selva, 13517170 Amer (Girona)Spain

Tel.: +34 972 43 06 [email protected]

15. Perry GA, Larimore EL, Crosswhite MR, et al. Safety of Vaccinationwith an Inactivated or Modified Live Viral Reproductive Vaccine When Compared to Sterile Saline in Beef Cows. Jacobs Journal of Veterinary Science and Research. 2016;2(1):1-7.

16. Perry GA, Geary TW, Walker JA, et al. Influence of vaccination with a combined chemically altered/inactivated BHV-1/BVD vaccine or a modified live vaccine on reproductive performance in beef cows and heifers. J Anim Sci. 2017;95(supplement4):216. doi:10.2527/asasann.2017.440.

17. Raaperi K, Orro T, Viltrop A. Epidemiology and control of bovine herpesvirus 1 infection in Europe. Vet J. 2014;201(3):249-256. doi:10.1016/j.tvjl.2014.05.040.

18. Ridpath JF, Bayles DO, Neill JD, et al. Comparison of the breadth andcomplexity of bovine viral diarrhea (BVDV) populations circulating in 34 persistently infected cattle generated in one outbreak. Virology. 2015;485:297-304. doi:10.1016/j.virol.2015.07.022.

19. Rogers KC, Miles DG, Renter DG, Sears JE, Woodruff JL. Effects of delayed respiratory viral vaccine and/or inclusion of an immunostimulant on feedlot health, performance, and carcass merits of auction-market derived feeder heifers. The Bovine Practitioner. 2016;50(2):154-162.

20. Royan G. Comparison of the BVDV, BHV-1, and BRSV Anamnestic Response to Modified-live or Inactivated Vaccines in Calves Previously Vaccinated with a Modified-live Virus Vaccine. Bovine Practitioner. 2009;43(1):44-50.

21. Rodning SP, Marley MSD, Zhang Y, et al. Comparison of three commercial vaccines for preventing persistent infection with bovine viral diarrhea virus. Theriogenology. 2010;73(8):1154-1163. doi:10.1016/j.theriogenology.2010.01.017.

22. Stevens ET, Zimmerman AD, Butterbaugh RE, et al. The induction of a cell-mediated immune response to bovine viral diarrhea virus with an adjuvanted inactivated vaccine. Vet Ther. 2009;10(4):E1-E8.

23. Veerasami M, Chitra K, Mohana Subramanian B, ThamaraikannanP, Srinivasan VA, Dhinakar RG. Individual and Multiplex PCR Assays for the Detection of Adventitious Bovine and Porcine Viral Genome Contaminants in the Commercial Vaccines and Animal Derived RawMaterials. J Vet Sci Technol. 2014;05(03):1-6. doi:10.4172/2157-7579.1000179.

24. Walz PH, Givens MD, Rodning SP, et al. Evaluation of reproductiveprotection against bovine viral diarrhea virus and bovine herpesvirus-1afforded by annual revaccination with modified-live viral or combinationmodified-live/killed viral vaccines after primary vaccination with modified-live viral vaccine. Vaccine. 2017;35(7):1046-1054. doi:10.1016/j.vaccine.2017.01.006.

25. Walz PH, Montgomery T, Passler T, et al. Comparison of reproductiveperformance of primiparous dairy cattle following revaccination with either modified-live or killed multivalent viral vaccines in early lactation. Journal of Dairy Science. 2015;98(12):8753-8763. doi:10.3168/jds.2015-9760.

26. Wilson-Welder JH, Torres MP, Kipper MJ, et al. Vaccine adjuvants: current challenges and future approaches. J Pharm Sci. 2009;98(4):1278-1316. doi:10.1002/jps.21523

27. Zimmerman AD, Buterbaugh RE, Herbert JM, et al. Efficacy of bovine herpesvirus-1 inactivated vaccine against abortion and stillbirth inpregnant heifers. J Am Vet Med Assoc. 2007;231(9):1386-1389.

Key messages

References

More cattle will respond to an additonal dose of vaccine- Better protection and safer Fewer cattle will respond to an additonal dose of vaccine - Less protection and the susceptible andvariable protected animals at higher risk to vaccine safety problems

Figure 9 Figure 10

Revaccination of Herd with Fixed Antigen Booster Vaccine Revaccination of Herd with MLV Antigen

Vaccinated - no response on revaccination - Variable Protected


Not vaccinated or poor response to vaccination - Susceptible Not vaccinated or poor response to vaccination - Susceptible

Vaccinated - good response on revaccination -Well Protected


Field Virus Field Virus

5 6

Figure 1: Antigenic Mass and MLV vaccines. The MLV vaccine virus must replicate in the animal to generate antigenic mass.

Figure 3: Antigenic Mass and Fixed antigen vaccines. All the anti-gen must be in the vaccine to provide adequate antigenic mass.

ConclusionTimes have changed and so has the technology and research on the effectiveness of bovine viral vaccines. We understand that efficacy is more than protection against acute disease but equally as important is reproductive protection and safety. If “efficacy” means an increase in immune response and protection using only MLV vaccines to booster animals, then “efficacy” is not being achieved. If “safe” means “no abortions”, the present conventional parenteral bovine MLV vaccines are not “safe”. There should be a broader realization that with conventional MLV BHV-1 vaccines that reactivation of latent BHV-1 vaccine virus is likely occurring and contributing to reproductive disease. Finally, we need to look at vaccine approaches that use non-abortifacient, non-latent bovine viral vaccines to develop lifelong immunity that will protect the animal while doing no harm to the fetus.

2016). One of the major reasons that MLV are lower cost is that they rely on the animal to be the vaccine “production” machine to generate “antigenic mass” (Figure 1).

“Antigenic mass” is essential as a minimum quantity of antigen must be present to activate the immune system. When the virus in MLV replicates, it mimics “a mild natural infection”. There are three major safety concerns with MLV vaccines 1) immune dysfunction and disease, 2) mutations and 3) “adventitious” agents. Since the replication of MLV virus “mimics a real infection” the negative effects on the immune system that occurs from virus infections can also occur at times of high stress where MLV vaccines can enhance. These include an overactivation of the inflammatory response and/or immune suppression disease and increase mortality (Rogers 2016). These outcomes from MLV are really exaggerated if animals are under stress (Figure 2a). Stress can activate immune dysfunction by inducing the inflammatory response and immunosuppression (Arthington 2013; Lippolis 2016). This is why it is always best to vaccinate animals during times of low stress (Figure 2b) to induce a good immune response.Avoiding vaccination at stress points like weaning, calving, transportation will result in a better response to the vaccine and better health. At low stress, there is little immune dysfunction so the effect

from the MLV vaccine will be to induce immunity and not exacerbate disease. An additional issue with the “natural infection” is that the replicating virus will target susceptible body systems particularly the reproductive system. This is particularly true for infectious bovine rhinotracheitis [IBR; bovine herpesvirus-1 (BHV-1)] and bovine viral diarrhea (BVDV) viruses that affect reproductive structures in the ovaries including ovarian follicles and the corpus luteum (CL) (Grooms 1998: Perry 2013). This becomes critical in naïve and poorly vaccinated heifers or cows. These vaccines administered at the wrong time in poorly vaccinated females can result in reproductive losses that can range from poor conception rate to abortions (Perry 2013; Chase 2017). At the SDSU Diagnostic Laboratory in the US we have been sequencing the IBR abortion viruses since 2009 and all the viruses isolated appear to be vaccine viruses. Other studies have demonstrated 6-8% reduced first service conception in MLV vaccinated beef cattle when revaccinated with a MLV vaccine compared to an inactivated vaccine prior to breeding (Perry 2016).

Another issue of particular concern with BHV-1 vaccines is their ability to establish latency. These viruses establish latency in the immune and nervous system (Raaperi 2014). Latently infected animals should always be considered a potential source of infection (Bitsch, 1973), although vaccination can

considerably reduce the amount of virus excreted following reactivation (Bosch 1997; Kerkhofs 2003). Latently reactivated virus has been associated with abortion (Chase 2017). There is one double-deleted gE-/tk- MLV BHV-1 vaccine available in Europe that is non-abortifacient and does not establish latency (Raaperi 2014).

Another major concern with MLV virus is that mutations occur when the MLV virus replicates. For example, we know that every time BVDV replicates, there is at least one mutation that occurs. Most of these mutations have no effect on the ability of the virus to grow or how the animal responds to it but there is always some risk of new strains arising (Ridpath 2015). Finally, in these times of new and emerging viruses, MLV can also be contaminated with “adventitious agents” (Palomares 2016; Pastoret 2010; Veerasami 2014). These are usually viruses that contaminated some of the cells or media that was used to make the vaccine. With the new and advanced testing that we have for vaccines this is rare but it does happen.In particular, field strains of BVDV has been a frequent “adventitious agent” (Palomares 2016).

Fixed antigen vaccines - a safe and efficacious approachFixed antigen (inactivated vaccines and/or temperature sensitive injected

MLV Vaccine Response in the Naïve AnimalFigure 4

SkinHigh Endothelial Venule

LYMPH NODE

VirusReplicates

Lymphatic circulation


LYMPH NODE

Lymphatic circulation Virus

Replicates

Figure 4. MLV vaccine response in the naïve animal. The vaccine virus replicates and is recognized by the immune system. This results in antigen being transported to lymph nodes and generating an acquired immune response.Figure 5. Lack of MLV Vaccine Response in the Well-Protected Animal. The vaccine virus is recognized by and neutralized by pre-existing immunity to the vaccine. This results in no increase in antigenic mass and failure of antigen to be transported to lymph nodes and boostering an acquired immune response.

vaccines) contain live temperature sensitive, and/or chemically orphysically inactivated bacteria, toxins and/or viruses. These vaccines haveto contain sufficient antigenic mass to stimulate the immune system (Figure 3). One of the frequent complaints forthe use of inactivated vaccines is that two doses are required but with the advent of better antigen preparation and use of adjuvants results in significant adaptive immune responses after one dose (Platt 2008; Sandbulte 2003; Stevens 2009). Although thereis no danger of replication of the vaccine virus from any fixed antigenvaccine, only the inactivated vaccinesdo not contain live adventitious agents. Improved adjuvants have increased the scope and duration of inactivated vaccine immunity. Inactivated vaccinesgenerate cell-mediated responses (Platt 2008; Sandbulte 2003; Stevens2009) and protection (Bosch 1997; Kerhofs 2003; Herbert 2007). Interestingly there is ample evidencethat inactivated vaccines can effectively boost MLV vaccines (Grooms 2000;Royan 2009; Walz 2015; Walz 2017). In the face of clinical challenge, the reduction in clinical signs of BHV-1 are similar between MLV and inactivated vaccines but the level of BHV-1 shed isreduced by several logs with inactivated vaccines so spread of infectious virus

is reduced (Kerhofs 2003). Inactivatedvaccines also increase antibody titers to much higher levels, which is important for colostral antibody levels (McLean 2016; Royan 2009; Walz2015; Walz 2017).

Fixed antigen vaccines, unlike MLVare no threat of causing reproductive effects and improved conception ratesfollowing vaccination with fixed antigen vaccines (Perry 2016; Perry 2017). Inactivated vaccines also reduce the number of animals that secrete latent virus and the levels of virus that is produced (Bosch 1997; Kerhofs 2003).

Active InterferenceWhat is it and why should I care?As described earlier, “antigenic mass” is essential as a minimum quantity of antigen must be present to activate the immune system. Using a MLV innaïve low stressed animals results in a good immune response because “antigenic mass” is generated (Figure4). We know that maternal antibody can interfere (maternal interference) with MLV vaccines and result in apoor vaccine response (Chase 2008) (Figure 5). With maternal interference,this interference decreases over timeas the passive antibodies from the

colostrum disappear, so by 3-6 monthsthe animal will be able to fully respond. Once that animal develops its ownactive response, that immune response is life-long. One of issues with a “wellvaccinated animal” is that its immune system has been trained to eliminate the virus or the bacteria. The problem is the immune system can’t tell thedifference between the vaccine strainand the field or wild strain. Expecting that an animal repeatedly vaccinated with MLV will be boosted won’t happen. For a MLV to work, the vaccine organismhas to grow to a high enough level tofully activate all the steps need for a vaccine response (Figure 4). When the active immunity stops the vaccine organism from growing, that vaccineresponse can’t happen (Figure 5). This is also the issue we face with maternal interference, when colostral antibodiesfrom the cow “interfere” with the vaccine- the only difference is that the maternal antibodies decay or disappearwith time- not so with active immunity – these antibodies and immunity are produced by the animal and are therefor a life time.

As demonstrated by Walz et al, non-adjuvanted MLV vaccines failto booster well-vaccinated animals(Figures 6 and 7) (Walz 2017). Thevaccinated animals were all given two

Figure 6. BVDV-1 Titers following booster with MLV or inactivated vaccine. Red arrow indicates vaccination times. Green rectangle indicates the time of BVDV PI exposure. Blue arrow indicates BHV-1 intravenous challenge. MLV-modified live virus. From Walz PH, Givens MD, Rodning SP, et al. Vaccine. 2017;35(7):1046-1054. doi:10.1016/j.vaccine.2017.01.006Figure 7. BHV-1 Titers following booster with MLV or inactivated vaccine. Red arrow indicates vaccination times. Green rectangle indicates the time of BVDV PI exposure. Blue arrow indicates BHV-1 intravenous challenge. MLV-modified live virus; Fixed TS-temperature-sensitive. From Walz PH, Givens MD, Rodning SP, et al. Vaccine. 2017;35(7):1046-1054. doi:10.1016/j.vaccine.2017.01.006

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Day 0: First Vaccination Day 183: Second Vaccination Day 366: Third Vaccination Day 738: Fourth Vaccination Days 715-731: BVDV Exposure Day 830: BoHV-1 Inoculation

BVDV 1 Titers

Figure 6

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doses of MLV as calves. In the study, neither BVDV antibody titers (BVDV 2was similar-results not shown) aftertwo doses were not very high (~80 BVDV1; ~240 BVDV-2). Six months later, a third dose of vaccine either MLV or inactivated was given. The MLV group again had a low BVDV antibody response (~66 BVDV-1;~117 BVDV-2) that did not result ina measurable increase compared to the fixed antigen group (~456 BVDV-1; ~790 BVDV-2) (Figure 6). The animals were then exposed toBVDV persistently infected animals (Red rectangle). This resulted in an increase in antibody. There was an additional MLV or fixed antigenimmunization given at 738 days,which did not result in an antibody increase in the MLV group, which is not unusual following the short interval between natural challengeand the subsequent vaccination. A more dramatic effect was seen withIBR vaccination (Figure 6). Following the 2 two doses of MLV as calves, the titers were ~30 at highest. Following the vaccination with the third dose either MLV or fixed dose, the MLVboost was only ~20 while the fixedantigen was ~120. Active vaccineimmunity neutralizes vaccine virus preventing the MLV from replicating so there is no antigenic mass (Figure 7). The animal’s immunesystem can’t differentiate between a natural infection or vaccine virus and neutralizes the vaccine virus preventing the generation of antigenicmass and a booster response.

Together maybe betterBeginning in the 2000’s we had evidence that boosting animalsvaccinated with MLV with inactivatedvaccines resulted in higher antibody responses and also good cell immunity.This increase in antibody is really important for dry cows in the formation of colostrum since almost all of the antibody in colostrum comes right out of the serum of the animal. We also hadevidence that two doses of inactivatedinfectious bovine rhinotracheitis (IBR)vaccine could protect against abortion (Zimmerman 2007) but protection of two doses of bovine viral diarrhea virus (BVDV) inactivated vaccine wasn’tquite as good as MLV in preventing BVDV persistent infection (PI) (Rodning 2010). Recently there was a 3-yearstudy that showed animals first vaccinated with MLV and then boostedwith fixed antigen vaccine had fewer BVDV PIs and fewer IBR abortions than animals vaccinated and boosted with only MLV vaccines (Figure 8). In this study, all of the control animals either became BVDV PI animals or resultedin BHV-1 and/or BVDV abortions. The animals that were vaccinated only withMLV had better protection comparedto controls but there still was oneBVDV PI (1/ 23; 4%) and three BHV-1or BVDV abortions (3/23; 13%) (Figure 8). In contrast in the combination MLV-fixed antigen vaccine regimen, therewere no BVDV PI animals and the only abortion was not related to BHV-1orBVDV infections. This combinationresulted in better protection.

Enhancing Herd Immunity and Safety with Whole Herd Immunization ProgramsEven a “perfect” immune system in animals vaccinated with the “best vaccine” will not protect all the cattle. There will always be cattle that are susceptible (Figures 9 & 10). The key to any good herd vaccination program isthat a large enough percentage of the animals in herd develop good immunity(usually 70-80%) so that the pathogen cannot spread easily in the herd (Figures 9 & 10). This protection is referred to as “herd immunity”. Fixed antigen vaccines have the advantage that they can be given to the whole herd and a larger percentage will have a booster responseto the vaccine regardless of the stage of production (i.e. transition dairy cows, pregnant cows, breeding heifers) will have less impact on immune responsesince the dose of vaccine antigen is adequate (Walz 2015; Walz 2017) (Figure 9). On the other hand, very few animals revaccinated with a MLVvaccine will have a booster responsesince the MLV vaccine must grow tohave an adequate vaccine antigendose (Walz 2015; Walz 2017) (Figures 5 & 10). Since the MLV virus needs to replicate to get a good vaccine response and vaccine reproductive safety issues occur in animals where MLV replicates,vaccinating a whole herd with MLV willresult in animals being vaccinated at stages of production (i.e. pregnancy, breeding) where they are susceptible toeffects from the MLV. This may decreasethe conception rate and increase the abortion rate (Chase 2017).

433

Figure 8

Pregnant CowsGroup A MLV + MLV

Exposure to 6 BVDV PI cattle

BHV-1 IV Challenge+ 23 Total Calves - 19 Normal Calves, 3 Abortions

(1 BVDV, 2 BHV-1), 4 BVDV PI

Pregnant CowsGroup B MLV + Inactivated


BHV-1 IV Challenge+

Effect of Viral Infection on Confirmed Pregnancies and Newborn Calves

22 Total Calves - 21 Normal Calves, 1 Abortion, No virus

Adapted from Walz PH, Givens MD, Rodning SP, et al.Vaccine. 2017;35(7):1046-1054. doi:10.1016/j.vaccine.2017.01.006.

Figure 8.

The effect of reproductive challenge in vaccinated and control animals.

BVDV persistent infection

BHV-1

Abortion

BVDV + BHV-1

Pregnant CowsGroup C Control


BHV-1 IV Challenge+


15 Total Calves - 15 infected Calves, 11 Abortions (3 BVDV, 1 BHV-1, 7 both), 4 BVDV PI


2016). One of the major reasons that MLV are lower cost is that they rely on theanimal to be the vaccine “production” machine to generate “antigenic mass” (Figure 1).

“Antigenic mass” is essential as aminimum quantity of antigen must be present to activate the immune system. When the virus in MLVreplicates, it mimics “a mild naturalinfection”. There are three major safety concerns with MLV vaccines 1) immunedysfunction and disease, 2) mutationsand 3) “adventitious” agents. Sincethe replication of MLV virus “mimics a real infection” the negative effects on the immune system that occurs from virus infections can also occur at times of high stress where MLVvaccines can enhance. These include an overactivation of the inflammatory response and/or immune suppression disease and increase mortality (Rogers 2016). These outcomes from MLVare really exaggerated if animals are under stress (Figure 2a). Stress can activate immune dysfunction byinducing the inflammatory response and immunosuppression (Arthington 2013; Lippolis 2016). This is why itis always best to vaccinate animals during times of low stress (Figure 2b) to induce a good immune response.Avoiding vaccination at stress pointslike weaning, calving, transportation will result in a better response to the vaccine and better health. At low stress, there islittle immune dysfunction so the effect

from the MLV vaccine will be to induceimmunity and not exacerbate disease. An additional issue with the “natural infection” is that the replicating virus will target susceptible body systems particularly the reproductive system. This is particularly true for infectious bovine rhinotracheitis [IBR; bovine herpesvirus-1 (BHV-1)] and bovine viraldiarrhea (BVDV) viruses that affect reproductive structures in the ovaries including ovarian follicles and thecorpus luteum (CL) (Grooms 1998: Perry 2013). This becomes critical in naïve and poorly vaccinated heifers or cows. These vaccines administered at the wrong time in poorly vaccinated females can result in reproductive losses that can range from poor conception rate to abortions (Perry 2013; Chase 2017). At the SDSU Diagnostic Laboratory in the US we have been sequencing the IBR abortion viruses since 2009 and all the viruses isolated appear to be vaccine viruses. Other studies havedemonstrated 6-8% reduced first service conception in MLV vaccinated beef cattlewhen revaccinated with a MLV vaccine compared to an inactivated vaccine prior to breeding (Perry 2016).


considerably reduce the amount of virus excreted following reactivation (Bosch 1997; Kerkhofs 2003). Latently reactivated virus has been associated with abortion (Chase 2017). There is one double-deleted gE-/tk- MLV BHV-1vaccine available in Europe that is non-abortifacient and does not establish latency (Raaperi 2014).

Another major concern with MLV virus is that mutations occur when the MLVvirus replicates. For example, we knowthat every time BVDV replicates, there is at least one mutation that occurs. Most of these mutations have no effecton the ability of the virus to grow or howthe animal responds to it but there is always some risk of new strains arising(Ridpath 2015). Finally, in these times of new and emerging viruses, MLV can also be contaminated with “adventitious agents” (Palomares 2016; Pastoret 2010; Veerasami 2014). These areusually viruses that contaminated some of the cells or media that was usedto make the vaccine. With the new and advanced testing that we have for vaccines this is rare but it does happen.In particular, field strains of BVDV hasbeen a frequent “adventitious agent” (Palomares 2016).




LYMPH NODE

VirusReplicates



LYMPH NODE


Replicates

Figure 4. MLV vaccine response in the naïve animal. The vaccine virus replicates and is recognized by the immune system.This results in antigen being transported to lymph nodes and generating anacquired immune response.Figure 5. Lack of MLV Vaccine Response in the Well-Protected Animal. The vaccine virus is recognized by and neutralized by pre-existing immunity to the vaccine. This results in no increase in antigenicmass and failure of antigen to be transported to lymph nodes and boostering an acquired immune response.

vaccines) contain live temperature sensitive, and/or chemically or physically inactivated bacteria, toxins and/or viruses. These vaccines have to contain sufficient antigenic mass to stimulate the immune system (Figure 3). One of the frequent complaints for the use of inactivated vaccines is that two doses are required but with the advent of better antigen preparation and use of adjuvants results in significant adaptive immune responses after one dose (Platt 2008; Sandbulte 2003; Stevens 2009). Although there is no danger of replication of the vaccine virus from any fixed antigen vaccine, only the inactivated vaccines do not contain live adventitious agents. Improved adjuvants have increased the scope and duration of inactivated vaccine immunity. Inactivated vaccines generate cell-mediated responses (Platt 2008; Sandbulte 2003; Stevens 2009) and protection (Bosch 1997; Kerhofs 2003; Herbert 2007). Interestingly there is ample evidence that inactivated vaccines can effectively boost MLV vaccines (Grooms 2000; Royan 2009; Walz 2015; Walz 2017). In the face of clinical challenge, the reduction in clinical signs of BHV-1 are similar between MLV and inactivated vaccines but the level of BHV-1 shed is reduced by several logs with inactivated vaccines so spread of infectious virus

is reduced (Kerhofs 2003). Inactivated vaccines also increase antibody titers to much higher levels, which is important for colostral antibody levels (McLean 2016; Royan 2009; Walz 2015; Walz 2017).

Fixed antigen vaccines, unlike MLV are no threat of causing reproductive effects and improved conception rates following vaccination with fixed antigen vaccines (Perry 2016; Perry 2017). Inactivated vaccines also reduce the number of animals that secrete latent virus and the levels of virus that is produced (Bosch 1997; Kerhofs 2003).

Active Interference What is it and why should I care? As described earlier, “antigenic mass” is essential as a minimum quantity of antigen must be present to activate the immune system. Using a MLV in naïve low stressed animals results in a good immune response because “antigenic mass” is generated (Figure 4). We know that maternal antibody can interfere (maternal interference) with MLV vaccines and result in a poor vaccine response (Chase 2008) (Figure 5). With maternal interference, this interference decreases over time as the passive antibodies from the

colostrum disappear, so by 3-6 months the animal will be able to fully respond. Once that animal develops its own active response, that immune response is life-long. One of issues with a “well vaccinated animal” is that its immune system has been trained to eliminate the virus or the bacteria. The problem is the immune system can’t tell the difference between the vaccine strain and the field or wild strain. Expecting that an animal repeatedly vaccinated with MLV will be boosted won’t happen. For a MLV to work, the vaccine organism has to grow to a high enough level to fully activate all the steps need for a vaccine response (Figure 4). When the active immunity stops the vaccine organism from growing, that vaccine response can’t happen (Figure 5). This is also the issue we face with maternal interference, when colostral antibodies from the cow “interfere” with the vaccine- the only difference is that the maternal antibodies decay or disappear with time- not so with active immunity – these antibodies and immunity areproduced by the animal and are therefor a life time.

As demonstrated by Walz et al, non-adjuvanted MLV vaccines fail to booster well-vaccinated animals (Figures 6 and 7) (Walz 2017). The vaccinated animals were all given two


Geom

etric

Mea

n

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3000

2500

2000

1500

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00 100 200 300 400 500 600 700 800 900



BVDV PIExposure




BVDV 1 Titers

Figure 6


Group A

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2500

2000

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1000

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00 100 200 300 400 500 600 700 800 900

Group B Group G

BVDV PIExposure




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Figure 7

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doses of MLV as calves. In the study, neither BVDV antibody titers (BVDV 2was similar-results not shown) aftertwo doses were not very high (~80 BVDV1; ~240 BVDV-2). Six months later, a third dose of vaccine either MLV or inactivated was given. The MLV group again had a low BVDV antibody response (~66 BVDV-1;~117 BVDV-2) that did not result ina measurable increase compared to the fixed antigen group (~456 BVDV-1; ~790 BVDV-2) (Figure 6). The animals were then exposed toBVDV persistently infected animals (Red rectangle). This resulted in an increase in antibody. There was an additional MLV or fixed antigenimmunization given at 738 days,which did not result in an antibody increase in the MLV group, which is not unusual following the short interval between natural challengeand the subsequent vaccination. A more dramatic effect was seen withIBR vaccination (Figure 6). Following the 2 two doses of MLV as calves, the titers were ~30 at highest. Following the vaccination with the third dose either MLV or fixed dose, the MLVboost was only ~20 while the fixedantigen was ~120. Active vaccineimmunity neutralizes vaccine virus preventing the MLV from replicating so there is no antigenic mass (Figure 7). The animal’s immunesystem can’t differentiate between a natural infection or vaccine virus and neutralizes the vaccine virus preventing the generation of antigenicmass and a booster response.

Together maybe betterBeginning in the 2000’s we had evidence that boosting animalsvaccinated with MLV with inactivatedvaccines resulted in higher antibody responses and also good cell immunity.This increase in antibody is really important for dry cows in the formation of colostrum since almost all of the antibody in colostrum comes right out of the serum of the animal. We also hadevidence that two doses of inactivatedinfectious bovine rhinotracheitis (IBR)vaccine could protect against abortion (Zimmerman 2007) but protection of two doses of bovine viral diarrhea virus (BVDV) inactivated vaccine wasn’tquite as good as MLV in preventing BVDV persistent infection (PI) (Rodning 2010). Recently there was a 3-yearstudy that showed animals first vaccinated with MLV and then boostedwith fixed antigen vaccine had fewer BVDV PIs and fewer IBR abortions than animals vaccinated and boosted with only MLV vaccines (Figure 8). In this study, all of the control animals either became BVDV PI animals or resultedin BHV-1 and/or BVDV abortions. The animals that were vaccinated only withMLV had better protection comparedto controls but there still was oneBVDV PI (1/ 23; 4%) and three BHV-1or BVDV abortions (3/23; 13%) (Figure 8). In contrast in the combination MLV-fixed antigen vaccine regimen, therewere no BVDV PI animals and the only abortion was not related to BHV-1orBVDV infections. This combinationresulted in better protection.

Enhancing Herd Immunity and Safety with Whole Herd Immunization ProgramsEven a “perfect” immune system in animals vaccinated with the “best vaccine” will not protect all the cattle. There will always be cattle that are susceptible (Figures 9 & 10). The key to any good herd vaccination program isthat a large enough percentage of the animals in herd develop good immunity(usually 70-80%) so that the pathogen cannot spread easily in the herd (Figures 9 & 10). This protection is referred to as “herd immunity”. Fixed antigen vaccines have the advantage that they can be given to the whole herd and a larger percentage will have a booster responseto the vaccine regardless of the stage of production (i.e. transition dairy cows, pregnant cows, breeding heifers) will have less impact on immune responsesince the dose of vaccine antigen is adequate (Walz 2015; Walz 2017) (Figure 9). On the other hand, very few animals revaccinated with a MLVvaccine will have a booster responsesince the MLV vaccine must grow tohave an adequate vaccine antigendose (Walz 2015; Walz 2017) (Figures 5 & 10). Since the MLV virus needs to replicate to get a good vaccine response and vaccine reproductive safety issues occur in animals where MLV replicates,vaccinating a whole herd with MLV willresult in animals being vaccinated at stages of production (i.e. pregnancy, breeding) where they are susceptible toeffects from the MLV. This may decreasethe conception rate and increase the abortion rate (Chase 2017).

42

Figure 8







BHV-1 IV Challenge+



Adapted from Walz PH, Givens MD, Rodning SP, et al.Vaccine. 2017;35(7):1046-1054. doi:10.1016/j.vaccine.2017.01.006.

Figure 8.



BHV-1

Abortion

BVDV + BHV-1



BHV-1 IV Challenge+




2016). One of the major reasons that MLV are lower cost is that they rely on theanimal to be the vaccine “production” machine to generate “antigenic mass” (Figure 1).

“Antigenic mass” is essential as aminimum quantity of antigen must be present to activate the immune system. When the virus in MLVreplicates, it mimics “a mild naturalinfection”. There are three major safety concerns with MLV vaccines 1) immunedysfunction and disease, 2) mutationsand 3) “adventitious” agents. Sincethe replication of MLV virus “mimics a real infection” the negative effects on the immune system that occurs from virus infections can also occur at times of high stress where MLVvaccines can enhance. These include an overactivation of the inflammatory response and/or immune suppression disease and increase mortality (Rogers 2016). These outcomes from MLVare really exaggerated if animals are under stress (Figure 2a). Stress can activate immune dysfunction byinducing the inflammatory response and immunosuppression (Arthington 2013; Lippolis 2016). This is why itis always best to vaccinate animals during times of low stress (Figure 2b) to induce a good immune response.Avoiding vaccination at stress pointslike weaning, calving, transportation will result in a better response to the vaccine and better health. At low stress, there islittle immune dysfunction so the effect

from the MLV vaccine will be to induceimmunity and not exacerbate disease. An additional issue with the “natural infection” is that the replicating virus will target susceptible body systems particularly the reproductive system. This is particularly true for infectious bovine rhinotracheitis [IBR; bovine herpesvirus-1 (BHV-1)] and bovine viraldiarrhea (BVDV) viruses that affect reproductive structures in the ovaries including ovarian follicles and thecorpus luteum (CL) (Grooms 1998: Perry 2013). This becomes critical in naïve and poorly vaccinated heifers or cows. These vaccines administered at the wrong time in poorly vaccinated females can result in reproductive losses that can range from poor conception rate to abortions (Perry 2013; Chase 2017). At the SDSU Diagnostic Laboratory in the US we have been sequencing the IBR abortion viruses since 2009 and all the viruses isolated appear to be vaccine viruses. Other studies havedemonstrated 6-8% reduced first service conception in MLV vaccinated beef cattlewhen revaccinated with a MLV vaccine compared to an inactivated vaccine prior to breeding (Perry 2016).


considerably reduce the amount of virus excreted following reactivation (Bosch 1997; Kerkhofs 2003). Latently reactivated virus has been associated with abortion (Chase 2017). There is one double-deleted gE-/tk- MLV BHV-1vaccine available in Europe that is non-abortifacient and does not establish latency (Raaperi 2014).

Another major concern with MLV virus is that mutations occur when the MLVvirus replicates. For example, we knowthat every time BVDV replicates, there is at least one mutation that occurs. Most of these mutations have no effecton the ability of the virus to grow or howthe animal responds to it but there is always some risk of new strains arising(Ridpath 2015). Finally, in these times of new and emerging viruses, MLV can also be contaminated with “adventitious agents” (Palomares 2016; Pastoret 2010; Veerasami 2014). These areusually viruses that contaminated some of the cells or media that was usedto make the vaccine. With the new and advanced testing that we have for vaccines this is rare but it does happen.In particular, field strains of BVDV hasbeen a frequent “adventitious agent” (Palomares 2016).




LYMPH NODE

VirusReplicates



LYMPH NODE


Replicates

Figure 4. MLV vaccine response in the naïve animal. The vaccine virus replicates and is recognized by the immune system.This results in antigen being transported to lymph nodes and generating anacquired immune response.Figure 5. Lack of MLV Vaccine Response in the Well-Protected Animal. The vaccine virus is recognized by and neutralized by pre-existing immunity to the vaccine. This results in no increase in antigenicmass and failure of antigen to be transported to lymph nodes and boostering an acquired immune response.

vaccines) contain live temperature sensitive, and/or chemically orphysically inactivated bacteria, toxins and/or viruses. These vaccines haveto contain sufficient antigenic mass to stimulate the immune system (Figure 3). One of the frequent complaints forthe use of inactivated vaccines is that two doses are required but with the advent of better antigen preparation and use of adjuvants results in significant adaptive immune responses after one dose (Platt 2008; Sandbulte 2003; Stevens 2009). Although thereis no danger of replication of the vaccine virus from any fixed antigenvaccine, only the inactivated vaccinesdo not contain live adventitious agents. Improved adjuvants have increased the scope and duration of inactivated vaccine immunity. Inactivated vaccinesgenerate cell-mediated responses (Platt 2008; Sandbulte 2003; Stevens2009) and protection (Bosch 1997; Kerhofs 2003; Herbert 2007). Interestingly there is ample evidencethat inactivated vaccines can effectively boost MLV vaccines (Grooms 2000;Royan 2009; Walz 2015; Walz 2017). In the face of clinical challenge, the reduction in clinical signs of BHV-1 are similar between MLV and inactivated vaccines but the level of BHV-1 shed isreduced by several logs with inactivated vaccines so spread of infectious virus

is reduced (Kerhofs 2003). Inactivatedvaccines also increase antibody titers to much higher levels, which is important for colostral antibody levels (McLean 2016; Royan 2009; Walz2015; Walz 2017).

Fixed antigen vaccines, unlike MLVare no threat of causing reproductive effects and improved conception ratesfollowing vaccination with fixed antigen vaccines (Perry 2016; Perry 2017). Inactivated vaccines also reduce the number of animals that secrete latent virus and the levels of virus that is produced (Bosch 1997; Kerhofs 2003).

Active InterferenceWhat is it and why should I care?As described earlier, “antigenic mass” is essential as a minimum quantity of antigen must be present to activate the immune system. Using a MLV innaïve low stressed animals results in a good immune response because “antigenic mass” is generated (Figure4). We know that maternal antibody can interfere (maternal interference) with MLV vaccines and result in apoor vaccine response (Chase 2008) (Figure 5). With maternal interference,this interference decreases over timeas the passive antibodies from the

colostrum disappear, so by 3-6 monthsthe animal will be able to fully respond. Once that animal develops its ownactive response, that immune response is life-long. One of issues with a “wellvaccinated animal” is that its immune system has been trained to eliminate the virus or the bacteria. The problem is the immune system can’t tell thedifference between the vaccine strainand the field or wild strain. Expecting that an animal repeatedly vaccinated with MLV will be boosted won’t happen. For a MLV to work, the vaccine organismhas to grow to a high enough level tofully activate all the steps need for a vaccine response (Figure 4). When the active immunity stops the vaccine organism from growing, that vaccineresponse can’t happen (Figure 5). This is also the issue we face with maternal interference, when colostral antibodiesfrom the cow “interfere” with the vaccine- the only difference is that the maternal antibodies decay or disappearwith time- not so with active immunity – these antibodies and immunity are produced by the animal and are therefor a life time.

As demonstrated by Walz et al, non-adjuvanted MLV vaccines failto booster well-vaccinated animals(Figures 6 and 7) (Walz 2017). Thevaccinated animals were all given two


Geom

etric

Mea

n

Day of Study

3000

2500

2000

1500

1000

500

00 100 200 300 400 500 600 700 800 900



BVDV PIExposure




BVDV 1 Titers

Figure 6


Group A

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2000

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1000

500

00 100 200 300 400 500 600 700 800 900

Group B Group G

BVDV PIExposure




BHV-1 Titers

Figure 7

Geom

etric

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doses of MLV as calves. In the study, neither BVDV antibody titers (BVDV 2 was similar-results not shown) after two doses were not very high (~80 BVDV1; ~240 BVDV-2). Six months later, a third dose of vaccine either MLV or inactivated was given. The MLV group again had a low BVDV antibody response (~66 BVDV-1; ~117 BVDV-2) that did not result in a measurable increase compared to the fixed antigen group (~456 BVDV-1; ~790 BVDV-2) (Figure 6). The animals were then exposed to BVDV persistently infected animals (Red rectangle). This resulted in an increase in antibody. There was an additional MLV or fixed antigen immunization given at 738 days, which did not result in an antibody increase in the MLV group, which is not unusual following the short interval between natural challenge and the subsequent vaccination. A more dramatic effect was seen with IBR vaccination (Figure 6). Following the 2 two doses of MLV as calves, the titers were ~30 at highest. Following the vaccination with the third dose either MLV or fixed dose, the MLV boost was only ~20 while the fixed antigen was ~120. Active vaccine immunity neutralizes vaccine virus preventing the MLV from replicating so there is no antigenic mass (Figure 7). The animal’s immune system can’t differentiate between a natural infection or vaccine virus and neutralizes the vaccine virus preventing the generation of antigenic mass and a booster response.

Together maybe betterBeginning in the 2000’s we had evidence that boosting animals vaccinated with MLV with inactivated vaccines resulted in higher antibody responses and also good cell immunity. This increase in antibody is really important for dry cows in the formation of colostrum since almost all of the antibody in colostrum comes right out of the serum of the animal. We also had evidence that two doses of inactivated infectious bovine rhinotracheitis (IBR) vaccine could protect against abortion (Zimmerman 2007) but protection of two doses of bovine viral diarrhea virus (BVDV) inactivated vaccine wasn’t quite as good as MLV in preventing BVDV persistent infection (PI) (Rodning 2010). Recently there was a 3-year study that showed animals first vaccinated with MLV and then boosted with fixed antigen vaccine had fewer BVDV PIs and fewer IBR abortions than animals vaccinated and boosted with only MLV vaccines (Figure 8). In this study, all of the control animals either became BVDV PI animals or resulted in BHV-1 and/or BVDV abortions. The animals that were vaccinated only with MLV had better protection compared to controls but there still was one BVDV PI (1/ 23; 4%) and three BHV-1 or BVDV abortions (3/23; 13%) (Figure 8). In contrast in the combination MLV-fixed antigen vaccine regimen, there were no BVDV PI animals and the only abortion was not related to BHV-1or BVDV infections. This combination resulted in better protection.

Enhancing Herd Immunity and Safety with Whole Herd Immunization ProgramsEven a “perfect” immune system in animals vaccinated with the “best vaccine” will not protect all the cattle. There will always be cattle that are susceptible (Figures 9 & 10). The key to any good herd vaccination program is that a large enough percentage of the animals in herd develop good immunity (usually 70-80%) so that the pathogen cannot spread easily in the herd (Figures 9 & 10). This protection is referred to as “herd immunity”. Fixed antigen vaccines have the advantage that they can be given to the whole herd and a larger percentage will have a booster response to the vaccine regardless of the stage of production (i.e. transition dairy cows, pregnant cows, breeding heifers) will have less impact on immune response since the dose of vaccine antigen is adequate (Walz 2015; Walz 2017) (Figure 9). On the other hand, very few animals revaccinated with a MLV vaccine will have a booster response since the MLV vaccine must grow to have an adequate vaccine antigen dose (Walz 2015; Walz 2017) (Figures 5 & 10). Since the MLV virus needs to replicate to get a good vaccine response and vaccine reproductive safety issues occur in animals where MLV replicates, vaccinating a whole herd with MLV will result in animals being vaccinated at stages of production (i.e. pregnancy, breeding) where they are susceptible to effects from the MLV. This may decrease the conception rate and increase the abortion rate (Chase 2017).

32 3

Figure 8







BHV-1 IV Challenge+



Adapted from Walz PH, Givens MD, Rodning SP, et al. Vaccine. 2017;35(7):1046-1054. doi:10.1016/j.vaccine.2017.01.006.

Figure 8.



BHV-1

Abortion

BVDV + BHV-1



BHV-1 IV Challenge+





In the last 40 years, we have seenthe “facts” of which type of vaccine, modified live vaccine (MLV) orinactivated (killed), are the mostefficacious and safe, be hotly debated. In the 1970’s and 1980’s when MLVwhere first introduced, there were issues with MLV safety so inactivatedvaccines was seen as a safer butnot quite as efficacious vaccine. In the 1990’s and early 2000’s MLV vaccines were safer and their efficacywas superior to the old inactivatedvaccines. Beginning in the late 1990’simprovements were made that begin improving the efficacy of inactivatedvaccines. This improvement wasdriven by two factors: better quality antigens and improved adjuvants.The ability to grow viruses on cells in

bioreactors and gentler inactivation methods led to higher levels of“improved antigens” and improved immune responses. New and improved adjuvants were developed and used in veterinary vaccines. These adjuvantsare the mixtures of molecules added to vaccines to make the immunitybetter and make the immune system work more efficiently to provide longer immunity (duration of protection). The discovery and development of betteradjuvants was helped considerablyby the work of researchers to developHIV-AIDS vaccines. Although to this day, no human HIV-AIDS vaccine hasbeen licensed, the HIV-AIDS work on adjuvants has made animal vaccines much better (Wilson-Welder 2009).

Modified Live vaccines - the Good, the Badand the UglyModified live vaccines (MLV) have been used because of the broader and faster immune response, longer durationof immunity, fewer doses needed per animal and lower cost. These vaccinesare administered intramuscular, intranasally or subcutaneously (Chase




STRESS

MLV

Immune

suppression

Inflammatory

response

Immunity

STRESS

MLV Immunity

Immunesuppression


1

• The negative effects on the immune system that occur fromvirus infections can also occur at times of high stress becauseof a MLV application.

• Fixed antigen vaccines, unlike MLV, are no threat of causingreproductive effects.

• Fixed antigen vaccines also increase antibody titers to muchhigher levels which is important for colostral quality.

• The key to any good population immunity, allowed by massvaccination with fixed antigen vaccines, is that a large enoughpercentatge of the animals (70-80%) develop good immunityso that the pathogen cannot spread easily in the herd.

1. Arthington JD, Cooke RF, Maddock TD, et al. Effects of vaccination on the acute-phase protein response and measures of performance in growing beef calves. J Anim Sci. 2013;91(4):1831-1837. doi:10.2527/jas.2012-5724.

2. Bitsch V. Infectious bovine rhinotracheitis virus infection in bulls, with special reference to preputial infection. Appl Microbiol. 1973;26(3):337-343.

3. Bosch JC, Kaashoek MJ, Van Oirschot JT. Inactivated bovine herpesvirus 1 marker vaccines are more efficacious in reducing virus excretion after reactivation than a live marker vaccine. Vaccine. 1997;15(14):1512-1517.

4. Chase C, Hurley DJ, Reber AJ. Neonatal Immune Development in the Calf and Its Impact on Vaccine Response. Veterinary Clinics of North America: Food Animal Practice. 2008;24(1):87-104. doi:10.1016/j.cvfa.2007.11.001.

5. Chase C, Arias Villegas N. Current concepts in dairy cattle vaccinology. In Proceedings of the American Association of Bovine Practitioners, Charlotte NC; 2016;49:89-94.

6. Chase C, Fulton RW, O’Toole D, et al. Bovine herpesvirus 1 modified live virus vaccines for cattle reproduction: Balancing protection with undesired effects. Veterinary Microbiology. 2017;206:69-77. doi:10.1016/j.vetmic.2017.03.016.

7. Grooms DL, Brock KV, Ward LA. Detection of cytopathic bovine viral diarrhea virus in the ovaries of cattle following immunization with a modified live bovine viral diarrhea virus vaccine. Journal of Veterinary Diagnostic Investigation. 1998;10(2):130-134. doi:10.1177/104063879801000202.

8. Kerkhofs P, Renjifo X, Toussaint JF, Letellier C, Vanopdenbosch E, Wellemans G. Enhancement of the immune response and virological protection of calves against bovine herpesvirus type 1 with an inactivated gE-deleted vaccine. Vet Rec. 2003;152(22):681-686.


of vaccination against respiratory pathogens to enhance antibody response and performance of feeder cattle. J Anim Sci. 2016;94(9):3987-3995. doi:10.2527/jas.2016-0673.

10. McLean DJ, Chapman JD, Woolums A, Hurley DJ, Ely LO. Serum and colostrum antibody titers in Holstein cows, and the relationship between these titers and serum antibody titers in their calves. J Anim Sci. 2016;94(supplement5):49. doi:10.2527/jam2016-0105.

11. Palomares RA, Marley SM, Givens MD, Gallardo RA, Brock KV. Bovine viral diarrhea virus fetal persistent infection after immunization with a contaminated modified-live virus vaccine. Theriogenology. 2013;79(8):1184-1195. doi:10.1016/j.theriogenology.2013.02.017.

12. Pastoret P-P. Human and animal vaccine contaminations. Biologicals. 2010;38(3):332-334. doi:10.1016/j.biologicals.2010.02.015.

13. Platt R, Coutu C, Meinert T, Roth JA. Humoral and T cell-mediatedimmune responses to bivalent killed bovine viral diarrhea virus vaccine in beef cattle. Veterinary Immunology and Immunopathology. 2008;122(1-2):8-15. doi:10.1016/j.vetimm.2007.11.009.

14. Perry GA, Zimmerman AD, Daly RF, et al. The effects of vaccination on serum hormone concentrations and conception rates in synchronized naive beef heifers. Theriogenology. 2013;79(1):200-205. doi:10.1016/j.theriogenology.2012.10.005.

• We need to look at vaccines approaches that use non-abortifacient, non-latent bovine viral vaccines to developlifelong immunity that will protect the animal while no harmingthe fetus.

• There is one double-deleted gE-/tk- MLV BHV-1 vaccineavailable in Europe that is non-abortifacient and does notestablish latency (HIPRABOVIS IBR Marker Live).



15. Perry GA, Larimore EL, Crosswhite MR, et al. Safety of Vaccinationwith an Inactivated or Modified Live Viral Reproductive Vaccine When Compared to Sterile Saline in Beef Cows. Jacobs Journal of Veterinary Science and Research. 2016;2(1):1-7.

16. Perry GA, Geary TW, Walker JA, et al. Influence of vaccination with a combined chemically altered/inactivated BHV-1/BVD vaccine or a modified live vaccine on reproductive performance in beef cows and heifers. J Anim Sci. 2017;95(supplement4):216. doi:10.2527/asasann.2017.440.

17. Raaperi K, Orro T, Viltrop A. Epidemiology and control of bovine herpesvirus 1 infection in Europe. Vet J. 2014;201(3):249-256. doi:10.1016/j.tvjl.2014.05.040.

18. Ridpath JF, Bayles DO, Neill JD, et al. Comparison of the breadth andcomplexity of bovine viral diarrhea (BVDV) populations circulating in 34 persistently infected cattle generated in one outbreak. Virology. 2015;485:297-304. doi:10.1016/j.virol.2015.07.022.

19. Rogers KC, Miles DG, Renter DG, Sears JE, Woodruff JL. Effects of delayed respiratory viral vaccine and/or inclusion of an immunostimulant on feedlot health, performance, and carcass merits of auction-market derived feeder heifers. The Bovine Practitioner. 2016;50(2):154-162.

20. Royan G. Comparison of the BVDV, BHV-1, and BRSV Anamnestic Response to Modified-live or Inactivated Vaccines in Calves Previously Vaccinated with a Modified-live Virus Vaccine. Bovine Practitioner. 2009;43(1):44-50.

21. Rodning SP, Marley MSD, Zhang Y, et al. Comparison of three commercial vaccines for preventing persistent infection with bovine viral diarrhea virus. Theriogenology. 2010;73(8):1154-1163. doi:10.1016/j.theriogenology.2010.01.017.

22. Stevens ET, Zimmerman AD, Butterbaugh RE, et al. The induction of a cell-mediated immune response to bovine viral diarrhea virus with an adjuvanted inactivated vaccine. Vet Ther. 2009;10(4):E1-E8.

23. Veerasami M, Chitra K, Mohana Subramanian B, ThamaraikannanP, Srinivasan VA, Dhinakar RG. Individual and Multiplex PCR Assays for the Detection of Adventitious Bovine and Porcine Viral Genome Contaminants in the Commercial Vaccines and Animal Derived RawMaterials. J Vet Sci Technol. 2014;05(03):1-6. doi:10.4172/2157-7579.1000179.

24. Walz PH, Givens MD, Rodning SP, et al. Evaluation of reproductiveprotection against bovine viral diarrhea virus and bovine herpesvirus-1afforded by annual revaccination with modified-live viral or combinationmodified-live/killed viral vaccines after primary vaccination with modified-live viral vaccine. Vaccine. 2017;35(7):1046-1054. doi:10.1016/j.vaccine.2017.01.006.

25. Walz PH, Montgomery T, Passler T, et al. Comparison of reproductiveperformance of primiparous dairy cattle following revaccination with either modified-live or killed multivalent viral vaccines in early lactation. Journal of Dairy Science. 2015;98(12):8753-8763. doi:10.3168/jds.2015-9760.

26. Wilson-Welder JH, Torres MP, Kipper MJ, et al. Vaccine adjuvants: current challenges and future approaches. J Pharm Sci. 2009;98(4):1278-1316. doi:10.1002/jps.21523

27. Zimmerman AD, Buterbaugh RE, Herbert JM, et al. Efficacy of bovine herpesvirus-1 inactivated vaccine against abortion and stillbirth inpregnant heifers. J Am Vet Med Assoc. 2007;231(9):1386-1389.

Key messages

References

More cattle will respond to an additonal dose of vaccine- Better protection and safer Fewer cattle will respond to an additonal dose of vaccine - Less protection and the susceptible and variable protected animals at higher risk to vaccine safety problems

Figure 9 Figure 10








6





In the last 40 years, we have seenthe “facts” of which type of vaccine, modified live vaccine (MLV) orinactivated (killed), are the mostefficacious and safe, be hotly debated. In the 1970’s and 1980’s when MLVwhere first introduced, there were issues with MLV safety so inactivatedvaccines was seen as a safer butnot quite as efficacious vaccine. In the 1990’s and early 2000’s MLV vaccines were safer and their efficacywas superior to the old inactivatedvaccines. Beginning in the late 1990’simprovements were made that begin improving the efficacy of inactivatedvaccines. This improvement wasdriven by two factors: better quality antigens and improved adjuvants.The ability to grow viruses on cells in

bioreactors and gentler inactivation methods led to higher levels of“improved antigens” and improved immune responses. New and improved adjuvants were developed and used in veterinary vaccines. These adjuvantsare the mixtures of molecules added to vaccines to make the immunitybetter and make the immune system work more efficiently to provide longer immunity (duration of protection). The discovery and development of betteradjuvants was helped considerablyby the work of researchers to developHIV-AIDS vaccines. Although to this day, no human HIV-AIDS vaccine hasbeen licensed, the HIV-AIDS work on adjuvants has made animal vaccines much better (Wilson-Welder 2009).

Modified Live vaccines - the Good, the Badand the UglyModified live vaccines (MLV) have been used because of the broader and faster immune response, longer durationof immunity, fewer doses needed per animal and lower cost. These vaccinesare administered intramuscular, intranasally or subcutaneously (Chase




STRESS

MLV

Immune

suppression

Inflammatory

response

Immunity

STRESS

MLV Immunity

Immunesuppression


1

• The negative effects on the immune system that occur from virus infections can also occur at times of high stress because of a MLV application.

• Fixed antigen vaccines, unlike MLV, are no threat of causing reproductive effects.

• Fixed antigen vaccines also increase antibody titers to much higher levels which is important for colostral quality.

• The key to any good population immunity, allowed by mass vaccination with fixed antigen vaccines, is that a large enough percentatge of the animals (70-80%) develop good immunity so that the pathogen cannot spread easily in the herd.

1. Arthington JD, Cooke RF, Maddock TD, et al. Effects of vaccination onthe acute-phase protein response and measures of performance ingrowing beef calves. J Anim Sci. 2013;91(4):1831-1837. doi:10.2527/jas.2012-5724.

2. Bitsch V. Infectious bovine rhinotracheitis virus infection in bulls, withspecial reference to preputial infection. Appl Microbiol. 1973;26(3):337-343.

3. Bosch JC, Kaashoek MJ, Van Oirschot JT. Inactivated bovine herpesvirus1 marker vaccines are more efficacious in reducing virus excretion afterreactivation than a live marker vaccine. Vaccine. 1997;15(14):1512-1517.

4. Chase C, Hurley DJ, Reber AJ. Neonatal Immune Development in theCalf and Its Impact on Vaccine Response. Veterinary Clinics of NorthAmerica: Food Animal Practice. 2008;24(1):87-104. doi:10.1016/j.cvfa.2007.11.001.

5. Chase C, Arias Villegas N. Current concepts in dairy cattle vaccinology.In Proceedings of the American Association of Bovine Practitioners,Charlotte NC; 2016;49:89-94.

6. Chase C, Fulton RW, O’Toole D, et al. Bovine herpesvirus 1 modifiedlive virus vaccines for cattle reproduction: Balancing protectionwith undesired effects. Veterinary Microbiology. 2017;206:69-77.doi:10.1016/j.vetmic.2017.03.016.

7. Grooms DL, Brock KV, Ward LA. Detection of cytopathic bovineviral diarrhea virus in the ovaries of cattle following immunizationwith a modified live bovine viral diarrhea virus vaccine. Journalof Veterinary Diagnostic Investigation. 1998;10(2):130-134.doi:10.1177/104063879801000202.

8. Kerkhofs P, Renjifo X, Toussaint JF, Letellier C, Vanopdenbosch E,Wellemans G. Enhancement of the immune response and virologicalprotection of calves against bovine herpesvirus type 1 with aninactivated gE-deleted vaccine. Vet Rec. 2003;152(22):681-686.


of vaccination against respiratory pathogens to enhanceantibody response and performance of feeder cattle. J Anim Sci.2016;94(9):3987-3995. doi:10.2527/jas.2016-0673.

10. McLean DJ, Chapman JD, Woolums A, Hurley DJ, Ely LO. Serum andcolostrum antibody titers in Holstein cows, and the relationship betweenthese titers and serum antibody titers in their calves. J Anim Sci.2016;94(supplement5):49. doi:10.2527/jam2016-0105.

11. Palomares RA, Marley SM, Givens MD, Gallardo RA, Brock KV. Bovineviral diarrhea virus fetal persistent infection after immunizationwith a contaminated modified-live virus vaccine. Theriogenology.2013;79(8):1184-1195. doi:10.1016/j.theriogenology.2013.02.017.

12. Pastoret P-P. Human and animal vaccine contaminations. Biologicals.2010;38(3):332-334. doi:10.1016/j.biologicals.2010.02.015.

13. Platt R, Coutu C, Meinert T, Roth JA. Humoral and T cell-mediatedimmune responses to bivalent killed bovine viral diarrhea virusvaccine in beef cattle. Veterinary Immunology and Immunopathology.2008;122(1-2):8-15. doi:10.1016/j.vetimm.2007.11.009.

14. Perry GA, Zimmerman AD, Daly RF, et al. The effects of vaccination onserum hormone concentrations and conception rates in synchronizednaive beef heifers. Theriogenology. 2013;79(1):200-205. doi:10.1016/j.theriogenology.2012.10.005.

• We need to look at vaccines approaches that use non-abortifacient, non-latent bovine viral vaccines to develop lifelong immunity that will protect the animal while no harming the fetus.

• There is one double-deleted gE-/tk- MLV BHV-1 vaccine available in Europe that is non-abortifacient and does not establish latency (HIPRABOVIS IBR Marker Live).



15. Perry GA, Larimore EL, Crosswhite MR, et al. Safety of Vaccinationwith an Inactivated or Modified Live Viral Reproductive Vaccine WhenCompared to Sterile Saline in Beef Cows. Jacobs Journal of VeterinaryScience and Research. 2016;2(1):1-7.

16. Perry GA, Geary TW, Walker JA, et al. Influence of vaccination witha combined chemically altered/inactivated BHV-1/BVD vaccine ora modified live vaccine on reproductive performance in beef cowsand heifers. J Anim Sci. 2017;95(supplement4):216. doi:10.2527/asasann.2017.440.

17. Raaperi K, Orro T, Viltrop A. Epidemiology and control of bovineherpesvirus 1 infection in Europe. Vet J. 2014;201(3):249-256.doi:10.1016/j.tvjl.2014.05.040.

18. Ridpath JF, Bayles DO, Neill JD, et al. Comparison of the breadth andcomplexity of bovine viral diarrhea (BVDV) populations circulating in34 persistently infected cattle generated in one outbreak. Virology.2015;485:297-304. doi:10.1016/j.virol.2015.07.022.

19. Rogers KC, Miles DG, Renter DG, Sears JE, Woodruff JL. Effectsof delayed respiratory viral vaccine and/or inclusion of animmunostimulant on feedlot health, performance, and carcass meritsof auction-market derived feeder heifers. The Bovine Practitioner.2016;50(2):154-162.

20. Royan G. Comparison of the BVDV, BHV-1, and BRSV AnamnesticResponse to Modified-live or Inactivated Vaccines in Calves PreviouslyVaccinated with a Modified-live Virus Vaccine. Bovine Practitioner.2009;43(1):44-50.

21. Rodning SP, Marley MSD, Zhang Y, et al. Comparison of threecommercial vaccines for preventing persistent infection with bovine viraldiarrhea virus. Theriogenology. 2010;73(8):1154-1163. doi:10.1016/j.theriogenology.2010.01.017.

22. Stevens ET, Zimmerman AD, Butterbaugh RE, et al. The induction of acell-mediated immune response to bovine viral diarrhea virus with anadjuvanted inactivated vaccine. Vet Ther. 2009;10(4):E1-E8.

23. Veerasami M, Chitra K, Mohana Subramanian B, ThamaraikannanP, Srinivasan VA, Dhinakar RG. Individual and Multiplex PCR Assaysfor the Detection of Adventitious Bovine and Porcine Viral GenomeContaminants in the Commercial Vaccines and Animal Derived RawMaterials. J Vet Sci Technol. 2014;05(03):1-6. doi:10.4172/2157-7579.1000179.

24. Walz PH, Givens MD, Rodning SP, et al. Evaluation of reproductiveprotection against bovine viral diarrhea virus and bovine herpesvirus-1afforded by annual revaccination with modified-live viral or combinationmodified-live/killed viral vaccines after primary vaccination withmodified-live viral vaccine. Vaccine. 2017;35(7):1046-1054.doi:10.1016/j.vaccine.2017.01.006.

25. Walz PH, Montgomery T, Passler T, et al. Comparison of reproductiveperformance of primiparous dairy cattle following revaccination witheither modified-live or killed multivalent viral vaccines in early lactation.Journal of Dairy Science. 2015;98(12):8753-8763. doi:10.3168/jds.2015-9760.

26. Wilson-Welder JH, Torres MP, Kipper MJ, et al. Vaccine adjuvants:current challenges and future approaches. J Pharm Sci.2009;98(4):1278-1316. doi:10.1002/jps.21523

27. Zimmerman AD, Buterbaugh RE, Herbert JM, et al. Efficacy of bovineherpesvirus-1 inactivated vaccine against abortion and stillbirth inpregnant heifers. J Am Vet Med Assoc. 2007;231(9):1386-1389.

Key messages

References

More cattle will respond to an additonal dose of vaccine- Better protection and safer Fewer cattle will respond to an additonal dose of vaccine - Less protection and the susceptible andvariable protected animals at higher risk to vaccine safety problems

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Figure 9 Figure 10 Why Choose Field Virus Field Virus