Comparative Immunology, Microbiology and Infectious Diseases 33 (2010) e1–e5

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Comparative Immunology, Microbiologyand Infectious Diseases

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Efficacy of different protocols of vaccination against porcine circovirustype 2 (PCV2) in a farm affected by postweaning multisystemic wastingsyndrome (PMWS)

Zygmunt Pejsak a,*, Katarzyna Podgorska a, Marian Truszczynski a,Paweł Karbowiak b, Tomasz Stadejek a

a National Veterinary Research Institute, Swine Diseases Department, Partyzantow 57, 24-100 Pulawy, Polandb Vet-Com, Jagiellonska 71, 10-237 Olsztyn, Poland

A R T I C L E I N F O

Article history:

Accepted 21 September 2009

Keywords:

PMWS

PCVD

PCV2 vaccination

Vaccination programs

Circovac1

A B S T R A C T

In order to control growing problems associated with porcine circovirus type 2 (PCV2)

several vaccines for piglets or sows were introduced recently. An objective of the study

was to compare an efficacy of three different vaccination protocols in the herd with acute

postweaning multisystemic wasting syndrome (PMWS) outbreak affecting 3-month-old

pigs. All of three applied protocols, namely vaccination of sows, piglets or sows and piglets

with Circovac proved to be efficacious in controlling of PMWS. All production parameters

significantly improved after vaccination. Obtained values were as good as before the

outbreak or even better as in case of average daily weight gains. However, decreased

mortality before weaning was recorded only after vaccination of sows while in groups

where piglets were vaccinated significantly lower mortality in fourth month of life was

observed. The impact of different protocols on different parameters suggests that they

could be adopted in herds with different porcine circovirus associated problems.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Postweaning multisystemic wasting syndrome (PMWS)is a multifactorial disease syndrome affecting pigs world-wide. Porcine circovirus type 2 (PCV2) is recognized as anessential causative agent of this disease. PCV2 has beenassociated with systemic infection, respiratory diseases,enteritis, reproductive failures and, although no unequi-vocal evidence does exist, porcine dermatitis and nephro-pathy syndrome [1]. These conditions are often referred toas porcine circovirus diseases (PCVD) [9]. Piglets are incontact with the virus very early in life, probably as soon asborn. While they are protected by maternally derivedimmunity, the pigs are exposed to various amounts ofPCV2. The virus enters the piglet body and is captured by

* Corresponding author. Tel.: +48 81 8893030; fax: +48 81 8893346.

E-mail address: zpejsak@piwet.pulawy.pl (Z. Pejsak).

0147-9571/$ – see front matter � 2009 Elsevier Ltd. All rights reserved.

doi:10.1016/j.cimid.2009.09.006

various cells including epithelial cells [8], macrophagesand dendritic cells [14]. In dendritic cells PCV2 may persistfor very long time [13] escaping degradation and furtherprocessing by the immune system. It has been extensivelydemonstrated that piglets born from PCV2 viraemic sows[2] and piglets born from sows with weak PCV2 immunity[2,11] were at higher risk to develop PCVD any time in theirlife. Calsamiglia et al. [2] examined 105 randomly selectedsows and their offspring. The risk of PMWS in the offspringof 33 sows (31.4%) with low level of antibodies (titre atIPMA�1/20) was 3 times higher compared to the offspringof 72 sows (68.6%) with medium to high level of antibodies(titre between 1/320 and 1/20,480). Together with otherstudies [7] this indicates that in affected farms neonatesare exposed to higher PCV2 loads during the first weeks oftheir life. A recent comprehensive review gathering all 48available artificial challenge trials involving PCV2 alone orPCV2 associated with diverse chemical, viral and bacterialco-factors, re-established that it has been impossible to

Table 1

Experimental groups.

Number

of sows

Number

of piglets

Vaccination

program

Before PMWS outbreak 651 6894 No

During PMWS outbreak 628 6169 No

Z. Pejsak et al. / Comparative Immunology, Microbiology and Infectious Diseases 33 (2010) e1–e5e2

induce PMWS in pigs older than 6 weeks of age [12]. Thisimplies that the specific root of PCVD is likely to lie withthose early first weeks of the piglet life when immuneimpairment may take place. Later in life, as pigs are hit bydifferent co-factors, e.g. infections, stresses, inflamma-tions, while maternal derived immunity is slowly waning,the silent PCV2 can be reactivated. In some pigs that havebeen markedly immuno-compromised, a high level ofPCV2 multiplication, excretion and spreading into theenvironment occurs and some pigs may be very sick anddie, some may develop PCVD and survive while some otherpigs are only sub-clinically affected to various degrees.Consequently to this high level of shedding, all pen matesare re-exposed, become viraemic and then seroconvert.

The strategy of vaccinal protection against PCV2 shouldconsist in protecting the immune system of the pigs intheir early life against a massive exposure to PCV2 that ispotentially leading to an impairment of an immunesystem. Further in life, the pigs with a mature and non-damaged immune system as they are iteratively re-exposed to PCV2, will mount a long lasting protectiveactive immune response.

In order to control growing problems associated withPCV2 vaccination of sows with Circovac11 has beensuccessfully introduced in the field [5,6]. However, insome cases, as (i) when difficulties prevent from vaccinat-ing the sows (multi-source finishing units), (ii) inemergency vaccination to cover piglets the dams of whichwere not vaccinated, or (iii) in case of defects in husbandrypractices as non-sufficient colostrum management, anddue to the initial lack of registered products with thespecific piglet target indication, this vaccine was also usedin piglets.

The objective of the present study was to compare theclinical efficacy of different PCV2 vaccination programsusing criteria that directly impact the economical balancein a farm affected with acute PMWS.

2. Materials and methods

The study was conducted in a farrow-to-finish opera-tion suffering from an acute outbreak of PMWS. The farmwas chosen because of particularly high quality of the datarecording system based on Pigtales software (PIC).

The reproductive herd consisted of 2550 sows and 30boars. Strict all-in/all-out regime was maintained in thefarrowing, nursery and fattening units. Every week batch of100–110 pregnant sows was introduced into three farrow-ing houses. Piglets used to be weaned at 28 days of life andthen transferred into nursery units. At about 90 days (3months) of life they were moved to the fattening units. Pigswere slaughtered in a slaughterhouse belonging to the farmat about 92–100 kg of weight, depending on the batch.

The following pathogens were detected in pigs on thefarm on different occasions: PCV2, Mycoplasma hyopneu-

moniae, Bordetella bronchiseptica, dermonecrotoxic strainsof Pasteurella multocida, Actinobacillus pleuropneumoniae,Haemophilus parasuis, Streptococcus suis type 2. All sows

1 Circovac is a registered trademark of Merial in the USA and elsewhere.

were vaccinated against porcine parvovirosis, erysipelas,pleuropneumoniae, and atrophic rhinitis. No vaccineswere applied to piglets. Additionally for control of clinicalproblems tetracyclines and tiamulin were used.

Clinical symptoms clearly evoking PMWS includingwasting, anemia, respiratory disorders in weaners and alittle later in growers, were observed in November 2007.PMWS diagnosis was established following the criteria ofthe EU PCV2 consortium (www.pcvd.org). Laboratoryconfirmation consisted in microscopic analysis of lym-phoid tissue of the diseased pigs revealing lesionscharacteristic for PMWS and in situ hybridization showingabundant amount of PCV2 DNA within observed lesions.Simultaneously with clinical lesions of PMWS an increaseof mortality was observed. In an offspring of the 6following sow batches average total mortality, e.g. birthto slaughter rate, ranged from 23.07 to 37.24%. Thesevalues were significantly higher compared to averagemortality 15.27–19.15% observed in the offspring of 6 sowbatches preceding the occurrence of the syndrome.

Immunization with Circovac1 containing inactivatedPCV2 started in December 2007. Three different vaccina-tion protocols were used for three groups of sows and/ortheir progeny (Table 1). Six batches of sows werevaccinated twice, 3–4 weeks apart, before farrowingaccording to manufacturer’s recommendation (Sows only:‘‘S’’ group). Sows from the next six batches were notvaccinated but their piglets were injected at weaning, at 4weeks of age, with 0.5 ml of vaccine intramuscularly(Piglets only: ‘‘P’’). The following six batches of sows againwere vaccinated according to the producer’s recommen-dations but in addition their progeny were immunizedonce at 7 weeks of age with 0.5 ml of the vaccine (Sows andpiglets: ‘‘SP’’). Performance of an offspring from vaccinatedsows (group S), vaccinated piglets from non-vaccinatedsows (group P) and vaccinated piglets from vaccinatedsows (group SP) was analyzed from birth to slaughter andcompared to 6 batches of sows and progeny before PMWSand during PMWS outbreak (Table 1).

The following parameters were analyzed: mortality,weight at slaughter, ADWG and feed conversion ratio.Mortality was recorded daily for each group and recordswere summarized for separate barns every month. Resultswere considered to be unequivocal due to the strict all-inall-out management at all production stages. Weights atslaughter were obtained from a slaughterhouse recordsmatching pigs from every batch and the weights. Aparticular care was taken to avoid any overlap of thedifferent slaughtered batches. Body weight gain wascalculated using slaughter weight minus standardizedaverage birth weight. Average daily weight gain was

Vacc. sows only 636 6838 S

Vacc. piglets only 653 7187 P

Vacc. sows and piglets 608 6058 SP

Table 2

Slaughter weight, daily body weight gain, feed conversion ratio in experimental groups (mean� std) and average duration of fattening. Group S: pigs from

vaccinated sows; group P: vaccinated piglets from non-vaccinated sows; group SP: vaccinated piglets from vaccinated sows.

ADWG Feed conversion

ratio (kg/kg)

Total mortality (%) Slaughter weight (%)

Before PMWS outbreak 611.2� 9.09a 3.1� 0.08a 17.29� 1.48a 94.8� 1.56a

During PMWS outbreak 568.5� 7.18b 3.3� 0.06b 28.76� 4.89b 92.5� 1.16a

Group S 635.2� 6.24c 3.0� 0.10a 16.93� 0.63a 100.9� 1.35b

Group P 640.3� 3.50c 3.0� 0.05a 16.12� 0.90a 98.1� 0.54c

Group SP 656.0� 12.22d 3.0� 0.13a 15.35� 1.35a 98.6� 2.32c

a, b, c, d: significant difference (p< 0.05) in column.

Table 3

Mortality of pigs in different periods of life (mean %� std). Group S: pigs from vaccinated sows; group P: vaccinated piglets from non-vaccinated sows; group

SP: vaccinated piglets from vaccinated sows.

Month of age

1 2 3 4 5

Before PMWS outbreak 6.22� 0.49a 2.41� 0.80a 3.95� 0.40a 2.78� 0.36a 1.93� 0.46a

During PMWS outbreak 5.26� 0.31bc 5.98� 0.85b 8.36� 1.89b 5.19� 1.26b 2.97� 0.86b

Group S 4.77� 0.26bd 2.92� 0.30a 3.08� 0.37a 3.25� 0.52a 2.58� 0.58a

Group P 5.60� 0.39ac 3.18� 0.23a 3.21� 0.26a 2.11� 0.44c 2.21� 0.34a

Group SP 4.55� 0.53d 3.18� 0.26a 3.70� 0.98a 1.76� 0.34c 2.16� 0.44a

a, b, c, d: significant difference (p< 0.05) in column.

Z. Pejsak et al. / Comparative Immunology, Microbiology and Infectious Diseases 33 (2010) e1–e5 e3

calculated using the body weight gain as formerlydescribed divided by the duration of life (farrowing dayto slaughter day). Feed conversion rate was obtained bydividing for every batch total consumed feed per total kgbody weight per batch.

The results were statistically analysed using SYSTATVERSION 5.0 computer program (SYSTAT Inc.). First,verification of the homogeneity of variance by usingBarlett test was performed. Then, analysis of variancebetween groups by using ANOVA (if homogeneity ofvariance) or Kruskal–Wallis one-way test (if no homo-geneity of variance) was applied. Finally, comparison ofmean pair wise differences between groups using Tukeytest was performed. Significance of all statistical tests wasset at 0.05 (p< 0.05).

3. Results

The PMWS outbreak caused significant increase in totalmortality, decreased ADWG and increased feed conversion

Fig. 1. Mortality of pigs in di

ratio (Table 2). Average mortality in pigs from six batchesborn during the 2 months before the PMWS outbreak was17.29% and it increased to 28.75% in pigs born from mid-November to December 2007. During the outbreak themost severely affected age group were the 3-month-oldpigs (Table 3; Fig. 1).

Application of Circovac in sows brought significantimprovement in the performance of their offspring. Pigletsfrom the group S born from the end of January to the end ofFebruary performed as well as before the PMWS outbreak.Similarly well performed piglets from groups P and SP bornfrom beginning of March to beginning of May.

No difference could be observed between the groups S,P and SP in total mortality from birth to slaughter (Table 2).However, there were slight differences observed in effectsof different vaccination protocols for mortality of pigs indifferent age groups (Table 3, Fig. 1). A decrease of pre-weaning mortality was only recorded after vaccination ofsows (groups S and SP). In the second, third and fifthmonths of life no significant difference was observed in

fferent periods of life.

Z. Pejsak et al. / Comparative Immunology, Microbiology and Infectious Diseases 33 (2010) e1–e5e4

mortality between the 3 vaccination protocols. Mortalityin the fourth month of life was slightly lower in pigs whichwere vaccinated at 4 (group S) or 7 (group SP) weeks of agecompared to the group S,

During PMWS outbreak average duration of fatteningperiod increased from 155 to 163 days. ADWG droppedfrom 611.2 to 568.5 g and average weight at slaughterdecreased from 94.8 to 92.5 kg (Table 2) even thoughduration of fattening period was 8 days longer.

In other experimental groups, duration of fatteningperiod lasted 150 days in group SP, 153 days in group P and159 days in group S. In all of these groups ADWG increased,and slaughter weights were higher compared to non-treated groups. Interestingly, in group SP the ADWG wasfound significantly higher than before the outbreak(Table 2).

Feed conversion was significantly improved in all thevaccinated groups compared to the outbreak period.However, no difference was observed in feed conversionbetween the three vaccination groups (Table 2).

Additionally, in groups S, P and SP consumption ofantibiotics was reduced about 1/3 compared to the periodof PMWS outbreak.

4. Discussion

The principle of sow vaccination is to increase levels ofPCV2 specific immunity including neutralizing antibodiesand PCV2 specific functional immune cells that can betransferred to piglets [3]. Both these components ofimmune response help to protect piglets against PCV2massive exposure from the very beginning of their life, in aperiod when they are susceptible to immuno-compromis-sion. Further on, pigs are in consistent contact with PCV2,which is a ubiquitous resistant virus [1]. As piglets getolder and maternally derived antibodies slowly vanish,they mount their own PCV2 active immunity. On the otherhand, vaccination of piglets would directly provide activeimmunity to the piglets. Whether efficacy of vaccination inpiglets can eventually be affected by high levels ofmaternal antibodies is still controversial. The latest reportsindicated that maternal antibodies do not influencevaccine efficacy and seem to indicate that from 3 to 4weeks of age onward, there would not be a significantdecrease in efficacy of PCV2 vaccination [10]. However,none of the experiments was performed on pigs fromvaccinated sows, which are expected to have higher levelsof antibodies than those from non-vaccinated, seropositivesows. In this trial, a delayed pig vaccination time wasselected to minimize the potential negative impact ofmaternal antibodies on vaccination efficacy in pigs.

In this work we compared efficacy of the three differentvaccination protocols in a herd where an acute PMWSoutbreak started a few weeks earlier and where the mostacute symptoms were observed in 3-month-old pigs. Allthree protocols, namely vaccination of sows, piglets orsows and piglets with Circovac proved to be efficacious incontrolling of PMWS. The vaccine was very well toleratedby piglets and by sows. Transient depression and anorexiawas observed in less than 1% of vaccinated piglets. No localadverse reaction was noted.

All production parameters significantly improved aftervaccination and obtained values were as good as before theoutbreak, or even better as in the case of ADWG. The latterparameter was significantly higher in the group SP wherepigs from vaccinated sows were vaccinated at 7th weeks ofage. On the other hand, vaccination of sows significantlydecreased pre-weaning mortality in groups S and SP. It hasbeen well established that in pigs further growth is relatedto weight and health status at weaning [15]. This confirmsprevious results showing that sow PCV2 vaccination wasleading to an increase of pre-weaning ADWG [6]. Inter-estingly, vaccination of sows coincided also with increaseof efficiency of insemination rate of about 7% (not shown).As no laboratory analysis was made, it can be onlyspeculated that this effect was seen due to control of sub-clinical infections in sows. Vaccination of piglets at 4 weeksof life or piglets from vaccinated sows at 7th weeks of ageresulted in the lowest mortality during the fourth month oflife but the difference between the vaccinated groups wasnot significant later in life. However, profiles of mortalityrates over time look very similar among the vaccinationprograms.

The results of this study indicate that Circovac iseffective in improving production parameters whenapplied in sows, piglets, or sows and piglets. Pigs fromthe batches vaccinated according to different protocols hadmarkedly reduced mortality compared to the batches fromthe PMWS outbreak. Also, there was a significantimprovement in ADWG ranging from 66.7 to 87.5 g.Consequently, pigs gained slaughter weight in shorterfattening period. Moreover, ADWG improved by 24–45 galso if compared to the period preceding the outbreak,what suggests that the impact of sub-clinical PCV2infections in pigs may be underestimated. These resultsare in agreement with earlier observations with othervaccines [4,16].

The highest ADWG in group SP may have severalexplanations. When only sows are vaccinated, some pigsmay not get the sufficient amount of colostrum and whenpiglets only are vaccinated, in acute outbreak, with a highvirus pressure, some of them may be immuno-compro-mised to such a degree that this will impair the activeimmunization. When both are vaccinated, and providedthat there is no interference between passive immunityand active immunization by vaccination, it can be expectedthat growth performance is optimized. A second explana-tion may also sit in the fact that after 6 batches ofvaccinated sows and 6 batches of vaccinated piglets, PCV2pressure may have decreased and become less detrimentalto the immune balance of the herd and the growthperformances.

Previous studies invariably shown that PCV2 vaccineswere very effective and immunization resulted in con-siderable cost savings [5,6,16]. In the present trial benefitsrelated to lower feed consumption in vaccinated animalswere approximately 3-times higher compared to incurredcosts. Furthermore, this calculation does not include othercost-beneficial factors, such as costs of labor connectedwith longer fattening period and lower post-weaningmortality. The latter parameter gained the lowest value inSP group, what makes this immunization program

Z. Pejsak et al. / Comparative Immunology, Microbiology and Infectious Diseases 33 (2010) e1–e5 e5

especially economically attractive. However, before imple-menting such solution in farm, benefits should be analyzedcase by case versus vaccine and labor costs.

5. Conclusion

In this farm acutely affected with PMWS, the efficacy ofPCV2 vaccination was confirmed. The three vaccinationprograms gave good improvement in terms of mortalityrates, growth, feed efficiency number of antibiotic treat-ments. In this trial, the better growth was obtained usingsow and piglet vaccination. Interestingly, pre-weaningmortality when sows were vaccinated as well as ADWG forall vaccination programs turned out to be even signifi-cantly better than before PMWS outbreak, suggesting thata sub-clinical impact of PCV2 may be underestimated.

References

[1] Allan GM, Ellis JA. Porcine circoviruses: a review. J Vet Diagn Invest2000;(12):3–14.

[2] Calsamiglia M, Fraile L, Espinal A, Cuxart A, Seminati C, Martin M,et al. Sow porcine circovirus type 2 (PCV2) status effect on littermortality in postweaning multisystemic wasting syndrome(PMWS). Res Vet Sci 2007;(82):299–304.

[3] Goubier A, Chapat L, Toma S, Piras F, Joisel F, Maurin-Bernaud L,Charreyre C, Andreoni C, Juillard V. Transfer of maternal immunityfrom sows vaccinated against PCV2 with CIRCOVAC1 to their piglets.In: Proceedings of the 20th IPVS Durban, South Africa; 2008. p. 16.

[4] Henry S. PCV2 studies: research from the K-State PCV2 Team. In:Proceedings of the 39th Annual Meeting of AASV; 2008. p. 463–7.

[5] Joisel F, Brune A, Schade A, Longo S, Charreyre C. Results of thevaccination against PCV2 diseases with Circovac1 in 233 Germansow herds: decrease in mortality. In: Proceedings of the 5th Inter-national Symposium on Emerging and Re-emerging Pig DiseasesKrakow; 2007.p. 126.

[6] Joisel F, Brune A, Schade A, Longo S, Charreyre C. Results of thevaccination against PCV2 diseases with Circovac1 in 233 Germansow herds: improvement of pig growth and decrease in antibiotictreatments. In: Proceedings of the 5th Emerging and Re-emergingPig Diseases Krakow; 2008.p. 127.

[7] McIntosh KA, Harding JC, Parker S, Krakowka S, Allan G, Ellis JA.Quantitative polymerase chain reaction for Porcine circovirus-2 inswine feces in a Porcine circovirus disease-affected commercialherd and a nonaffected commercial herd. Can Vet J 2008;(49):1189–94.

[8] Misinzo G, Delputte PL, Lefebvre DJ, Nauwynck HJ. Porcine circovirus2 infection of epithelial cells is clathrin-, caveolae- and dynamin-independent, actin and Rho-GTPase-mediated, and enhanced bycholesterol depletion. Virus Res 2009;(139):1–9.

[9] Opriessnig T, Meng XJ, Halbur PG. Porcine Circovirus Type 2 asso-ciated disease: update on current terminology, clinical manifesta-tions, pathogenesis, diagnosis, and intervention strategies. J VetDiagn Invest 2007;(19):591–615.

[10] Opriessnig T, Patterson AR, Elsener J, Meng XJ, Halbur PG. Influenceof maternal antibodies on efficacy of porcine circovirus type 2(PCV2) vaccination to protect pigs from experimental infection withPCV2. Clin Vaccine Immunol 2008;(15):397–401.

[11] Rose N, Larour G, Le Diguerher G, Eveno E, Jolly JP, Blanchard P, et al.Risk factors for porcine post-weaning multisystemic wasting syn-drome (PMWS) in 149 French farrow-to-finish herds. Prev Vet Med2003;(61):209–25.

[12] Tomas A, Fernandes LT, Valero O, Segales J. A meta-analysis onexperimental infections with porcine circovirus type 2 (PCV2).Vet Microbiol 2008.

[13] Vincent IE, Carrasco CP, Guzylack-Piriou L, Herrmann B, McNeilly F,Allan GM, et al. Subset-dependent modulation of dendritic cellactivity by circovirus type 2. Immunology 2005;(115):388–98.

[14] Vincent IE, Carrasco CP, Herrmann B, Meehan BM, Allan GM, Sum-merfield A, et al. Dendritic cells harbor infectious porcine circovirustype 2 in the absence of apparent cell modulation or replication ofthe virus. J Virol 2003;(77):13288–300.

[15] Wolter BF, Ellis M. The effects of weaning weight and rate of growthimmediately after weaning on subsequent pig growth performanceand carcass characteristics. Can J Anim Sci 2001;(81):363–9.

[16] Young M, Cunningham G, Sanford E. Performance of Ingelvac Circo-flex1 vaccinated pigs in a subclinical PCVAD herd. In: Proceedings ofthe 20th Congress IPVS Durban; 2008.p. 25.