ucero et al Virol Antivir Res 2 DI 222- Journal of ... and Ability to Confer Protection Against Infectious Bursal Disease. J Virol Antivir Res 5:4. • Page 2 of 7 • doi: 10.4172/2324-8955.1000161

a SciTechnol journal Research Article Lucero et al., J Virol Antivir Res 2016, 5:4 DOI: 10.4172/2324-8955.1000161 All articles published in Journal of Virology & Antiviral Research are the property of SciTechnol, and is protected by copyright laws. Copyright © 2016, SciTechnol, All Rights Reserved. Journal of Virology & Antiviral Research International Publisher of Science, Technology and Medicine Effect of Different Routes of Inoculation on Plant-Derived VP2 Immunogenicity and Ability to Confer Protection Against Infectious Bursal Disease María Soledad Lucero 1 , Evangelina Gomez 1,2 , Matías Richetta 1,3 , Silvina Chimeno Zoth 1,2 ,Juan Manuel Carballeda 1,2 , María José Gravisaco 1 , Fernando Delgado 4 and Analía Berinstein 1,2 Abstract Infectious Bursal Disease Virus (IBDV) is the etiological agent of an immunosuppressive and highly contagious disease that affects young birds causing important economic losses in the poultry industry. The structural protein VP2 has been used for the development of subunit vaccines in a variety of heterologous platforms. We have previously demonstrated that plant-derived VP2 (pVP2) is able to elicit a neutralizing antibody response in chickens when administered intramuscularly (i.m.) in a prime/boost scheme. However, administration via injection is impractical and carries the risk of needle stick injury or pain. Mucosal vaccination is noninvasive and has several advantages over traditional systemic vaccines. Taking this into account and the fact that natural infections with IBDV occur by the oral route, we decided to investigate whether pVP2 was also immunogenic when given intranasally (i.n.) or orally to chickens. In addition, we evaluated if intramuscular vaccination with VP2 plant extract in a more welfare- friendly scheme with less injections and without adjuvant was able to elicit a protective immune response against IBDV as previously seen. We determined that animals inoculated i.m., but not i.n., with the experimental vaccine developed high titres of specific antibodies, with virus neutralizing activity. Also, bursae of animals vaccinated i.m. with pVP2 presented few infiltrating T cells, low viral charge and normal morphology. However, chickens that received the immunogen via nasal or oral route were not protected after challenge. Considering the disadvantages of conventional live-attenuated and inactivated vaccines, a plant-based subunit vaccine represents a viable alternative in the veterinary field. Once again pVP2 has proven to be immunogenic when parentally inoculated. However, further investigations need to be done in order to find an alternative route of administration which is more practical than the intramuscular injection and capable of eliciting a mucosal immune response Keywords Infectious Bursal Disease; VP2; Plant based vaccine *Corresponding author: Analía Berinstein, Veterinary Research Center and Agricultural Sciences, National Agricultural Technology Institute, Cc 25 B1712WAA, Castelar, Buenos Aires, Argentina, Tel: 54 11 4621 1447 ext 147; E-mail: [email protected] Received: August 08, 2016 Accepted: September 01, 2016 Published: September 09, 2016 Introduction Infectious Bursal Disease is an acute, highly contagious, immunosuppressive disease that affects young birds causing important economic losses in the poultry industry worldwide. Its etiological agent is the Infectious Bursal Disease Virus (IBDV), a non-enveloped icosahedral bisegmented double-stranded RNA virus, member of the Birnaviridae Family [1]. IBDV infects and destroys IgMbearing B-lymphocytes in the bursa of Fabricius (BF), which results in immunosuppression [2,3] and T cells infiltration into this organ [4]. Currently, vaccination with inactivated and live-attenuated vaccines induces immunity in the flock against virulent viruses. However, conventional vaccines have a number of disadvantages because of their viral nature. For instance, live-attenuated vaccines can revert to virulence by recombination of RNA segments [5], they usually produce a temporary state of immunosuppression in young chickens, and they can be inefficient in protecting birds from very virulent and variant IBDV strains [6,7]. Moreover, inactivated vaccines are costly and lack efficient immunogenicity unless they are adjuvated and administered in multiple inoculations, or delivered as a booster aﬅer priming with a replicating antigen. us, there is a genuine need to replace conventional virus-based vaccines by new ones with higher efficacy and fewer side-effects. e structural protein VP2, which contains the major neutralizing epitopes, has been used for the development of subunit vaccines in a variety of heterologous systems such as recombinant fowlpoxvirus [8], herpesvirus [9-11], adenovirus [12,13], baculovirus [14,15], Escherichia coli [16], Pichia pastoris [17] and plant virus [18]. In addition, DNA vaccines have been obtained [19, 20] and VP2 production and immunogenicity have been reported in transgenic Arabidopsis thaliana [21] and rice [22]. Since the past two decades plants have been considered a promising system to produce subunit vaccines given that they offer significant advantages over conventional expression systems, such as time and cost efficiency, lower risk of contamination from animal pathogens and nearly-unlimited scalability [23]. Furthermore, it is well documented that antigens expressed in planta are capable of inducing protective response when administered by oral or parenteral routes. For these reasons, the technology to produce recombinant vaccines in plant cells has evolved from modest proofs of concept to viable technologies adopted by some companies [24]. In a previous study, we investigated the expression, immunogenicity and protective efficacy of a plant-based VP2 (pVP2) vaccine against IBDV [25]. We determined that agroinfiltration of N.benthamiana leaves allowed the production of VP2 and that chickens intramuscularly immunized in a 3 doses scheme with adjuvated concentrated plant extract developed a specific humoral response with viral neutralizing capacity. We also demonstrated that pVP2 had the ability to prevent T-cell infiltration into the bursa as a parameter of protection against an infectious virus. However, administration via injection is impractical and carries the risk of needle stick injury or pain. Mucosal vaccination is non-invasive and does not involve the use of needles. Moreover, mucosal administration of vaccines is relatively easy and does not require specialized personnel.

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ucero et al Virol Antivir Res 2 DI 222- Journal of ... and Ability to Confer Protection Against Infectious Bursal Disease. J Virol Antivir Res 5:4. • Page 2 of 7 • doi: 10.4172/2324-8955.1000161