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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Endemic Poultry Viral Diseases Research » Research » Publications at this Location » Publication #309508
Title: S2 expressed from recombinant virus confers broad protection against IBV

Author
item TORO, HAROLDO - Auburn University
item Yu, Qingzhong
item VAN SANTEN, VICKY - Auburn University
item GHETAS, ALY - Auburn University

Submitted to: International Symposium on Avian Corona and Pneumoviruses and Complicating Pathogens
Publication Type: Proceedings
Publication Acceptance Date: 7/18/2014
Publication Date: 11/1/2014
Citation: Toro, H., Yu, Q., Van Santen, V., Ghetas, A. 2014. S2 expressed from recombinant virus confers broad protection against IBV. In: 8th International Symposium on Avian Corona- and Pneumoviruses and Complicating Pathogens. 2nd Annual Meeting of the COST Action FA1207, June 17-20, 2014, Rauischholzhausen, Germany. p. 348-356.

Interpretive Summary: Infectious bronchitis (IB), caused by infectious bronchitis virus (IBV) infection, is one of the most prevalent avian diseases in the world’s poultry industry. Effective control of IBV is particularly difficult due to genotype/phenotype diversity and continuing evolution of the virus. Previously we demonstrated that chickens primed with a recombinant Newcastle disease virus LaSota virus (rLS) expressing the IBV S2 gene (rLS/IBV.S2) and boosted with an attenuated IBV Massachusetts (Mass)-type vaccine were protected against heterologous IBV Arkansas (Ark)-type virulent challenge. In the present study, we evaluated protection conferred by single vaccination with rLS/IBV.S2 or simultaneous vaccination with a combination of rLS/IBV.S2 vaccine and attenuated Mass-type IBV vaccine. The results showed that the single and simultaneous vaccination did not induce the same level of protection as the primer and boost vaccine scheme. To provide a better cross-protection against different serotype IBV, we generated a rLS/IBV expressing an artificially designed consensus S2 gene representing North American IBV serotypes. This customized rL/IBV.S2 recombinant conferred more effective protection against Ark challenge when used in a prime-boost regime with attenuated Mass virus than priming and boosting exclusively with Mass vaccine. The promising results warrant further investigation of this recombinant virus on protection against other serotype IBV challenges.

Technical Abstract: We previously demonstrated that chickens primed with a recombinant LaSota virus (rLS) expressing the IBV S2 gene (rLS/IBV.S2) and boosted with an attenuated IBV Massachusetts (Mass)-type vaccine were protected against heterologous IBV Arkansas (Ark)-type virulent challenge. In the current study, we determined that single vaccination with rLS/IBV.S2 elicits a level of protection considerably less than the level of protection achieved by the prime and boost vaccination regime. This result was expected as the fundamental premise of this technology relies on the secondary immune response to the S2 protein. Furthermore, we evaluated protection conferred by simultaneous vaccination with a combination of rLS/IBV.S2 vaccine and attenuated Mass-type IBV vaccine. Because the protection resulting from vaccination with rLS/IBV.S2+Mass did not differ significantly from that resulting from vaccination with empty vector (rLS/E)+Mass, the level of protection observed (when compared to controls vaccinated with rLS/E alone) is attributable only to the effect of the Mass vaccine. The absence of benefit achieved by combined vaccination was expected because of the missing booster effect to the S2 and by reduced replication of the rLS likely resulting from competition with IBV for cell receptors. Indeed, comparison of Newcastle disease virus (NDV) antibodies measured 20 days after rLS/E-only versus rLS/E+Mass combined vaccination showed significantly less antibodies in the combined vaccinated chickens. Finally, we developed and initially tested an rLS expressing an artificially designed consensus S2 gene representing North American IBV serotypes. The customized S2 insert did not alter the essential biological properties of the NDV vector. The artificially designed S2 gene insert conferred more effective protection against Ark challenge when used in a prime-boost regime with attenuated Mass virus than priming and boosting exclusively with Mass vaccine.