Generation And Characteristics Of Monoclonal Antibodies Against Infectious Bronchitis Virus

Infectious bronchitis (IB), also called avain infectious brochitis, is a common acute highlycontagious viral infectious disease caused by coronavirus infectious bronchitis virus (IBV) and ofteninduce serious economic losses in poultry industry. While infected with IBV, the lesions mainly occur inrespiratory, digestive and urogenital system. Since Schalk and Hawn first report IB in1931, IBV hasconstantly developed and more than100kinds of serotypes has emerged. Due to the poorcross-protection in different serotypes, the diagnosis and prevention of IB become difficult. Researchabout IBV monoclonal antibody (MAb) not only can help to understand its antigenic structure, but alsoto design rational and scientific vaccine or diagnosis reagents, so it has vital significance for preventionand diagnosis of IB.BALB/c mice were immunized with IBV ck/CH/LDL/091022, by traditional cell fusion techniqueand limited dilution method, two hybridoma cell lines that secreted MAbs against IBV N protein and S1protein were obtained and designated as2F2and3G9respectively. Subtype identification showed thatMAb2F2and MAb3G9both belonged to IgG1and their light chains were к chain. Western blot andELISA analysis indicate that both of the MAbs can react with IBV ck/CH/LDL/091022and otherserotype IBV stains. The specific band of MAb2F2with IBV strains was sized at45kDa, and the MAb3G9was90kDa. By preparing recombinant N protein and S1protein of IBV and reacting with MAb2F2and MAb3G9respectively, the results showed that MAb2F2was against IBV N protein and MAb3G9against IBV S1protein.To precisely identify the epitope recognized by MAb2F2, study conservation or viriation featuresof the epitope and help to provide evidence for developing diognosis methods and reagents,23peptidescovered IBV N protein and partially overlapped were expressed with GST tag by prokaryotic expression.The result of Western blot and ELISA indicated that the linear motif397INWGDSAL404was the minimalepitope. Western blot analysis with different IBV strains and conservative analysis of the correspondingsequences showed that the epitope sequence was conserved among most IBV stains.As IBV S1subunit is usually related with neutrlizing activity, to research the neutralizing activityof MAb3G9, we conducted neutralization test by fixing sreum and diluting virus, the neutralizationindex (NI) is117, the result showed that neutralizing activity of MAb3G9was good. It can be used ascandidate antibody to develop diagnosis and prevention reagents of IB.