Monoclonal Antibodies to Recombinant Protein VP7 of Bluetongue Virus
Blutang or catarrhal fever of sheep is a viral transmissible infection of ruminants, which is one of the economically significant arbovirus infections of animals. Viral VP7 is a group-specific core protein of the virus, conservative for all its known serotypes, and therefore represents the most suitable target for the development of diagnostic tests. For the development of an immunochemical method for detecting viral infection, a panel of monoclonal high-affinity antibodies to VP7 was obtained. As immunogens, the N-terminal VP7 fragment expressed in E coli and inactivated virus particles were used. The obtained monoclonal antibodies are applicable to detect the virus in infected cells. As a species-specific antigen, a recombinant protein TrxA–VP7_а was created, which contained spatial epitopes similar to those in the native viral antigen. Using it, promising antibodies were selected for the diagnostics of BTV by competitive enzyme immunoassay (EIA) that enabled identification of specific antibodies in sera of infected animals. By competitive solid-phase EIA it was shown that antibodies interacting with TrxA–VP7_а the most efficiently (Bt14, Bt15, Bt18, Bt26, Bt33, Bt34 and Bt35) had close or overlapping epitopes. Interaction of virtually all produced antibodies with the antigen was inhibited by specific reference sera against 24 serotypes of BTV. Bt14 monoclonal antibody exhibited the maximum ability to block VP7 interaction with specific sera against 24 bluetongue serotypes. Thus, the obtained panel of monoclonal antibodies to VP7 of bluetongue virus can be used to detect viral infection, as well as as a component of sets for serological diagnosis of the disease.