TYPE-SPECIFIC ANTIGENICITY OF AVIAN REOVIRUSES

The type-specificity of the neutralizing activity in chicken antiserum to avian reoviruses was affected by the method of antiserum productio n. The neutralizing activity produced in response to virus infection h ad higher type-specificity than that produced by immunization with ina ctivated virus emulsified in adjuvant. By using reassortant viruses th e induction of type-specific neutralizing activity was shown to be ass ociated with the sigma C (sigma C) virion protein. Antigenic classific ation of virus strains based on immunoprecipitation of the sigma C pro tein by chicken antiserum was attempted and the results were similar t o those obtained by reciprocal serum neutralization tests. One-way imm unoprecipitation of the sigma C protein by antisera to some heterologo us viruses, similar to that reported in reciprocal neutralization test s, made it difficult to assign individual viruses to serogroups and sh owed that the type-specificity of the sigma C protein was not absolute . The neutralization activity of monoclonal antibodies to the sigma C protein of the RAMI strain of avian reovirus suggested there were sepa rate type- and group-specific antigenic domains on the sigma C protein , and that the group-specific domains may be associated with the induc tion of antibody against heterologous viruses.