Antigenic characterization of hemagglutinin-neuraminidase (HN) protein of avian paramyxoviruses by specific antisera to isolated HN subunits.

Specific antisera for the isolated HN proteins of eight reference strains of avian paramyxoviruses could be prepared in guinea pigs by intraperitoneal injection of guinea pig red blood cells (GRBC) coated with purified HN proteins. In the hemagglutination inhibition (HI) tests, all reference strains reacted strongly with each homologous antiserum to the isolated HN showing that a low level of cross-reactivity among the reference strains was greatly diminished by using specific antisera. Immuno-double-diffusion (IDD) tests showed that all antisera except those to turkey/Wisconsin/68 and duck/Hong Kong/D3/75 gave single well-defined lines only with the homologous viruses. The remaining two antisera developed a single definite precipitin line together with weak lines with homologous virus. Two isolates in Japan were clearly identified in HI and IDD tests with specific antisera to the HN subunits of the reference strains suggesting that the antisera were useful for identification of avian paramyxovirus isolates. Two isolates in Japan, H-70 from a munia-bird and Y-7 from a duck were found to have HN proteins related closely to those of finch/N. Ireland/Bangor/73 and duck/Hong Kong/199/77, respectively.