Antigenic variation among Nigerian strains of equine H3 influenza viruses.

Antigenic variation among three recent isolations of equine-2 H3N8 influenza viruses from Ibadan, Nigeria is reported.Antigenic analysis with panels of monoclonal antibodies (mAbs) and polyclonal antisera indicated that the three viruses were antigenically divergent, although they were all H3N8 subtype related to other equine 2-viruses isolated between 1963 and 1987.Results of virus protein synthesis investigated by pulse-chase experiments showed heterogeneity among the proteins of the ribonucleoprotein complex and the haemagglutinin glycoproteins, which were not cleaved in tissue culture.The results of this study indicate that equine H3 HAs have evolved by a process of evolutionary divergence and mutational changes, as confirmed by genetic analysis in another study.The results also showed that antigenic variation occurs among equine H3 influenza viruses and that H3 viruses with antigenically different HA molecules could co-circulate in equine populations.