Antigenic relatedness of vaccine virus strain CDC-RG 30 to strains of AI virus A/H5N1 clade 1.1, 2.3.2.1c

Abstract

Antigenic differences between vaccine virus strain CDC-RG30 and the strains of AI virus A/H5N1 clade 1.1, 2.3.2.1c, 2.3.4 and vaccine strain NIBRG-14 were studied. The studied result indicated that HI titre reached a high level when antigen used for HI test was the homogeneous strains (or clades) and a lower value of HI was observed when using antigen of the heterogeneousstrains.By using cross HI test and basing on R value, the tested result demonstrated that there was no antigenic difference between vaccine strain CDC-RG30 and AI virus clade 2.3.2.1c, with R value was more than 70%. However, the difference of antigen between CDC-RG30 strain with others, such as AI virus clade 1.1, 2.3.4 and vaccine strain NIBRG-14 was observed in this study.Interestingly, although the antigenic difference of CDC-RG 30 strains to others was found, the chickens and ducks that were vaccinated with vaccine producing from CDC-RG 30 strain could be protected against the high pathogenic AI virus A/H5N1 clade 1.1, 2.3.2.1c provided by challenging experiment