A new variant of rabbit hemorrhagic disease virus G2-like strain isolated in China

To investigate the genetic variability and evolution of rabbit hemorrhagic disease virus (RHDV) strains in China, VP60 gene sequences of eight new isolates collected from farms with RHD occurrences in China between 2009 and 2014 were analyzed, and compared with the reference sequence of the vaccine strain WF/China/2007. We conducted a comprehensive analysis of the Chinese RHDV strains, including hemagglutination tests, western blot and immunosassays of capsid proteins, and phylogenetic analysis, and identified a new distinct antigenic variant. Specifically, strain HB/2014 collected in North China was identified as a non-hemagglutinating strain, and belongs to the original RHDV (G1-G5) group. The other seven isolates were classified in genogroup G6 (RHDVa), which was widely distributed across China before 2014, and was thought to replace the earlier groups. Antigenic characterization of the VP60 genes revealed a large degree of nucleotide sequence divergence between HB/2014 and the other Chinese strains. However, the current vaccine showed complete cross-protection against HB/2014 challenge in inoculated rabbits. Collectively, these data provide new tools and insight for further understanding the molecular evolution of RHDV in China.