Epidemiological Survey of Grass Carp (Ctenopharyngodon idella) Reovirus in South China, and Genetic Variations of VP6 gene

Abstract

To study the molecular biology characteristics, phylogenetic relationship, and status quo of grass carp reovirus (GCRV) prevalent isolates, we conducted an epidemiological survey in South China from 2012 to 2016. We sampled 126 fish collected from five provinces. Eight strains of GCRV were isolated and examined in order to understand their genetic characteristics and evolution regularity. The results showed three genotypes of GCRV, of which. Genotype Ⅱ was found to be the prevalent strain in South China. SDS-PAGE electrophoresis further suggested that all viruses possess 11 segments of dsRNA, which have typical characteristics of GCRV. Based on amino acid sequence phylogenetic tree of VP6 gene, all eight isolates belonged to genotype Ⅱ and had significant variations compared to genotype Ⅰ. Analysis of amino acid sequence showed that these two genotypes of GCRV had no immunological cross-reactions. These results indicated that genotype Ⅱ GCRV is an extensive pandemic, and revealed new genetic diversity in China.