Three major isolates of BmDNV are identified viz. BmDNV-1 (Ina isolate), BmDNV-2 (Saku isolate and Yamanashi isolate), and DNV-Z (Zhenjiang isolate), classified into type I [DNV-1] and type II [DNV-2] based on their genomic characteristics ( Tijssen and Bergoin, 1995 and Wang et al., 2007).