Molecular biology of the viral haemorrhagic disease virus of rabbits.

Viral haemorrhagic disease virus (VHDV) of rabbits is a small, nonenveloped DNA virus which contains a linear, single-stranded genome approximately 7,000 bases in length. The virions are icosahedral in symmetry, consisting of 180 subunits with pentamer-hexamer clustering. The capsid is composed of four structural polypeptides: VP1:60-61 kDa, VP2:54.7 kDa, VP3:52 kDa, and VP4:26-28 kDa. VP1 is a major structural polypeptide which constitutes approximately 54.7% of the total viral proteins. There are extensive antigenic relationships among the polypeptides. Haemagglutination activity is associated with the intact virions. The genome of the VHDV isolate strain (VHDV-NJ) is partially cloned, and 4.6 kb DNA fragment of restriction mapping has been determined, showing that there are few common restriction sites compared with the restriction site mapping of the parvoviruses. There are five viral-specific mRNA species, each coding for one of the five polypeptides identified by in vitro translation. The cDNA library from viral mRNA has been established. Southern blot hybridisation shows that, to some extent, H-I virus, minute virus of mice, porcine parvovirus and goose parvovirus share homology with VHDV. However, to clarify VHDV taxonomy, further efforts must be directed towards VHDV genome analysis.