Molecular cloning of the mRNA coding for the G protein of the viral haemorrhagic septicaemia (VHS) of salmonids

Viral haemorrhagic septicaemia virus (VHSV), a rhabdovirus, is a major threat for continental European trout fish farming. The development of a recombinant subunit vaccine could solve that problem. The neutralizing epitopes are located on the glycoprotein or G protein, the surface antigen. The G protein has a molecular weight of 65 kDa, reduced to 55 kDa by deglycosylation. cDNA was synthetized from mRNA of VHS virus infected cells, and cloned in E. coli. The viral cDNA was recognized by positive hybridization with a labelled probe made from infected cell RNA, and negative hybridization with labelled cDNA made from cellular RNA. The Northern blot hybridization with different clones on VHS infected cell RNA revealed two VHS mRNA whose lengths, 2.0 and 1.5 kb, were compatible with the mRNA length for G and N proteins respectively. This mRNA must contain about 400 bp of untranslated sequence.