Protection and antibody response induced by intramuscular DNA vaccine encoding for viral haemorrhagic septicaemia virus (VHSV) G glycoprotein in turbot (Scophthalmus maximus)

Turbot (Scophthalmus maximus) is a high-value farmed marine flatfish with growing demand and production levels in Europe susceptible to turbot-specific viral haemorrhagic septicaemia virus (VHSV) strains. To evaluate the possibility of controlling the outbreaks of this infectious disease by means of DNA vaccination, the gpG of a VHSV isolated from farmed turbot (VHSV860) was cloned into an expression plasmid containing the human cytomegalovirus (CMV) promoter (pMCV1.4-G860). In our experimental conditions, DNA immunised turbots were more than 85% protected against VHSV860 lethal challenge and showed both VHSV-gpG specific and neutralizing antibodies. To our knowledge this is the first report showing the efficacy of turbot genetic immunisation against a VHSV. Work is in progress to determine the contribution of innate and adaptive immunity to the protective response elicited by the immunization.

► Turbots were vaccinated with a plasmid encoding the cDNA sequence of the gpG of a VHSV isolated from turbot. ► DNA vaccinated turbots were protected against challenge with a pathogenic VHSV strain isolated from turbot. ► DNA vaccinated turbots showed both VHSV-gpG specific and neutralizing antibodies. ► This is the first report showing the efficacy of a turbot DNA vaccine against a VHSV.