Expression of Capsid Proteins from Infectious Pancreatic Necrosis Virus (IPNV) in the Marine Bacterium Vibrio Anguillarum

Abstract

V. anguillarum is a marine fish pathogen with serotype O1 strains comprising the major disease-causing serotype (Crosa et al., 1980). Two components of a high-affinity iron uptake system encoded by the virulence plasmid pJM1 are the secreted siderophore, anguibactin, and the outer membrane protein receptor for iron-siderophore complexes, OM2. Because formalin-inactivated serotype O1 strains are used commercially as vaccines for the prevention of vibriosis in salmonids, we explored the use of V. anguillarum as an expression host for protective epitopes of the major capsid protein VP2 from infectious pancreatic necrosis virus (IPNV). IPNV causes primarily a disease of salmonid fry, but survivors become life-long carriers and serve as reservoirs of future infection (Dobos & Roberts, 1983). Segment A of the bisegmented dsRNA IPNV genome is 2.9 kb and is translated from a single open reading frame into a polyprotein which is subsequently cleaved into three proteins, VP2, NS and VP3 (Huang et al., 1986). The major capsid protein of the virus, VP2 (59 kDa), contains most of the neutralization epitopes (Caswell-Reno et al., 1986). NS is the non-structural polyprotein protease and VP3 is a minor structural protein. We show here that IPNV cDNA in a translational fusion with V. anguillarum DNA results in production of IPNV and OM2 hybrid proteins expressed in V. anguillarum.