Serological Properties of Neutralizing Antibodies Induced by Vaccination of Rainbow Trout with Distinct Strains of Infectious Pancreatic Necrosis Virus

Abstract

Adult rainbow trout Oncorhynchus mykiss were immunized with formalin-inactivated, concentrated infectious pancreatic necrosis virus (IPNV). Although the immune response was variable among fish inoculated with a given virus type, sera were obtained that contained high titers of antibodies against known representatives of each of the three major serotypes and several unclassified field isolates of IPNV. Preparations of semipurified macroglobulins from the rainbow trout were subsequently used for comparative cross-neutralization testing of viruses. Cross-reactions were generally low between serotypes; however, diversity and heterogeneity existed among viral isolates from North American hatcheries (e.g., within serotype 1). For example, the Jasper subtype was clearly serologically distinguishable from other western Canadian isolates and from typical eastern Canadian isolates, which were similar to U.S. isolate VR 299. Specific salmonid immunoglobulin is suggested as a possible supplemental reagent, together with mammalian polyclonal and monoclonal antibody, for determining the epidemiology of IPNV in North America.