A ribonuclease protection assay can distinguish spring viremia of carp virus from pike fry rhabdovirus

Thirteen rhabdovirus isolates from 10 teleost fish species as well as reference strains of spring viraemia of carp virus (SVCV) and pike fry rhabdovirus (PFRV) cross-reacted in an indirect immunofluorescence assay and were thus indistinguishable by this method. A ribonuclease protection assay (RPA) using a super(32)P-labeled RNA probe made from a cloned copy of the full length SVCV glycoprotein (G) gene was able to discriminate clearly between the type strains of SVCV and PFRV and among the 13 rhabdovirus isolates. Results for the RPA were generally in agreement with standard serum neutralisation assays; however, the RPA was also able to detect genomic differences between isolates of SVCV. These results have implications for fish disease control programs for SVCV.