Differential diagnosis of fish pathogenic rhabdoviruses by reverse transcriptase-dependent polymerase chain reaction

Reverse transcriptase-dependent polymerase chain reaction (RT-PCR) was applied to the detection and differentiation of viral hemorrhagic septicemia virus (VHSV) and infectious hematopoietic necrosis virus (IHNV) using primer pairs designed for the amplification of glycoprotein G-specific gene fragments of the two viruses. The products of 443 bp (VHS) and 548 bp (IHN), respectively, were amplified from the total RNA extracts of RTG-2 cells infected with a total of 9 different strains of either VHS virus or IHN virus. Restriction analysis using FokI, and DNA sequencing of the PCR products demonstrated specificity of the amplification. The RT-PCR amplification of VHSV or IHNV G-genes was found to be a simple, highly specific and sensitive method allowing differential diagnosis of VHS and IHN within 8 h.