Development of an improved RT-PCR for specific detection of spring viraemia of carp virus

Spring viraemia of carp (SVC) is a rhabdovirus infection, which has a significant economic impact in pond cultures of carp in Europe and western Independent States of the former Soviet Union. The causative agent of SVC, spring viraemia of carp virus (SVCV), has been divided into four subgroups, Ia, Ib, Ic and Id, on the basis of glycoprotein (G) protein gene sequences. In this study, a new primer set was designed from a G gene sequence of SVCV to identify the four subtypes of SVCV by reverse transcription polymerase chain reaction (RT-PCR). The specific PCR products of 369 bp were amplified from 15 SVCV isolates of all four subtypes. However, pike fry rhabdovirus (PFRV), which is antigenically related to SVCV, and other viruses antigenically related to SVCV and PFRV were not amplified. The four subtypes of SVCV were specifically amplified by the RT-PCR. Furthermore, the detection limit of the RT-PCR was 7.1 × 10(2) copies/reaction, and it was not influenced by the addition of RNA extracted from fish tissues. The RT-PCR will be applied not only to RNA extracted from viral suspensions, but also from fish tissue. It will contribute to rapid identification of SVCV in fish with clinical signs of SVC.