Comparative pathogenicity of two strains of pike fry rhabdovirus and spring viremia of carp virus for young roach, common carp, grass carp and rainbow trout

A field isolate of pike fry rhabdovirus (PFR-80560) isolated from roach was tested for pathogenicity in fry of roach Rutilus rutilus L., common carp Cyprinus carpio L., grass carp Ctenopharyngodon idella Valenciennes and rainbow trout Oncorhynchus mykiss Richardson. The fish were experimentally exposed to the virus by immersion in a virus-seeded water-bath. We also compared the pathogenicity of PFR-80560 with that of reference strains of PFR and spring viremia of carp virus (SVCV). The PFR-80560 isolate was highly pathogenic for roach, common carp and grass carp, but not for rainbow trout. Although the PFR reference strain was mildly pathogenic for roach, i t was no longer pathogenic for pike fry which may represent attenuation due to its numerous passages in cell culture. The SVCV was highly pathogenic for common carp, mildly pathogenic for roach and grass carp, but not pathogenic for rainbow trout. It was concluded that since the PFR-80560 isolate was capable of infecting all the cyprinids tested, it should be considered as a threat to cyprinid fish farms.