Detection of novel strains of cyprinid herpesvirus closely related to koi herpesvirus

Cyprinid herpesvirus 3 (CyHV-3) or koi herpesvirus (KHV) is a devastating virus of carp. Using generic primers for the DNA polymerase and the major capsid protein genes of cyprinid herpesviruses, nucleotide sequences divergent from previously described CyHV-3 were obtained. At least 3 novel groups of putative CyHV-3-like viruses were identified, sharing 95 to 98% nucleotide identity with CyHV-3 strains. Carp carrying the CyHV-3 variants did not show clinical signs consistent with CyHV-3 infection and originated from locations with no actual CyHV-3 outbreaks. These strains might represent low- or non-pathogenic variants of CyHV-3.