COMPARATIVE SUSCEPTIBILITY OF 3 SPECIES OF CHAR AND OF RAINBOW-TROUT X CHAR TRIPLOID HYBRIDS TO SEVERAL PATHOGENIC SALMONID VIRUSES

Triploid hybrids were obtained from rainbow trout Oncorhynchus mykiss females crossed with sires of brook trout Salvelinus fontinalis, arctic char S. alpinus and lake trout S. namaycush following heat-shock-provoked retention of the second polar body. Survival rates of hybrids obtained were ca 50 %. The hybrids and the parental species were challenged with infectious pancreatic necrosis virus (IPNV) type Sp, viral haemorrhagic septicaemia virus (VHSV) types 1 and 3, and infectious haematopoietic necrosis virus (IHNV). Rainbow trout x coho salmon (O. kisutch) triploid hybrids were included in certain infection trials. The results indicated that brook trout were resistant to VHSV, and brook trout x rainbow trout hybrids were resistant to both VHSV and IHNV, but susceptible to IPNV. Arctic char were susceptible to IPNV and resistant to VHSV. The hybrids were susceptible to IPNV, but partially resistant to VHSV. Lake trout were partially resistant to IPNV, but their hybrids with rainbow trout were susceptible. Lake trout infected by VHSV showed clinical signs, and significant losses resulted.