Genetic comparison of viral hemorrhagic septicemia virus isolates from North America and Europe

Viral hemorrhagic septicemia virus (VHSV) is the cdusative agent of a serious rhabdoviral d ~ s e a s e of rainbow trout Oncorhynchus myklss in Europe The first isolation of the vlrus in North Amenca occurred In the fall of 1988 when it was recovered from adult chinook 0 tshawytscha and coho 0 klsutch salmon returning to 2 ha tcher~es in the state of Washington, USA The following year, VHSV was isolated from adult coho salmon at 2 other ha tcher~es in northwestern Washington In 1990 and 1991, VHSV was recovered from Pacific cod Gadus macrocephalus caught in Pnnce Willlam Sound, Alaska Genetic vanation among the 4 isolates from salmon and the 1990 ~sola te from Pacific cod was de t e rm~ned uslng T1 nbonuclease finqerprlnt~ng In addition, 4 d~ve r se isolates from Europe were lncluded for companson The North Amencan isolates of VHSV formed a slngle fingerprint group In which the 4 isolates from salmonids were h ~ g h l y similar to each other and the isolate from Pacific cod was related but less s~milar The 4 European ~sola tes which included an isolate from Atlantic cod G morhua, formed a second fingerpnnt group The genetic d ~ v e r s ~ t y among the isolates within each fingerpnnt group was estimated to be less than 5 % whlle the North Amencan and European strains of the virus were judged to differ by more than 5% The results indicate that the North Amerlcan isolates of VHSV are not of European ongln and that the virus may be enzootic wlthin the manne environment