SEQUENCE COMPARISON OF THE CENTRAL REGION OF THE GLYCOPROTEIN GENE OFNEUTRALIZABLE, NON-NEUTRALIZABLE, AND SERIALLY PASSED ISOLATES OF VIRAL HEMORRHAGIC SEPTICEMIA VIRUS

The region of the viral haemorrhagic septicaemia virus glycoprotein ge ne coding for amino acids 142 to 357 was sequenced and compared among 6 isolates of the virus from rainbow trout in Denmark, Isolates were s elected that were strongly neutralized by polyclonal and monoclonal an tisera, not neutralized by antisera, or that represented more than 500 serial passages in cell cultures. The overall diversity within this r egion of the glycoprotein was 5.4% at the nucleotide level and 6.9% at the amino acid level. Most of the variation was in the portion of the protein from amino acids 210 to 290 where substitutions were found in 13 of the 80 amino adds (16%). In contrast, the central portion of th e glycoprotein of the Fl reference strain of the virus was remarkably stable during 510 passes in cell culture, accumulating only a single a mino acid substitution. Differences between the neutralizable and non- neutralizable isolates were found in the regions from amino acids 257 to 259 and from 283 to 288.