Sequence comparison of the central region of the glycoprotein gene of neutralizable, non-neutralizable, and serially passed isolates of viral haemorrhagic septicaemia virus

The region of the viral haemorrhagic septicaemia virus glycoprotein g e n e coding for amino acids 142 to 357 was sequenced and compared among 6 isolates of the virus from rainbow trout in Denmark.Isolates were sclected that were strongly neutralized h) polyclonal and monoclonal antisera, not neutralized by antlsera, or that represented more than 500 serial passages in cell cultures The overall diversity within this region of the glycoproteln was 5 .4 % d t the nucleotide level and 6.9'%, at the amlno a c ~d level.Most of the variat~on was in the portion of the proteln from amiilo acids 210 to 290 where substitutions Lvert.found in 13 of the 80 amino acids (16':.,).In contrast, the central portion of the glycoprotein ot the F1 reference strain of the vlrus was remarkably stable during 510 passes in cell culture, accumulating only a single amino 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.