DAO 49:117-122 (2002)  -  doi:10.3354/dao049117

Segment 8 encodes a structural protein of infectious salmon anaemia virus (ISAV); the co- linear transcript from Segment 7 probably encodes a non-structural or minor structural protein

Eirik Biering1,*, Knut Falk3, Eirik Hoel1,2, Jegatheswaran Thevarajan1, Maaike Joerink1, Are Nylund2, Curt Endresen2, Bjørn Krossøy1,2

1Intervet Norbio, Thormøhlensgt. 55, 5008 Bergen, Norway
2Department of Fisheries and Marine Biology, University of Bergen, 5020 Bergen, Norway
3National Veterinary Institute, 0033 Oslo, Norway

ABSTRACT: In this study we present the cloning, expression and partial identification of Genomic Segment 7 of infectious salmon anaemia virus (ISAV). The nucleotide sequence corresponding to Segment 7 was isolated from a bacteriophage lambda cDNA library and contained 2 overlapping open reading frames (ORFs) of 903 and 522 bases respectively. It also contained an ISAV-specific conserved nucleotide motif in the mRNA 5ยน region. The co-linear transcript representing the large ORF undergoes a splicing event that removes a 526 nucleotide intron to form a mRNA corresponding to the smaller reading frame. Thus, ISAV Genomic Segment 7 has a similar coding strategy as influenza A virus Segments 7 and 8. The largest ORF of Segment 7 and the first ORF of Segment 8 was expressed in E. coli as fusion proteins and rabbit antiserum was raised against the recombinant protein from Segment 8. Immunoblot studies using this antiserum and a serum against purified virus, show that Segment 8 encodes one of the major structural proteins of the virus whereas the co-linear ORF of Segment 7 probably encodes a non- or minor structural protein

KEY WORDS: ISAV · Splicing · Matrix · Segment 7 · Segment 8 · GenBank Accession No. AY044132

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