Identification and characterization of viral structural proteins of infectious salmon anemia virus.
Infectious salmon anemia virus (ISAV) is an unclassified Orthomyxovirus that has been shown to contain a segmented genome with eight single-stranded RNA species coding for 10 viral proteins. Four major structural proteins were characterized in the present study: two glycosylated proteins with estimated molecular masses of 42 and 50 kDa, one 66-kDa phosphoprotein, and one 22-kDa protein. Examination of lysed virions revealed the two glycoproteins and the 22-kDa protein in the soluble fraction, while the 66-kDa phosphoprotein and a minor part of the 22-kDa protein were found in the pelleted fraction. Immunofluorescence staining of infected cells demonstrated that the 22-kDa protein was a late protein accumulating in the nucleus. We conclude that the 66-kDa protein is the nucleoprotein, the 22-kDa protein is the matrix protein, and the 42- and 50-kDa proteins are the surface proteins. Radioimmunoprecipitation analysis of the 42-kDa glycoprotein, which was previously shown to represent the ISAV hemagglutinin, indicated that this protein exists at least as dimers. Further, by labeling of purified ISAV with [1,3-(3)H]diisopropyl fluorophosphate, it was also demonstrated that the viral esterase is located with the hemagglutinin. This finding was confirmed by demonstration of acetylesterase activity in affinity-purified hemagglutinin preparations. Finally, the active-site serine residue could be tentatively identified at position 32 within the amino acid sequence of the hemagglutinin of ISAV strain Glesvaer/2/90. It is proposed that the ISAV vp66 protein be termed nucleoprotein, the gp42 protein be termed HE protein, and the vp22 protein be termed matrix protein.
Falk
Knut
K
Section for Fish Health, National Veterinary Institute, Oslo, Austria. Knut.Falk@vetinst.no
Aspehaug
Vidar
V
Vlasak
Reinhard
R
Endresen
Curt
C
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004950:Esterases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006384:Hemagglutination; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009975:Orthomyxoviridae / Q000378:metabolism*; D011233:Precipitin Tests; D020317:Salmo salar / Q000821:virology*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015678:Viral Structural Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014771:Virion / Q000378:metabolism
D015678:Viral Structural Proteins; D004950:Esterases