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.
Section for Fish Health, National Veterinary Institute, Oslo, Austria. Knut.Falk@vetinst.no
Knut
K
Falk
Vidar
V
Aspehaug
Reinhard
R
Vlasak
Curt
C
Endresen
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