Characterization of a unique protein produced by influenza A virus recovered from a long-term persistent infection.
Virus isolated from a persistent infection initiated in BHK cells with influenza A/WSN/33 (H1N1) produced an unusual pattern of protein synthesis in productive infections of BHK cells: The levels of NP and M1 proteins were slightly reduced compared to an infection with wild-type WSN, while the other proteins (Pb1, Pb2, Pa, HA, NS1, and NS2) were synthesized at very low or undetectable levels. In addition, a new viral protein with an approximate molecular weight of 11 kDa (Pi protein) is made (Frielle et al., Virology 138, 103-117, 1984). When viral RNA was analyzed by the Northern blot technique, a deletion was found in the NS gene segment and in NS1 mRNA; all other RNAs were full-sized. Immunoprecipitation of in vitro translation products demonstrated that the Pi protein reacts specifically with anti-NS1 serum. In addition, the Pi protein, like the NS1 of the parental wild-type virus, accumulated in the nucleus of infected cells. These results indicate that the Pi protein is a mutated form of the NS1 protein encoded by a deleted NS segment and suggest that this mutation may be involved in the expression of the persistent virus phenotype.
Lucas
W T
WT
Department of Microbiology, Biochemistry and Molecular Biology, University of Pittsburgh, School of Medicine, Pennsylvania 15261.
Whitaker-Dowling
P
P
Kaifer
C R
CR
Youngner
J S
JS
D000818:Animals; D015152:Blotting, Northern; D002213:Capsid / Q000032:analysis* / Q000235:genetics; D002460:Cell Line; D006224:Cricetinae; D005814:Genes, Viral; D009980:Influenza A virus / Q000032:analysis* / Q000235:genetics; D009154:Mutation; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics; D009976:Orthomyxoviridae Infections / Q000382:microbiology*; D011233:Precipitin Tests; D013997:Time Factors; D014758:Viral Core Proteins / Q000032:analysis* / Q000235:genetics; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins / Q000032:analysis* / Q000235:genetics
D009687:Nuclear Proteins; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins