Effect of interferon on mouse leukaemia virus (MuLV). V. Abnormal proteins in virions of Rauscher MuLV produced in the presence of interferon

Abstract

Interferon treatment of JLSV-6 cells chronically infected with Rauscher MuLV leads to the formation of non-infectious particles ('interferon ' virions) containing the structural proteins coded by the env and gag genes as well as additional virus polypeptides. The major glycoprotein detected in the control virions is gp7I, but 'interferon ' virions contain in addition an 85K mol. wt. (gp85) glucosamine-containing, fucose-deficient glycoprotein. This is recognized by antiserum to MuLV and may be related to env pr85. Surface iodination of intact virions in-dicates that gp7I and gp85 are the two major components ofthe external envelope. However, whereas in control virions gp7I associates with pI5 E (gp9o), this complex was not detected in 'interferon ' virions. Analysis of radio-labelled (all-amino acids or iodinated) proteins from disrupted 'interferon ' virions revealed the presence of 65K, 55K, 4oK, 2oK and I2K mol. wt. polypeptides which could be precipitated with antiserum against MuLV. There was a distinct difference in the patterns of in-corporation of pulse-labelled 3H-amino acid polypeptides into virions in the presence and absence of interferon. Those polypeptides labelled in the presence of interferon and recovered in the extracellular virions in a chase with interferon appeared to have substantially fewer copies of p3o and more of gag pr55 poly-peptide than the controls. These results indicate that in the presence of interferon there are changes in the proteolytic cleavage associated with virion assembly