Evidence for a Gp85-related glycoprotein in cells transformed by the Bryan high titer strain of Rous sarcoma virus.

The Bryan High Titer strain of Rous Sarcoma Virus (BH-RSV) is a deletion mutant in the env-gene coding for the viral envelope glycoproteins gp35 and gp85. In this report experimental evidence is described that cells, transformed by BH-RSV, express a glycoprotein immunologically related to gp85. Animals bearing BH-RSV induced tumors produce antibodies reacting with gp85 of nondefective RSV. Lysates of a BH-RSV transformed quail cell line, R(-):Q, inhibit the immunoprecipitation of gp85 by antibodies against the group-specific determinant of gp85. In R(-):Q cell lysates and in the culture supernatant a glycoprotein of an apparent molecular weight 40,000 (gp40) is found that reacts with monospecific antisera against gp85 of nondefective RSV. In newly synthesized BH-RSV a gp40 associated with the virion is detectable but is easily lost during purification of the virus. Further, a 95k glycoprotein and a 95k phosphoprotein are specifically precipitated from R(-):Q cells by an antiserum against gp85. From these results we conclude that the deletion of the env-gene is incomplete such that part of gp85, bearing group-specific antigenic determinants, is expressed in BH-RSV transformed cells. Analysis of BH-RSV particles freshly harvested from R(-):Q cells reveals that they contain almost exclusively the gag-precursor pr76 and little or no processed gag-proteins. Therefore the R(-):Q cell line seems to be suitable for the study of virus maturation occurring after the budding process.