Normal chicken cells (chf −) express a surface antigen which cross-reacts with determinants of the major envelope glycoprotein (gp85) of avian myeloblastosis virus

Using rabbit antisera raised against the purified major envelope glycoprotein (gp85) of avian myeloblastosis virus (AMV), we were unable to differentiate between normal chicken cells carrying the chicken-helper factor (chf +) from those lacking this endogenous virus information (chf −) in several serological assays, including competition radioimmunoassay and membrane immunofluorescence. Radioimmunoprecipitation analysis of the material recognized in uninfected chf(+) and chf(-) chicken cells by the rabbit anti-AMV gp85 antisera revealed the presence in immune precipitates of both cell types of a high molecular weight glycoprotein (∼125,000), while low amounts of gp85 were precipitated only from the chf(+) cells. In contrast, antisera raised against the gp85s of three other avian oncornaviruses did not recognize the 125,000-dalton molecule in either cell type, although gp85 was again precipitated from the chf(+) chicken cells. The high molecular weight glycoprotein (denoted NCG) appears to represent a normal chicken cell surface glycoprotein which is antigenically cross-reactive with unique determinants of AMV gp85, presumably dependent on the carbohydrate portion of the molecules. The significance of this cross-reactivity is discussed, as well as the interpretation of previous results obtained through the use of these rabbit anti-AMV gp85 antisera.