Deposition of Retrovirus Associated Antigens (p30 and gp70) on Cell Membranes of Feline and Murine Leukaemia Virus Infected Cells

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Abstract
Summary A quantitative estimation of retrovirus associated cell membrane antigens of murine and feline cells infected with their respective type C leukosis virus is presented. Using a radio-immune assay with three broadly reactive antisera, the minimum estimated number of retrovirus associated antigenic determinants on YAC [Moloney leukaemia virus (MuLV) infected murine] and FL-74 [feline leukaemia virus (FeLV) infected feline] cells was 1.3 × 106 and 1.6 × 106 determinants per cell respectively. The virus structural proteins p27–30 and gp70 were detected by three component specific antisera on murine and feline cell surfaces in amounts which varied between cell isolates. MuLV infected cells produced as many as 1.9 × 105 p30 antigenic determinants and 7.5 × 105 gp70 determinants on infected cells. FeLV infected cells (FL-74) expressed 5.6 × 105 p27 and 7.5 × 105 gp70 antigenic determinants per single cell surface. The major core protein (p27–30) and the major envelope glycoprotein (gp70) antigens are sufficiently physically separated on cell surfaces so that binding of either of the membrane antigens with component specific antibodies does not interfere with binding of antibodies specific for the other. Despite the expression of interspecies determinants for p30, gp70, and other retrovirus associated antigens detected by antibody procedures, interspecies determinants of cell mediated immunity could not be demonstrated in immune mice bearing Moloney sarcoma virus (MSV) induced tumours. Furthermore, xenogeneic immunization of mice with FL-74 cells failed to protect mice against the growth of MSV induced lymphoma or sarcoma.