Abstract
The 15,000-molecular-weight polypeptide (p15) of feline leukemia virus (FeLV) was shown to impair normal lymphocyte function in vitro and to abrogate immunity to feline oncornavirus disease in vivo. FeLV p15 suppressed concanavalin A-induced blast transformation of normal feline lymphocytes by 68%, while other virion proteins had no effect. p15 suppression was not due to toxicity, nor was p15 a competitive inhibitor of concanavalin A binding. Capping of receptors for concanavalin A on normal feline lymphocytes also was inhibited by either inactivated FeLV or FeLV p15.
Groups of cats were immunized with either killed feline oncornavirus-associated cell membrane antigen bearing tumor cells or tumor cells plus FeLV p15. After challenge with feline sarcoma virus, three of four p15-treated cats developed progressive fatal fibrosarcoma as compared to one of five non-p15-treated cats. The cats receiving p15 also had lower cytotoxic antibody titers against feline oncornavirus-associated cell membrane antigen (mean peak titer, 1:6) than did the non-p15 group (1:74). These data support the hypothesis that the immunosuppression in cats infected with FeLV is mediated by FeLV p15.
Footnotes
-
↵1 Supported in part by USPHS Contract NO 1 5-3571 and CP-VO-81035-63 from the Division of Cancer Cause and Prevention of the Virus Cancer Program and by Grant CA-15147-03 from the National Cancer Program of the NIH.
-
↵2 To whom requests for reprints should be addressed, at Department of Veterinary Pathobiology, The Ohio State University, 1925 Coffey Road, Columbus, Ohio 43210.
- Received June 21, 1978.
- Accepted December 1, 1978.
- ©1979 American Association for Cancer Research.
Volume 39, Issue 3
