Functional evaluation of HIV/SIV Nef as superantigen

It is speculated that a virus-encoded superantigen is involved in the patho genesis of human and simian immunodeficiency virus infections and that the accessory protein Nef might be that superantigen. We are able to show, usin g a murine superantigen screening system, that Nef does nor display feature s characteristic of a superantigen. Upon transfection into MHC class II exp ressing antigen-presenting cells, it is expressed, but fails to induce VP-s pecific expansion of peripheral T lymphocytes, which is a characteristic fe ature of superantigens in mixed lymphocyte culture. Therefore, we cannot su pport the hypothesis that Nef is a superantigen. The observations in favor of that hypothesis must be explained by other mechanisms. (C) 2001 Academic Press.