Immunolocalization studies of an antisense protein in HIV-1-infected cells and viral particles.

The minus DNA strand of HIV-1 presents an open reading frame that is complementary to the HIV-1 envelope messenger, is highly conserved among HIV-1 isolates, and may encode a hydrophobic protein. In previous studies, the antisense transcript has been identified both in various HIV-infected cell lines and in leukocytes of HIV-1(+) patients. The expression of the corresponding antisense protein (ASP) during natural HIV-1 infection has been indirectly evidenced by the identification of anti-ASP antibodies in the sera of HIV(+) patients. We have used immunoelectron microscopy procedures (ultra-small gold particles coupled to silver enhancement) to establish direct evidence of ASP production. ASP has then been detected in chronically and acutely HIV-1-infected cell lines. The protein, found mostly associated with various cellular membranes as well as with the virions released from the cells, indicated that ASP is a bona fide component for the virions and may participate in the particle formation.