Antibodies to the nef protein and to nef peptides in HIV-1-infected seronegative individuals.

The silent period that follows infection by the human immunodeficiency virus (HIV-1) and precedes seroconversion remains a problem for the screening of blood supply, and knowledge about the mechanism involved in the maintenance of latency is only fragmentary. Using purified nef recombinant protein and six synthetic nef peptides, antibodies to the product of an HIV-1 regulatory gene, the negative regulatory factor (nef) involved in maintenance of proviral latency, were detected by Western blot and radioimmunoassay techniques in HIV-1-seronegative, viral antigen-negative, and virus culture-negative individuals at risk for HIV infection. This antibody response to nef was correlated in eight individuals with the detection of HIV-1 proviral DNA by oligonucleotide hybridization, following enzymatic amplification of HIV DNA in peripheral blood mononuclear cells. Such latent HIV infections have now been followed for up to 6 or 10 months in five individuals. In addition, retrospective and prospective analysis of HIV-1-seropositive individuals have shown (1) antibodies to nef preceding seroconversion, and (2) the persistence of antibodies to nef and of HIV-1 proviral DNA in a case of spontaneous complete HIV-1 seronegativation. Since DNA amplification cannot be currently considered for routine use, screening for anti-nef antibodies followed by confirmation by DNA amplification could represent a basis for new diagnostic strategies. Beyond their diagnostic implications, these findings, suggesting that regulatory genes of the HIV-1 provirus can be expressed prior to the initiation of virion synthesis, may also be applicable in the design of alternative vaccines against the acquired immunodeficiency syndrome.