NEUTRALIZATION EPITOPES ON HIV PSEUDOTYPED WITH HTLV-I - CONSERVATIONOF CARBOHYDRATE EPITOPES

One mechanism for expanding the cellular tropism of human immunodefici ency virus (HIV) in vitro is through formation of phenotypically mixed particles (pseudotypes) with human T lymphotropic virus type I (HTLV- I). In this study we found that pseudotypes allow penetration of HIV p articles into CD4-negative cells, previously nonsusceptible to HIV inf ection. The infection of CD4-negative cells with pseudotypes could be blocked with anti-HTLV-I serum but failed to be significantly inhibite d with anti-HIV serum or a V-3-neutralizing anti-gp120 monoclonal anti body. This may represent a possibility for pseudotypes to escape neutr alization by the immune system in vivo. Previous reports have suggeste d that carbohydrate structures may be conserved neutralization epitope s on retroviruses. In this study, the neutralizing capacity of lectins and anti-carbohydrate monoclonal antibodies was found to block infect ion by cell-free pseudotypes in CD4-negative cells. We suggest that al though viral cofactors might expand the tropism of HIV in vivo, HIV an d HTLV-I seem to induce common carbohydrate neutralization epitopes.