Species tropism of HIV-1 infectivity of interspecific cell hybridomas implies non-CD4 structures are required for cell entry.

Studies have demonstrated that CD4 may be necessary but not sufficient for human immunodeficiency virus (HIV) infection. Murine cell lines constructed to express the human CD4 glycoprotein demonstrate a restriction in their ability to support infection by the HIV-1 retrovirus. Such restrictions may indicate that molecules in addition to CD4 may be necessary for HIV-1 infection. HIV-1 infectivity has been examined in a panel of murine and human cell lines. It has been demonstrated that CD4 expression allows infectivity on a wide range of human cell lines. Some interspecific hybridomas constructed between human and murine cell lines can, when expressing the human CD4 glycoprotein, become infectable in a manner similar to human cell lines. These studies imply that surface molecules, in addition to CD4, are necessary for HIV-1 entry and infectivity. Such molecules will be important for understanding the pathogenesis of HIV-1.