Human immunodeficiency virus type-1 susceptible whole cell and microcell hybrids

Expression of CD4, the principle receptor for HIV-1, is not sufficient for viral entry into most non-human and rare human cell lines. Construction of HIV-1 susceptible heterokaryons and a hybrid cone by fusion of HeLa cells and the HIV-1 resistant human cell line U373-CD4 were previously reported by us. These results suggested that U373-CD4 lack a cofactor(s) which is essential for HIV-1 entry and can be supplied by HeLa cells. Now the construction of multiple stable U373-CD4/HeLa whole cell and microcell hybrid clones are described, two of which are highly susceptible to HIV-1. Using these hybrids it is demonstrated that expression of CD4 and CD26, the T cell activation antigen dipeptidyl peptidase IV recently proposed as a CD4 cofactor necessary for HIV-1 infection, are not sufficient for HIV-1 entry. This panel of HIV-1 resistant and susceptible hybrids provides a rapid, simple assay for testing the role of other candidate cofactor molecules (e.g., fusin) that may be required for HIV-1 entry into human cells. Further, the method described by us for constructing HeLa microcells should permit the construction of murine-HeLa microcell hybrids, thus providing ideal reagents for determining which human chromosome(s) are needed to confer HIV-1 susceptibility onto non-human cells.