Cell-associated HIV-1 infection of salivary gland epithelial cell lines

In this study we investigated the potential of cell-associated primary isolates of HIV-1 to infect epithelial cells of the oral cavity, using two cell lines originating in the salivary gland, HSY and HSG. Neither of these cell lines expresses surface CD4; however, both express the alternative epithelial receptor galactosylceramide and the coreceptor CXCR4. The ability of these cell lines to be infected via cell-associated infection was studied using a lab-adapted strain and primary isolates of HIV-1. Both HIV-1 phenotypes were able to infect these cell lines. The ligand for CXCR4 was able to block infection of both cell lines, whereas the ligands for CCR5 were able to block infection in HSY only, indicating that these receptors were utilized for entry into the epithelial cells. These findings demonstrate that epithelial cells of the oral cavity can be productively infected with HIV-1 by cell-borne virus in the absence of CD4.