Fig. 1.

Nonproductive infection of oral keratinocytes by HIV-1. X4- or R5-tropic HIV-1 binds and internalizes into oral keratinocytes in a manner independent of the chemokine coreceptor specificity (CXCR4 or CCR5). A noncanonical HIV-1 receptor likely exists—perhaps, a surrogate for CD4. X4- and R5-tropic HIV-1 internalizes in the keratinocyte and uncoats, and viral RNA is reverse transcribed and integrates into the keratinocyte genome. Integration is stable, but new HIV-1 transcripts are not detected.