Figure 7.

Two models for gp120-independent HIV infection. Model 1: HIV may use cellular proteins that are anchored to its envelope to bind to either CLDN-7 or other proteins. In LNCaP, both CLDN-7 and associated proteins involved in gp120-independent infection are present. In 293T cells, neither CLDN-7 nor the other infection-related membrane protein(s) is present. Expression of CLDN-7 in 293T may increase infectivity, but the levels of infection of the CLDN-7-modified 293T may still be significantly lower than those for LNCaP. Model 2: HIV may use cellular proteins that are anchored to its envelope to bind to a CLDN-7-associated complex. Although transfection of CLDN-7 can express this protein on the cell surface, the lack of the CLDN-7-associated protein decreases the binding of virus to the target cells.