FIG. 5.

Proposed model to explain the higher susceptibility of T cells expressing the activated form of LFA-1 to infection with ICAM-1-bearing virions. (A) Without any complementary interactions, the gp120/CD4 association enables the virus to attach to target cells with relatively high affinity. (B) The presence of additional interactions, such as that between virion-incorporated ICAM-1 and cell surface LFA-1, will increase the efficiency of viral binding and accelerate the process of virus entry. (C) In the context of cellular activation, the high-affinity LFA-1 on the surface of target cells will permit the ICAM-1-bearing viruses to attach more firmly to and enter the host cell more rapidly.