HIV phenotype correlates with the relative amounts of lymphocyte function-related molecule 1 (LFA-1) and major histocompatibility complex (MHC) class II in the virion envelope.

OBJECTIVE: The biological phenotype of HIV-1 has been associated with various aspects of its infectivity, including syncytium formation and coreceptor usage. Adhesion molecules, present on both the target cell and the virus, have also been shown to play a role in the infectious process. A possible correlation between the presence of adhesion molecules in the envelope of HIV-1 with the biological phenotype of the virus is examined.
DESIGN: The envelopes of 56 isolates of HIV-1 of known biological phenotype were analyzed for the presence of lymphocyte function-related molecule 1 (LFA-1) and major histocompatibility complex (MHC) class II molecules.
METHODS: The coreceptor usage of each isolate was determined in a GHOST cell or a U87.CD4 infectivity assay. The presence of LFA-1 and MHC class II in each virus envelope was then determined using a virus-binding enzyme-linked immunosorbent assay (ELISA).
RESULTS: Viruses using the chemokine receptor CCR5 have relatively higher levels of MHC class II than LFA-1 in their envelopes compared with those using CXCR4.
CONCLUSIONS: The finding that there is a differential incorporation of MHC class II and LFA-1 molecules by CXCR4- and CCR5-using viruses augments the list of properties contributing to the biological phenotype of HIV-1. This may explain, in part, how CXCR4-using viruses are able to bind to and infect a broader range of cell types than CCR5-using viruses, and why CXCR4-using viruses are associated with a more aggressive disease course.