The impact of chemokine receptor conformational heterogeneity on HIV infection.

Receptor binding largely governs viral tropism, since the presence of CD4 and an appropriate coreceptor is a prerequisite for membrane fusion and virus infection. Env-receptor interactions are conformationally complex, involving multiple regions in both gp120 as well as in the receptors. As a result, differences in receptor conformation, posttranslational processing, and surface density all have the potential to influence viral infectivity and therefore tropism and pathogenesis. This review gives an overview of the research that led to the discovery of chemokine receptors as coreceptors for HIV-1, describes the repertoire of coreceptors described to date and addresses their in vivo relevance. We will discuss very recent studies that indicate that while the presence of CD4 and coreceptor are necessary for virus infection, their mere presence is not sufficient.