Unveiling the Dynamic Interactions of HIV Proteins with CD4 Receptors

Researchers have used cryo-electron microscopy to study the intermediate conformations of HIV-1 Env glycoprotein, which plays a crucial role in the entry of the virus into host cells. They designed soluble Env heterotrimers that can bind one or two CD4 receptors and compared them to closed and fully saturated CD4-bound open trimers. The study revealed that binding one CD4 receptor resulted in a closed, prefusion conformation, while binding two CD4 receptors induced an asymmetric, partially open conformation. These findings provide insights into the conformational changes of Env and the fusion process of HIV-1.