A complete picture of what the HIV-1 envelope spike looks like before it binds to target cells is reported in Nature this week. This spike facilitates entry of the virus into cells, and the pre-fused state is what the host immune system would detect; thus, examination of the structure may aid the design of vaccines that elicit protective immune responses to this spike.
The surface, or envelope, of the HIV-1 virus is covered in spikes that fuse with host cells and initiate infection. The HIV-1 envelope spike is a target for vaccine efforts, but has successfully evaded most antibody-mediated neutralization. Over the past 20 years, information about portions of this structure has been gathered, but the high-resolution complete pre-fusion structure presented by Peter Kwong and colleagues provides new opportunities to study the spike. The new structure provides more insight into how the spike functions to enable fusion to cells. Moreover, analyses reveal how the spike evades immune responses, and highlights features that could be recognized by the immune system, which may aid future attempts to develop new vaccines.