Virus Hijacks Host Proteins and Machinery for Assembly and Budding, with HIV-1 as an Example.

Viral assembly and budding are the final steps and key determinants of the virus life cycle and are regulated by virus-host interaction. Several viruses are known to use their late assembly (L) domains to hijack host machinery and cellular adaptors to be used for the requirement of virus replication. The L domains are highly conserved short sequences whose mutation or deletion may lead to the accumulation of immature virions at the plasma membrane. The L domains were firstly identified within retroviral Gag polyprotein and later detected in structural proteins of many other enveloped RNA viruses. Here, we used HIV-1 as an example to describe how the HIV-1 virus hijacks ESCRT membrane fission machinery to facilitate virion assembly and release. We also introduce galectin-3, a chimera type of the galectin family that is up-regulated by HIV-1 during infection and further used to promote HIV-1 assembly and budding via the stabilization of Alix-Gag interaction. It is worth further dissecting the details and finetuning the regulatory mechanism, as well as identifying novel candidates involved in this final step of replication cycle.