Characterizing the role of HIV-1 p6-Alix binding in HIV-1 replication

Wednesday, October 26, 2011 — Poster Session IV
2:00 p.m. – 4:00 p.m.	Natcher Conference Center	NCI	VIROL/MICRO-13

* FARE Award Winner

Authors

• L Kuo
• K Fujii
• E Freed

Abstract

The central question of how HIV-1 utilizes host cellular ESCRT (Endosomal Sorting Complex Required for Transport) machinery to enhance virus replication is critically important to our understanding of HIV-1 virus assembly and release. We have dissected the interaction between HIV-1 Gag and the host cellular ESCRT-associated protein, Alix. The p6 domain of HIV-1 Gag is required for virus budding. Motifs in HIV-1 p6 promote the release of virions from infected cells by interacting directly with host cell factors, such as Alix. Mutations in the p6-Alix binding site resulted in a profound HIV-1 replication delay in Jurkat T cells. This exciting observation drove us to further ascertain the nature of the replication defect imposed by the binding site mutations. Passaging of the HIV-1 mutants defective for Alix binding led to the emergence of revertant viral isolates that displayed wildtype replication kinetics. Sequencing revealed several putative compensatory mutations mapping to the HIV-1 Env and Vpu. We confirmed these mutations do indeed compensate for the defects of the p6 mutations on virus replication. We have extensively characterized the effects of the mutations on virus infectivity. Altogether, this study has advanced our mechanistic understanding of how HIV-1 usurps host ESCRT machinery.

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