P14. Increased replication following evolution of PYxE insertion in ALIX-binding motif in Gag-p6 associated with enhanced virulence in HIV-1 subtype C.

Shambhu Aralaguppe1, Miguel E. Quinones-Mateu2, Anders Sonnerborg1, Ujjwal Neogi1

Affiliates: 1Karolinska Institutet, 2Case Western Reserve University

Background
Contradictory results have been reported on the impact of duplications in the HIV-1 Gag-p6 late assembly domain (L-domain); TSG101-binding P(T/S)APP-motif on the response to antiretroviral therapy (ART). We recently observed a novel HIV-1 subtype C (HIV-1C) specific PYxE insertion in another L-domain of human ALIX-binding site, associated with PI-failure was observed in HIV-1CIN strains, but occurred naturally in wild-type Ethiopian HIV-1C (HIV-1ET) strains. The aim of the present study is to characterise the viruses’ replication with the specific insertion phenotypically as well as phenotypic drug sensitivity assay to twenty antiretroviral belonging to reverse transcriptase (RTI), protease (PI) and integrase inhibitors (INI).

Methods
p2-INT region from virus gag-pol region was cloned into pNL4-3 (HIV-1B) backbone from three HIV-1C and one HIV-1B infected patient. Viral growth kinetics was measured using quantification of functional reverse transcriptase enzyme. Phenotypic drug sensitivity assay was performed in MT4 cells.

Results
The accumulation of PYxE in the p6 of HIV-1C viruses, showed increase in the replication capacity compared to viruses that does not contain the insertion (wild type) (Fig 1). However there is no effect of phenotypic drug susceptibility against the 20 drugs tested (Table 1).

Conclusions
Based on our proof-of-concept study, we therefore hypothesise that that HIV-1C strains with PYxE insertion are more replication competent than strains without the insertion and has increased its virulence leading to a rapid progression to AIDS. As observed earlier the patients with PYxE-insertion have less CD4 cell count it may affect the immune reconstitution but may not have effect in the therapy response.

19. Shambhu_Figure