6th IAS Conference On HIV Pathogenesis, Treatment and Prevention


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MOAA0102 - Oral Abstract Session

The PI3K signaling pathway is critical for HIV integration in latently infected resting CD4+T-cells

Presented by Suha Saleh (Australia).

S. Saleh1, P. Cameron1,2, G. Sallmann1, A. Joworowski1,3, S. Lewin1,2,3

1Monash University, Medicine, Melbourne, Australia, 2Infectious Disease Unit of Alfred Hospital, Melbourne, Australia, 3Burnet Institute, Melbourne, Australia

Background: We recently showed that latency can be established in resting CD4+ T cells following incubation with chemokines that bind to CCR7, CXCR3 and CCR6 receptors that are highly expressed on resting CD4+ T cells. Receptor ligation allowed for increased efficiency of nuclear localization and integration of HIV DNA in resting CD4+ T-cells. We hypothesised that activation of specific signaling pathways including the phosphoinositol 3 kinase (PI3K) allowed for efficient nuclear localization and viral integration in resting CD4+ T-cells.
Methods: Resting CD4+ T-cells were incubated with either CCL19, PHA/IL-2 or unactivated for 24 hours and then infected with HIV-1 in the presence or absence of pharmacological inhibitors of the PI3K pathway. q PCR was used to quantify 2-LTR circles (as a marker of nuclear localization) and integrated HIV DNA at day 4 post-infection. To detect activation of the PI3K/AKT pathway, cells were stimulated with CCL19 +/- the inhibitors and analysed Akt phosphorylation by immunoblotting.
Results: Infection of cells in the presence of CCL19, PHA/IL-2 or no activation led to a mean of 11 916, 71 000 and < 300 integrated copies/million cells and 25 333, 154 500 and 74 132-LTR copies/million cells respectively. Incubation of cells with CCL19 and the pan PI3K inhibitors Ly294002 and wortmannin, or specific down streams inhibitors PD98059 (ERK1/2), SP600125 (JNK), SC-514 & BAY11-7082 (NF-kB), completely eliminated integrated DNA but only slightly changed 2-LTR. Inhibition of the AKT pathway with SB203580, a compound inhibiting p38 kinase activity had no effect on viral integration. Ly294002 and wortmannin were active as confirmed by complete blocking of Akt phosphorylation in response to CCL19.
Conclusion: In our model of chemokine induced latency, efficient integration in resting CD4+ T-cells was mediated by the PI3K pathway. Strategies that target these pathways may potentially lead to novel interventions to block the establishment of latent infection.

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