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The role of CCL19 and CCL21 in HIV infection and latency in CD4+ resting T cells
Presented by Suha Saleh, Australia.
Saleh S.1, Solomon A.1, Wightman F.1, Xhilagal M.1, Cameron P.1, Lewin S.2
1Monash University, Medicine Department, Melbourne, Australia, 2Infectious Disease Unit, Alfred Hospital, Melbourne, Australia
Objectives: Resting CD4+ T cells found in lymphoid tissue are relatively permissive to HIV infection both in vivo and ex vivo while resting CD4+ T cells found in peripheral blood are resistant to HIV infection. We have investigated the role of CCL19 and CCL21 homeostatic chemokines in HIV infection of resting CD4+ T cells.
Methods: Highly purified resting CD4+ T cells were incubated with CCL19, CCL21 then infected with HIV-1. Reverse transcriptase (RT) activity was quantified in culture supernatants and integrated HIV-1 DNA was quantified at day 4 post-infection using a nested real-time PCR assay. Production of replication-competent virus from the infected cells was examined using a second round of activation in the presence and absence of the integrase inhibitor L8 (Merck).
Results: Both CCL19/CCL21 either alone or in combination led to infection of resting CD4+ T cells in the absence of cell activation. Low levels of RT were detected 7 days following infection (72+/-25 cpu/ml; mean+/-SE) of CCL19/21 conditioned T cells compared with PHA/IL2 stimulated cells (1625+/-460.8 cpu/ml). A high concentration of integrated HIV-1 DNA was demonstrated 4 days following infection in resting CD4+ T cells pretreated with 10 nM CCL19/CCL21 compared with stimulation with PHA/IL2 (n=4; median = 29,000 copies per million cells and 200,000 copies/million cells respectively). Following a second round of cell activation of CCL19-treated cells, there was a significant increase in RT production both in the presence of and absence of L8 indicating that replication competent virus in CCL19-treated cells was derived from integrated HIV-1.
Conclusions: Stimulation of resting CD4+ T cells with CCL19 and CCL21 leads to a high level of HIV-1 integration and low level of productive HIV-1 infection in the absence of cell activation. CCL19 and CCL21 may be critical chemokines in the lymph node environment that allow HIV-1 infection of resting CD4+ T cells and the establishment of latency.
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