HIV reactivation from latency is induced by cytokines but also by cell contact with other cells. To better understand this, J1.1 cells, a latent HIV-1-infected Jurkat derivative, were cocultured with its parental Jurkat. J1.1 cells became p17MA-positive and produced a high level of HIV p24CA antigen, only when they were cocultured with stimulated Jurkat with cell-to-cell contact. In contrast, very little p24CA was produced when they were cocultured without cell contact. Similar results were obtained when latent ACH-2 and its parental A3.01 cells were cocultured. Confocal microscopy revealed that not only HIV-1 p17MA and gp120Env but also LFA-1, CD81, CD59, and TCR CD3 accumulated at the cell contact site, suggesting formation of the virological synapse-like structure. LFA-1-ICAM-1 interaction was involved in the cell-to-cell contact. When J1.1 was cocultured with TCR-deficient Jurkat, the p17MA-positive rate was significantly lower, although the cell-to-cell contact was not impaired. Quantitative proteomics identified 54 membrane molecules, one of which was MHC class I, that accumulated at the cell contact site. Reactivation from latency was also influenced by the presence of stromal cells. Our study indicated that latent HIV-1 in J1.1/ACH-2 cells was efficiently reactivated by cell-to-cell contact with stimulated parental cells, accompanying the virological synapse-like structure.
Keywords: HIV-1; cell-to-cell contact; latency; reactivation; virological synapse.