Retention of HIV-1 inside infected MOLT-4 cells in association with adhesion-induced cytoskeleton reorganization

Objective: To study the mechanism of the suppression of HIV release during cell-to-cell adhesion. Design and methods: To investigate the effects of cell-to-cell adhesion on HIV release in association with cytoskeletal elements, chronically HIV-infected T cells were cocultured with different adherent cell lines, cultured on a fibronectin-coated surface, or treated with cytochalasin D. The amount of viral protein released in the culture supernatant and retained inside the cells was monitored by a p24 enzyme-linked immunos-orbent assay and Western blotting. For F-actin staining, cells were stained with FITC-labelled phalloidine and examined by immunofluorescence microscopy. Results: Cocultivation resulted in a reduced amount of virus in the culture supernatant and induced the retention of viral protein inside the infected cells. On adhesion to cells, the F-actin of the infected cells was polarized towards the cell periphery from a diffuse cytoplasmic distribution. Similar data were obtained when the infected cells were treated with cytochalasin D or adhered to fibronectin. Conclusion: Cell-to-cell adhesion induced polarization of F-actin, which might facilitate HIV retention inside infected T cells.