Figure 6.

CCR5-dependent cell-to-cell transfer of infectious HIV-1. TERT-2 cells were pre-incubated with P. gingivalis or untreated and then inoculated with (A) R5- and (B) X4-HIV-1. The protocol is as described in the Materials and Methods and summarized in the legend of Fig. 1. Cells were trypsinized, washed, and lysed. The lysates were assayed for HIV p24 by ELISA. Similarly, TERT-2 cells were pre-incubated with P. gingivalis or untreated and then incubated with (C) a 1:10 dilution of 200 μg/mL anti-CCR5 antibody or (D) with 30 ng/mL or 300 ng/mL of the CCR5 inhibitor RANTES, and R5-HIV-1 for 6 h (in the presence of the antibody or RANTES). At 18 h post-inoculation, oral keratinocytes were detached with trypsin, washed twice and seeded onto TZM-bl cells for co-culture. Data represent the mean ± SEM from 3 independent experiments, each performed in triplicate. * p-value < 0.05, ** p-value < 0.001. (E) Photomicrographs of X-gal stained cell co-cultures of TERT-2 cells pre-incubated with P. gingivalis and infected with Ba-L for 6 h (I, II and III) as described above. In the co-cultures with TZM-bl cells, arrows identify some proximal TERT-2 cells (panels II and III). Positive control Ba-L-inoculated TZM-bl cells co-cultured with TZM-bl cells are also shown (IV). In panel IV, the arrow shows a multinucleated TZM-bl cell.