Figure 2.
Infected CD4+ T cells transmit the infection to the epithelial cell line HEp-2. A, Purified CD4+ T cells (1 × 106/mL) from cord blood (CB) were activated by phytohaemagglutinin (PHA) for 24 h, washed, and challenged by respiratory syncytial virus (RSV) at multiplicity of infection (MOI) of 0.5, for 1 h at 37°C. Cells were then washed and cultured for 3 days. After this time, cell supernatants (SN) were harvested, and CD4+ T cells were washed again. Then HEp-2 cell monolayers (40%/50% confluence) were directly exposed to RSV or to supernatants from infected CD4+ T cells or cocultured with infected CD4+ T cells (HEp-2/CD4+ T-cell ratio of 1:10) for 3 days. Then HEp-2 infection was analyzed by flow cytometry. B–D, HEp-2 cell monolayers (B) as well as purified CB CD4+ T cells (C) or Jurkat cells (D) previously activated for 24 h with 4 μg/mL of PHA were challenged with RSV (MOI, 0.5) in the absence or presence of heparin (50 U/mL) or ribavirin (80 µM). When indicated, cells were challenged with ultraviolet-treated RSV. In all cases, infection was revealed after 3 days of culture by flow cytometry. Representative experiments are shown in A (left), B (left), and C (left), and the mean ± SEM of 5 experiments are shown in A (right), B (right), C (right), and D. *P < .05, **P < .01 vs RSV+. Abbreviations: RSV, respiratory syncytial virus; SN, supernatant; UV, ultraviolet.