SummaryRSV causes annual epidemics of bronchiolitis in winter months resulting in the hospitalization of many infants and the elderly. Dendritic cells (DCs) play a pivotal role in coordinating immune responses to infection and some viruses skew, or subvert, the immune functions of DCs. RSV infection of DCs could alter their function and this could explain why protection after natural RSV infection is incomplete and of short duration. In this study, this interaction between DCs and RSV was investigated using a human primary culture model. DCs were generated from purified healthy adult volunteer peripheral blood monocytes. Effects of RSV upon DC phenotype with RSV primed DCs was measured using flow cytometry. Changes to viability and proliferation of cocultured DCs and T-cells were determined using microscopy with fluorescent dyes (Hoechst 33342 and propidium iodide). DC maturation was not prevented by the RSV challenge. RSV infected a fraction of DCs (10-30%) but the virus replicated slowly in these cells with only small reduction to cell viability. DCs challenged with RSV stimulated T-cell proliferation less well than lipopolysaccharide. This is the first study to demonstrate RSV infection of human monocyte derived DCs and suggests that the virus does not significantly interfere with the function of these cells and potentially may promote cellular rather than humoral responses.

SummaryThe annual epidemics of respiratory syncytial virus (RSV) infection are probably explained by poor herd immunity and the existence of a dormant reservoir of virus that is activated by an unknown trigger. The virus causes particular problems in infants, the elderly and patients with chronic obstructive airways disease (COPD). During two consecutive winters, human monocyte-derived dendritic cells (DCs) were exposed on a single occasion to one of two forms of RSV labelled with a fluorescent expresser genes (rgRSV or rrRSV) during the epidemic season. The cultures were maintained for many months, with fresh DCs being added at monthly intervals. The cultures were variously exposed to 600 parts per billion (

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