Reovirus transport--studies using lymphocytosis promoting factor.

To explore how bacteria and their products may modulate viral infection, we investigated the effect of a well-characterized and highly purified product of Bordetella pertussis, a pertussis toxin, also known as lymphocytosis promoting factor (LPF), on enteric reovirus infection. LPF is known to have a variety of effects, including modulation of circulation and homing of lymphoid cells. When adult mice are inoculated with reovirus type 1 perorally, reovirus first enters the Peyer's patches (PP) through M cells, and then spreads to mesenteric lymph nodes (MLN) and spleen with minimal dissemination to other peripheral tissues. In view of the profound effect of LPF on lymphoid tissues, we evaluated whether LPF might influence the early stages of type-1 reovirus infection following peroral inoculation. Pretreatment of adult BALB/c mice with LPF significantly inhibited the spread of reovirus in a manner dependent upon the route of inoculation; LPF inhibited the extra-intestinal spread of virus from PP to MLN after intragastric inoculation; in contrast there was enhancement of the spread of blood-borne viruses to MLN after intravenous inoculation. This result, together with the fact that the efferent lymph from PP reaches MLN, suggests that a proportion of reoviruses were conveyed from PP to MLN in association with lymphoid cells along the lymphatic channels and that LPF affects reovirus, in part, by blocking cell movement.