Contact sensitivity and tolerance induction to DNFB in experimental dengue virus infection.

Contact sensitivity and tolerance induction to 1-fluoro-2,4-dinitrobenzene (DNFB) were studied in mice infected with dengue virus at different stages of infection. It was observed that the contact sensitivity response throughout the period under study was unaltered when compared to control animals. When the tolerogen was given on the same day as the virus, the percentage tolerance induced in dengue-infected animals was the same as that seen in controls. However, when the tolerogen was administered 4 and 8 days after the virus inoculation, percentage tolerance rose significantly. Thus the presence of the virus in significant amounts was essential to cause enhanced tolerance. As it has been reported that tolerance to DNFB is induced by suppressor T cells, it is proposed that dengue virus enhances the activity of these cells.