Effect of experimental dengue virus infection on humoral and cell-mediated immune response to thymus-dependent antigen.

Mice injected with dengue virus showed a depressed primary and secondary humoral immune response to SRBC as measured by the number of antibody-forming cells, haemagglutinin and haemolysin titres. The time of administration of SRBC during the infection was found to be an important factor determining the response to SRBC. The cell-mediated immune response was also suppressed as measured by the delayed hypersensitivity reaction to SRBC in the footpad. While the immunosuppression of humoral immunity was only transient and the animals recovered within 30 days following infection, the cell-mediated immunity remained suppressed throughout this period. Immunofluorescent studies and LD50 determination of the infected brains demonstrated significant virus titres from 7 to 15 days postinfection. This period coincided with maximal immunosuppression.