Persistent Dengue Infection in an Immunosuppressed Patient Reveals the Roles of Humoral and Cellular Immune Responses in Virus Clearance.

Detailed understanding of the roles of humoral and cellular immune responses in sterilizing dengue virus (DENV) infection in humans is required to inform effective vaccine development. We report an unusual case of persistent DENV infection in a lymphopenic renal transplant recipient who was therapeutically immunosuppressed to prevent organ rejection. Following resolution of symptomatic dengue, this patient remained positive for DENV3 RNA in the blood for 4 months and viruric up to 9 months post-infection despite demonstrable levels of serum neutralizing antibodies throughout this period. Full resolution of DENV infection instead coincided with recovery of CD8+ T cell counts during reversal from lymphopenia. Taken collectively, our observations suggest a role for cellular immunity in sterilizing DENV infection in humans. Any dengue vaccine should thus be able to induce both humoral and cellular immunity that respectively prevent symptomatic infection and enable effective viral clearance.