A comparison of Humanized mice models using NOD-derived strains for Dengue virus infection

Dengue, a major public health issue in tropical and subtropical regions, currently has no specific treatment and only one licensed vaccine, with limited use in endemic areas. The lack of antiviral drugs and the challenges in understanding dengue’s pathophysiology stem from the absence of an effective animal model that mirrors human infection in terms of viraemia peaks, clinical presentation, and immune response. Humanized mouse models have been useful in viral disease research, but dengue studies often use NOD-scid IL2R gamma null (NSG) immunodeficient mice, which focus on preventing graft rejection rather than fully developing human hematopoiesis. In this study, we compare four humanized mouse models derived from NOD mice expressing human cytokines, which were xenotransplanted and infected with DENV-2 (New Guinea C) intravenously. The models (Hu-NSG, hu-EXL, hu-SGM3) received xenotransplants of CD34+ fetal cord blood, while one model (Hu-SGM3-PBMCs) was transplanted with human PBMCs. We found that models expressing human cytokines had higher viremia compared to the NSG model. All the models showed infectious virus during viremia, confirmed by means of indirect plaque assays. The Hu-SGM3-PBMCs model, in particular, developed a severe infection with signs of bleeding and intestinal necrosis, leading to the death of all mice by day 18 post-infection, with viremia levels twice as high as in the other models according to RT-qPCR. The models using hCD34+ cells showed low or undetectable levels of human proinflammatory cytokines during infection, measured by means of flow cytometry Bead Arrays. In contrast, the hu-mice model with human PBMCs exhibited detectable and decreasing levels of IFN-g, IL-10, IP10, and TNF, which is consistent with the immune modulation seen in DENV-2 New Guinea C strain infections. These results indicate that humanized mice models derived from NOD mice expressing human cytokines enhance viremia and offer a relevant platform for studying dengue and potential treatments.