Human immune cell engraftment does not alter development of severe acute Rift Valley fever in mice.

Rift Valley fever (RVF) in humans is usually mild, but, in a subset of cases, can progress to severe hepatic and neurological disease. Rodent models of RVF generally develop acute severe clinical disease. Here, we inoculated humanized NSG-SGM3 mice with Rift Valley fever virus (RVFV) to investigate whether the presence of human immune cells in mice would alter the progression of RVFV infection to more closely model human disease. Despite increased human cytokine expression, including responses mirroring those seen in human disease, and decreased hepatic viral RNA levels at terminal euthanasia, both high- and low-dose RVFV inoculation resulted in lethal disease in all mice with comparable time-to-death as unengrafted mice.