Figure 1.

Nearly all “survivor” mice in the 0.2 TCID₅₀ challenge group were not infected with Rift Valley fever virus (RVFV). (A) Survival curve of five inbred mouse strains infected via footpad injection with wild-type RVFV at a dose of 0.2 TCID₅₀ shows “survivor” mice across all five strains. Each line represents the percent survival after infection of five female and five male mice. (B) Enzyme-linked immunosorbent assay (ELISA) and qRT-PCR analysis of “survivor” mice as well as early and late-death 0.2 TCID₅₀-challenged mice as controls. Endpoint RVFV-specific ELISA titer in the serum of mice that survived to day 28 post-infection. Viral load per milligram of tissue in the liver, spleen, brain, and testes of mice that survived to day 28 post-infection was measured by qRT-PCR. The limits of detection for these assays are indicated by dashed lines (ELISA limits of detection due to limited dilutions: lower limit of 100 and upper limit of 12,800; qRT-PCR limit of detection: 77.5 RNA copies/mg).