FIG 4.

Neurovirulence of SFV6, A774wt, and viruses harboring two copies of nsP3. (A) Groups (n = 37) of 4- to 5-week-old mice were inoculated i.p. with the indicated virus (5,000 PFU/mouse) and monitored for survival for 10 days. (B) Groups (n = 7) of 4- to 5-week-old mice were inoculated i.p. with the indicated virus (5,000 PFU/mouse) and monitored for survival for 10 days. (C and D) Virus titers in the blood of infected animals on PID 1 (C) and on PID 3 (D). (E) Virus titers in brain tissue on PID 3. Each symbol represents an individual mouse; the line depicts the mean titer of each group. The dotted line depicts the limit of detection. Statistical significance was determined using the Mann-Whitney test. Only statistically significant differences are indicated: **, P < 0.01; ****, P < 0.0001. (F) Detection of viruses with two copies of nsP3 in brains of mice at the time of the clinical endpoint of the experiment. Total RNA was isolated from brain homogenates, reverse transcribed, and analyzed using PCR. The left panels show schematic representations of PCR products. Obtained PCR products were analyzed on a 1% agarose gel (right panels).