FIG 1.

SFV variants vary in virulence, viremia, and brain titer following i.p. inoculation of adult mice. (A) Schematic representation of the genomes of SFV L10 and used SFV constructs. These viruses (5,000 PFU) were i.p. inoculated into 4- to 5-week-old BALB/c mice. Groups (n = 8) were monitored for survival for up to 2 weeks. Virulence (indicated by + or −) was defined as described in Materials and Methods. Virus titers in groups (n = 6) in the blood (B and C) and brain (D and E) were determined by plaque assay at PID 1 and 3. Each symbol represents an individual mouse. The line depicts the mean titer for each group. The dotted line depicts the limit of detection. Blood and brain virus titers for viruses b to g were compared by Mann-Whitney test to those for SFV4 (a) and SFV6 (c). In panel B, results of viruses c, e, and f were statistically significantly different from those for SFV4. Results for SFV6 also were significantly different from those for viruses b, d, and g. In panel C, titers of viruses b, c, e, and f were statistically significantly different from those for SFV4. SFV6 also was significantly different from d and g. In panel D, results for viruses c, e, and f were statistically significantly different from those for SFV4. SFV6 also was significantly different from b, d and g. In panel E, results for viruses b, c, e, and f were statistically significantly different from those for SFV4. SFV6 also was significantly different from d and g.