Fig. 4.

r3LCMVs are displaced by 2-segment viruses and require mutations from a persistent variant of LCMV, clone 13, to persist in IFNAR1^−/− mice. (A) Three-segment LCMV requires the glycoprotein (GP) and polymerase (L) substitutions of clone 13 to persist in IFNAR1^−/− animals. IFNAR1^−/− mice were inoculated with the indicated tripartite virus bearing the GP and L amino acid variants from the acute LCMV Armstrong53b strain or the persistent LCMV clone 13 strain (as described by Sullivan et al. [21]). Mice were bled at the indicated time points postinfection to assess for viremia. Means ± SEM are shown for 7 animals per group as indicated prior to termination of the time course at 96 dpi. (B) Tripartite LCMV does not persist in the presence of bisegmented LCMV. IFNAR1^−/− mice were infected with 2 × 10⁷ FFU of gfpIL10 i.v. At 9 days postinfection, mice were challenged with 2 × 10⁵ PFU bisegmented LCMV clone 13 i.v. and subsequently bled at 2 days postchallenge to quantitate viremia in bisegmented virus versus that in trisegmented virus. Similar results were observed with both r3LCMV gfpGFP and r3LCMV gfpIL10. Means ± SEM are shown for 4 mice. Results for 1 of 2 similar experiments are shown.