FIG. 6.
Early splenic LCMV production after low-dose infection i.v. with 5 × 102 PFU of LCMV-WE depends on an intact splenic architecture but not on IgM in serum. (A) Four mice of each indicated strain were infected with 500 PFU of LCMV i.v., and the LCMV-WE titers in the indicated organs from individual mice are shown. LCMV detection limits for each organ are indicated as dotted lines. (B) Spleen sections from an IgM−/− C57BL/6 mouse (with no serum IgM but all other Ig classes) (left) and a μMT mouse (no serum Ig) at 4 days postinfection, immunostained for MAdCAM-1 (positive reaction in red) and hybridized in situ with 35S-labeled RNA probes specific for LCMV GP. Magnification, ×250.