Mice and LCMV infection

C57BL/6 (B6) mice were purchased from Charles River Laboratories (Germany). BAC-transgenic C57BL/6N-Tg (Ccl19-Cre)489Biat (Ccl19-Cre) mice (36) and R26R-EYFP reporter mice (38) have been previously described. To specifically ablate Ifnar expression in FRCs, Ccl19-Cre mice were crossed with Ifnar^fl/fl mice (provided by U. Kalinke, Helmholtz Center for Infection Research, Hannover, Germany) (37). All mice were on the C57BL/6 genetic background and were maintained in individually ventilated cages and were used between 8 and 10 weeks of age. Experiments were performed in accordance with federal and cantonal guidelines (Tierschutzgesetz) under permission numbers SG12/16, SG14/18, and SG05/17 after review and approval by the Cantonal Veterinary Office (St. Gallen, Switzerland). Mice were subcutaneously infected in one flank with 200 focus-forming units (ffu) of LCMV Armstrong, and analyses were performed at the indicated time points. LCMV titration was performed using permissive MC57 cell lines as previously described (40, 61, 62).