SDC1 and infection: To confirm that the majority of tdTomato+ CD138+ ASC were indeed virus specific, we directly compared the frequencies of CD138+ tdTomato+ B cells obtained by flow cytometry to virus-specific ELISPOT analyses in CLN and brains at day 14 p.i. (Fig. 1E), when virus-specific ASC peak in CLN and emerge within the CNS following MHV-JHMv2.2-1 infection (4, 14, 32).