SDC1 and infection: During infection with a gliatropic mouse hepatitis virus (MHV) derived from the JHM strain (JHMv2.2-1), IgD-positive (IgD+) (naive/transitional) B cells prevail early, but they decrease coincident with increasing proportions of CD138+ antibody (Ab)-secreting cells (ASC) and CD138− IgG+ isotype-switched memory B cells (Bmem) as germinal centers (GCs) are formed in draining lymph nodes (1, 2).