Within infected SGs, CD200+ cells were predominantly large CD31+ cells (Fig. 2A, isotype controls:S1A Fig.) that were EpCAM- (Fig. 2B), suggestive of endothelial cell origin, and not EpCAM+ acinar epithelial cells in which MCMV replicates during the persistent phase of infection [33]. This evidence concerns the gene PECAM1 and infection.