Hematoxylin and eosin-(H&E) stained lung tissue from mice primed with PBS + BSA (A., B., and C.) or L. plantarum in PBS + BSA (D., E., and F.) prior to virus infection; shown here at day 7 as per Fig. 1A. A. and B. Diffuse alveolar, bronchiolar, and perivascular inflammation is observed in lung tissue from PVM-infected, control-primed mice (original magnifications, 5X, and 10X, respectively). C. Arrows indicate infiltrating granulocytes (original magnification, 40X) seen exiting from the blood vessel in the center of the field in panel B. D. and E. Lung tissue from L. plantarum-primed, PVM-infected mice exhibits diminished alveolar inflammation and pronounced peribronchiolar and perivascular cuffing (original magnifications, 5X and 10X, respectively). F. Enlarged from E. (at arrow) dense lymphocyte-enriched inflammatory infiltrate, consistent with descriptions of induced bronchus-associated lymphoid tissue (iBALT; original magnification, 40X.)