B cell proliferation and IgG production. The frequency of proliferating in MZ-like and memory B cell subsets was measured using flow cytometry based on the expression of Ki67 in (A) BAL and (B) PBMC. SVV-specific (C) IgG antibody endpoint titers were measured by standard ELISA. SVV BAC (open circle) and WT SVV (closed circle). Average ± SEM *p<0.05.