Fig. 4.
ICMV immunization sustains antigen deposition in dLNs and induces germinal center (GC) formation. (A and B) C57Bl/6 mice were immunized with 100 μg fluorophore-conjugated OVA (shown in red) either in soluble or ICMV (shown in blue) formulations with 5 μg MPLA, and dLNs excised at indicated time points were examined by immunohistochemical analysis. (A) Representative confocal sections of dLNs; pink signals indicate colocalized OVA/ICMV lipids. Day 14 sections were stained with anti-GL-7 to identify GCs. (B) Enumeration of GCs located within 100 μm of ICMV-draining sites in dLNs. (C–G) C57Bl/6 mice were immunized with 1 μg VMP001 and 0.1 μg MPLA in either soluble or ICMV formulations, and dLNs were analyzed for GC formation on day 14. Shown are representative flow cytometry scatter plots of (C) isotype-switched GC B cells (GL-7+PNA+), gated on B220+IgDlow populations, and (D) their absolute numbers in dLNs. (E) Number of GCs observed in sections from whole dLNs (n = 4), cryosectioned and stained with anti-B220 and anti-GL-7. (F and G) Representative confocal micrographs of dLNs from immunized animals. Scale bars, 200 μm. Data represent the mean ± SEM of two to three independent experiments conducted with n = 2–3.