FIG 6.

B cell-intrinsic IRF-1 function is dispensable for long-term gammaherpesvirus infection. (A to C) CD19 Cre-positive and Cre-negative littermates were infected as described for Fig. 2. Spleens were collected at 42 days postinfection, processed into a single-cell suspension, and subjected to limiting dilution assays to determine the frequency (A) or absolute number (B) of MHV68 DNA-positive cells and the frequency of ex vivo viral reactivation (C). (D to I) The germinal center response was measured, with germinal center B cells (D to F) defined as B220⁺ GL7⁺ CD95⁺ cells and T follicular helper cells (G to I) defined as CD3⁺ CD4⁺ CXCR5⁺ PD-1⁺ cells. Frequencies of cells, absolute numbers of cells, and reactivation frequencies were determined for panels D and G, E and H, and F and I as described for panels A, B, and C, respectively. Each experimental group consisted of 3 to 4 animals; data were pooled from 2 to 3 independent experiments; standard errors of the means are displayed.