FIG 1.

Loss of SHP1 expression in B cells leads to attenuated establishment of MHV68 chronic infection. CD19 Cre-negative or CD19 Cre-positive mice were intranasally infected with 500 PFU of MHV68, and splenocytes were harvested at 16 days postinfection. As described in Materials and Methods, limiting dilution assays were used to measure the frequency (A) and, subsequently, the absolute number (B) of MHV68 genome-positive splenocytes and the frequency of viral reactivation (C). Splenocytes from 3 to 5 mice were pooled within an individual group in each experiment, and data from at least 3 independent experiments were pooled. Error bars here and throughout the figures represent the standard error of the measurement. The dashed lines in panels A and C are drawn at 63% to define the frequency of a positive event. CPE, cytopathic effect.