Figure 3. The 40 bp internal repeat is important for virus-induced splenomegaly and for ex vivo reactivation of latently infected splenocytes.

C57BL/6 mice were i.n. infected with 5×10⁴ PFU. A) Extent of splenomegaly. At the indicated time points after infection, spleens were harvested and the spleen weight was determined. Shown are means±SD of the number of mice indicated in brackets. The asterisks indicate a statistically significant difference (p = 0.043 at day 13 and p = 1.02×10⁻⁸ at day 17; Student's t-test). The extent of ex vivo reactivation was determined 10 (B), 13 (C), 17 (D) and 23 (E) days after infection. Data shown are from a representative experiment with splenocytes pooled from 3 mice per group. F) Summary of independent ex vivo reactivation experiments performed with splenocytes at day 17 after infection. In each individual experiment, splenocytes from 3 mice per group were pooled. Shown are the reciprocal frequencies of reactivation (mean±SD; n = 4 for parental virus and Delta 40 bp mutant, n = 2 for revertant), calculated as described in materials and methods. The asterisk indicates a statistically significant difference (p = 0.040; Student's t-test).