Measurement of pro-inflammatory cytokine expression in spleen of STAT-1-/- mice infected with MOPV revealed upregulation of IL-6 and IL-1β at early stages of the infection and rapidly declined at later time points while TNF-α was downregulated for all viruses except the early stages of MOPV and the late stage of ML29P50 (Figure 5, Appendix A, Figure A3). This evidence concerns the gene IL1B and infection.