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). Here, IL6 is linked to infection.