IFIT3 and infection: To investigate the effect of exogenous 4-1BB stimulation in the disease outcome, Py-infected WT mice were treated with either an agonistic antibody to 4-1BB (3H3) or isotype control (recombinant immunoglobulin G [rIgG]) on 5 and 7 days post infection (dpi) (Figure 1A), and kinetics of parasite load were monitored.