IRF1 and infection: After three hours of infection, with IFNγ stimulation for the last two hours, cells pre-infected with either RH(I), Pru(II), or CEP(III) all had significantly lower levels of IRF1 in their nuclei than uninfected cells (Fig. 1A, B), as was previously seen for type I, II, and III strains [8], [9], [13].