Impact of prior N. brasiliensis exposure on the expression of Th1-associated cytokine genes in the lungs during P. berghei infection. Real-time RT-PCR analysis of mRNA levels of ifng, tnf, il12p35, il12p40, il18, nos2, il1b, and il6 in the lungs isolated from mice infected with P. berghei alone (Pb), N. brasiliensis alone (Nb), or with hookworm 13 days prior to malaria (Nb/Pb) at 0, 3, 5, and 8 days after the initiation of malaria infection. Data points are mean fold change in transcription over that of naive Day 0 mice normalized to GAPDH ± SEM, N = 5 wild-type BALB/cJ male mice. ** = p <0.01 by two-way ANOVA comparing Nb/Pb to Pb.