Effects of P. berghei infection on iNOS mRNA expression in mice liver and spleen. Expression of iNOS mRNA in the liver and spleen of DBA-2 (A and B, N = 3) and C57BL/6 (C and D, N = 4) mice infected with P. berghei (ANKA), when parasitaemia rates rose to levels >30%PE (DBA-2) on PID20 or >20%PE (C57BL/6) on PID10 and respective non-infected controls (N = 3). For comparative purposes, levels of iNOS mRNA were also determined in the liver (A, N = 6) and spleen (B, N = 5) of non-infected DBA-2 mice treated with E. coli LPS (5 mg/kg i.p. 12 hours earlier). Column height represents mean ± S.E.M. for relative levels of mRNA. Differences (Mann-Whitney U test, P < 0.05) between infected (malaria) and non-infected control (Ctrl) are indicated by an asterisk (*). Quantification of mRNA was by real time RT-PCR.