Figure 1.

Absence of NOS2 confers susceptibility to primary Mtb infection. (a) Survival curves of litter-matched NOS2^−/− (n = 15), wild-type (n = 11), and heterozygous mice (n = 4) mice injected i.v. with 10⁵ CFU of Mtb Erdman bacilli. Data are from two independent experiments. Differences between NOS2^+/+ or NOS2^+/− and NOS2^−/− were statistically significant (P < 0.0001, log-rank test). (b) Genotypic and haplotypic allele-specific PCR strategies. Primer positions (arrows) for murine NOS2 originate within the antisense phosphoglycerate kinase-Neo^r targeted insertion (hatched box) or 5′ untranslated region sequences. Terminal 8-bp template sequences are shown. Sizes of the expected amplificands are in brackets. NRAMP1 primer pairs flank intron 5, with the 3′ polymorphic substitution (nucleotide 596) underlined. (c) NRAMP1 haplotype distribution versus Mtb growth (mean ± SEM) in the lungs (○, •), livers (□, ▪), and spleens (⋄, ♦) of NOS2^+/+ (Bcg^r, n = 7; Bcg^s, n = 3) and NOS2^−/− mice (Bcg^r, n = 9; Bcg, n = 5), respectively. (Inset) PCR amplificands of inherited NRAMP1 variant alleles (r, Bcg^r; s, Bcg^s) and intact or targeted NOS2 alleles (arrows), the latter shown with a NOS2^+/− control.