Figure 1: The lung is a key site of immunity to N. brasiliensis reinfection.

(a) Mice were primed by s.c. infection and reinfected 30 days later by either s.c. or i.v. inoculation (dark grey). Naïve mice were infected by either s.c.- or i.v. inoculation (light grey). Lung worm burden was assessed 2 days after challenge. The calculated percentage of protection is indicated on the graph (n=5 mice, mean+s.e.m., representative of three independent experiments, ANOVA). (b) Mice were s.c. infected 4, 9, 20 or 30 days before i.v.- or s.c. reinfection. Lung worm burden was assessed 2 days after challenge and protection was calculated as a percentage (n=5 mice, mean+s.e.m., representative of two independent experiments, ANOVA). (c,d) Number of N. brasiliensis larvae in lung tissue (c) and number of red blood cells in the BALF (d) 2, 24 or 48 h post-primary (open boxes) or secondary (closed circles) i.v. infection (with 30 days between primary and reinfection; n=5 mice, mean+s.e.m., representative of two independent experiments, ANOVA). (e) Haematoxylin and eosin staining of lung sections at 48 h post-primary (Nb) or i.v. reinfection (Nb+Nb) infection. Scale bar, 100 μm. (f) Number of N. brasiliensis larvae in the lung parenchyma (light grey bars) or airway space, measured in BALF (dark grey bars), 2, 24 or 48 h post-primary or i.v. reinfection (n=5 mice, mean+s.e.m., representative of two independent experiments, ANOVA). NS, non-significant; P>0.05; ^▪P<0.07; *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001.