Fig. 1

Early M. leprae-Macrophage Interactions Are Typical of Other Mycobacterial Infections

(A) Diagram of larva 2 days post-fertilization (dpf) with injection sites indicated.

(B) Representative confocal image of an early aggregate of fluorescent macrophages (dashed line) adjacent to the yolk sac in a 6 dpf mpeg1:Brainbow larva at 4 days post-infection (dpi) with ∼10⁴ fluorescent M. leprae. Scale bar, 10 μm.

(C) Mean number of neutrophils recruited to the hindbrain ventricle after injection of ∼100 colony-forming units (CFUs) of P. aeruginosa (Pa), M. marinum, or M. leprae in a 2 dpf larva at 4 hr post-infection; ^∗p < 0.05; ^∗∗p < 0.01; ^∗∗∗p < 0.001 (one-way ANOVA with Bonferroni’s post-test).

(D) Mean number of macrophages recruited to M. marinum (Mm) or M. leprae (Mlep) injection, like in (C), in wild-type (ctrl) animals or those made deficient in CCR2 or MyD88 by morpholino (MO) injection; ^∗∗∗p < 0.001, ^∗∗∗∗p ≤ 0.0001 (one-way ANOVA with Bonferroni’s post-test).

(E) Representative fluorescent images of 2 dpi (4 dpf) WT or macrophage-deficient pu.1 morphant larvae, infected with fluorescent M. leprae like in (B); the arrow indicates the injection site. Scale bar, 100 μm.

(F) Mean bacterial burden of larvae in (E); unpaired Student’s t test.

(G) Representative confocal image of the fluorescent vasculature of a 2 dpi (4 dpf) kdrl:dsRed larva infected with fluorescent M. leprae; bacteria reside within macrophages, apparent by Nomarski microscopy (Figure S1). The arrow indicates M. leprae retained within vessels; arrowheads indicate M. leprae outside of vessels; ISV, intersegmental vessel; asterisk, M. leprae-infected macrophage surrounding the abluminal surface of the vessel.

(H) Proportion of larvae in (G) with M. leprae disseminated outside or contained within the vasculature, 4 days after caudal vein infection, in larvae depleted of macrophages, or not, by clondronate injection (Fisher’s exact test). n = number of larvae per group; all data representative of at least three separate experiments.

See also Figure S1.