Fig. 1. Anti-Lm antibodies acquire protective function during pregnancy.

(a-c) Anti-Lm IgG titers (a), survival (b) and bacterial burdens (c) in neonatal mice infected with virulent Lm born to WT, μMT−/− or CD8−/− female mice primed with attenuated ΔActA Lm one week prior to mating or naive WT control mice without preconceptual priming. (d) Bacterial burden in neonatal mice infected with virulent Lm born to WT female mice primed with ΔActA Lm or virulent Lm 3 weeks prior to mating. (e) Bacterial burden 3 days after secondary challenge of ΔActA Lm-primed virgin female CD8−/− adult mice or preconceptually ΔActA Lm-primed CD8−/− female mice 3 weeks post-partum. (f) Bacterial burden after virulent Lm infection in neonatal mice transferred sera from ΔActA Lm-primed virgin (vSera) or pregnant mice in late gestation through early postpartum (pSera). (g) Bacterial burden after virulent Lm infection in neonatal mice transferred sera from preconceptual ΔActA Lm-primed mice harvested during the indicated pregnancy or postpartum time points. (h) Bacterial burden after virulent Lm infection in neonatal mice cross-fostered within 12 hours after birth by naive or ΔActA Lm-primed dams. (i) Bacterial burden after virulent Lm infection in neonatal mice nursed by WT, μMT−/−, or FcRγ−/− mice administered vSera on the day of delivery and 3 days later. Pups were infected with virulent Lm 3-4 days after birth, with enumeration of bacterial burden 72 hours post-infection. Each symbol represents an individual mouse, with graphs showing data combined from at least 2 independent experiments each with 3-5 mice per group per experiment. Bar, mean ± standard error. P values between key groups are shown as determined by one-way ANOVA adjusting for multiple comparisons (a, c, d, f, g, h, i), unpaired t-test (e), or Log-rank (Mantel-Cox) test (b). Dotted lines, limit of detection.