Immunity is dependent on cognate B cells and partially transferrable by antibody.

<p><b>A</b>. Gated CD19⁺ MLN cell expression of cell surface IgM and IgG1 in naïve and d 7 and d 14 post-challenge PBS and HES B6 mice. <b>B</b>. Gated CD19⁺ MLN cell expression of cell surface CD21/CD35 (CR2/CR1) and CD23 (FcεRII) in naïve and d 7 post-challenge PBS and HES B6 mice. Numbers represent geoMFI of CD23 (blue) and CD21/CD35 (red) expression. A-B representative of two independent experiments with 3–5 mice per group. <b>C</b>. Pre-challenge anti-HES IgM, IgG1, IgG2c, IgA and IgE titers in PBS and HES vaccinated B6 mice with 5 mice per group. <b>D</b>. Day 28 post-challenge worm burdens from C57BL/6 and μMT mice following HES immunization or PBS control. Data pooled from two experiments. Significance determined by ANOVA as indicated. <b>E, F</b>. Day 28 post-challenge worm and fecal egg burdens (d 14, 21, 28) in naïve C57BL/6 mice receiving IgG from vaccinated or primary infected mice, or PBS, as detailed in materials and methods. Data are pooled from two experiments, with significance determined by ANOVA <i>Vs</i> C57BL/6 PBS. <b>G</b>. Day 21 post-challenge adult worm burdens in C57BL/6 and FcRγ^–/–x C3^–/– mice following HES immunization or PBS control. Significance determined by <i>t</i>-test as indicated. See also <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004676#ppat.1004676.s002" target="_blank">S2 Fig</a>.