MyD88-deficient mice have a delayed IgM response to B. hermsii lipoproteins. Antibodies against lipoprotein-enriched n-butanol extract of B. hermsii were analyzed each day of infection, day 1 through day 6. Each panel shows reactivity of sera collected from one wild-type and one MyD88−/− mouse, for a total of five mice for each genotype. Arrows denote reactivity to an ∼17-kDa lipoprotein. Uninf., uninfected; KO, knockout; post-inf., postinfection.