Oral administration of P. aeruginosa peptidoglycan leads to infection resistance of silkworms against P. aeruginosa.

A. Silkworms were fed a normal diet (n = 30) or a diet containing P. aeruginosa lipopolysaccharides (n = 27) for 2 d and then injected with P. aeruginosa. Results from three independent trials (S2 Table, exp. 1–3) were combined into a single analysis. The combined survival curve is shown in the figure. Survival of silkworms fed the normal diet did not differ significantly from that of silkworms fed the diet containing lipopolysaccharides (p = 0.893). None of the mock-infected silkworms died (S2 Fig). B. Silkworms were fed a normal diet (n = 20) or a diet containing P. aeruginosa peptidoglycans (n = 20) for 2 d, and then injected with P. aeruginosa. Results from two independent trials (S2 Table, exp. 4–5) were combined into a single analysis. The combined survival curve is shown in the figure. The survival of silkworms fed the diet containing P. aeruginosa peptidoglycans was significantly longer than that of silkworms fed the normal diet (p = 1.76E-04). None of the mock-infected silkworms died (S2 Fig). C. Silkworms were administered a normal diet (n = 20), diet containing S. aureus peptidoglycans (n = 20), or diet containing L. plantarum peptidoglycans (n = 20) for 2 d, and then injected with P. aeruginosa. Results from two independent trials (S2 Table, exp. 6–7) were combined into a single analysis. The combined survival curve is shown in the figures. Survival of silkworms fed a diet containing S. aureus or L. plantarum peptidoglycans was significantly longer than that of silkworms fed a normal diet (p = 5.62E-06 or 3.37E-07). None of the mock-infected silkworms died (S2 Fig).