A fast immune priming that confers a complete infection resistance on silkworm (Bombyx mori)

I have previously reported an immune priming in silkworm triggered by peptidoglycans, which is long-lasting but slow-acting. Here I report a faster immune priming, which can be triggered by an injection of gelatin or collagen, that confers a complete infection resistance to Gram-negative bacteria on silkworms. Gelatin-injected silkworms showed 100% viability in a lethal dose of a Gram-negative bacterial infection within two hours after the gelatin injection. Injection of collagen showed a similar effect. Whereas, an injection of non-gelatin protein (bovine serum albumin) solution did not induce such reaction. These results suggest that the silkworm possesses a fast and gelatin-inducible pathway that confers infection resistance to Gram-negative bacteria, which may act as a front-line defense. This finding highlights the potency of gelatin as a tool for investigating the primed immune responses in insect species.