The insect immune system can produce defensive molecules, such as antimicrobial peptides (AMPs), to eliminate invading pathogens. Here, we report the identification of two cDNAs (MseLeb1, MseLeb2) that encode lepidopteral lebocin preproproteins in the oriental armyworm, Mythimna separata. Their open reading frames are 483/492 bp that encode 161/164 aa peptides. MseLeb1 is mainly expressed in the fat body and epidermis, while MseLeb2 is mainly expressed in the fat body, Malpighian tube, and epidermis. They were significantly induced by Escherichia coli, Staphylococcus aureus, and Beauveria bassiana in hemocytes. The preproproteins can be processed after RXXR motifs into mature peptides. Multiple sequence alignment indicates that MseLeb1 (18–42, 121–161) are potentially active peptides. Five peptides were synthesized for analyses: 18–42, 121–161, 121–154, 121–151, 121–146. Synthetic peptides showed agglutinating activity, but no hemolytic activity. Bacterial growth assay, colony formation assay, and electron microscopy revealed that synthetic peptides can inhibit bacterial growth and disrupt bacterial cell wall. B. bassiana conidia and blastospores were lysed by synthetic peptides. These results indicate that MseLeb1 and MseLeb2 are immune responsive lebocins, and the mature peptides have antibacterial and antifungal activities.

昆虫免疫系统可以产生防御分子，例如抗菌肽 (AMP)，以消除入侵的病原体。在这里，我们报告了在东方粘虫Mythimna separata中编码鳞翅目 lebocin 前原蛋白的两种 cDNA（ MseLeb1、MseLeb2 ）的鉴定。它们的开放阅读框为 483/492 bp，编码 161/164 个氨基酸肽。MseLeb1主要在脂肪体和表皮中表达，而MseLeb2主要在脂肪体、马尔皮基管和表皮中表达。大肠埃希菌、金黄色葡萄球菌和白僵菌在血细胞中有显着诱导。可以在 RXXR 基序之后将前原蛋白加工成成熟肽。多序列比对表明 MseLeb1 (18–42, 121–161) 是潜在的活性肽。合成了五种肽用于分析：18-42、121-161、121-154、121-151、121-146。合成肽显示出凝集活性，但没有溶血活性。细菌生长试验、菌落形成试验和电子显微镜显示合成肽可以抑制细菌生长并破坏细菌细胞壁。B. bassiana分生孢子和芽生孢子被合成肽裂解。这些结果表明MseLeb1和MseLeb2是免疫反应性lebocins，成熟肽具有抗菌和抗真菌活性。