The innate immune system of insects is the front line of self-defense against pathogen invasion. Peptidoglycan recognition proteins (PGRPs) are important components and play key roles in insect immune systems by recognizing peptidoglycan (PGN) in bacterial cell walls. We characterized two isoforms of the PGRP-LC gene, BdPGRP-LCa and BdPGRP-LCb, from Bactrocera dorsalis (Hendel), an important fruit and vegetable pest worldwide. These two isoforms contain an open reading frames of 1 668 bp and 1 731 bp, encoding a protein of 555 and 576 amino acids, respectively. Quantitative real-time PCR results showed that both transcripts were prominently expressed in midgut and fat body of B. dorsalis adult. Inoculation of pathogens showed that both isoforms actively responded to Escherichia coli PGN. We also observed a light response to Staphylococcus aureus PGN. Upon Beauveria bassiana inoculation, the expression of BdPGRP-LCa was enhanced, but the expression of BdPGRP-LCb was suppressed. Suppression of both transcripts by RNA interference led to increased mortality of flies challenged by E. coli, indicating that the two isoforms are involved in sensing Gram-negative bacterial infections.

昆虫的固有免疫系统是抵御病原体入侵的自卫前沿。肽聚糖识别蛋白（PGRP）是重要的组成部分，通过识别细菌细胞壁中的肽聚糖（PGN）在昆虫免疫系统中起关键作用。我们表征了PGRP-LC基因的两个同工型，BdPGRP-LCa和BdPGRP-LCb，来自世界上重​​要的水果和蔬菜害虫Bactrocera dorsalis（Hendel）。这两个同工型包含一个1668 bp和1 731 bp的开放阅读框，分别编码555和576个氨基酸的蛋白质。实时定量PCR结果显示，两个转录本均在背侧双歧杆菌的中肠和脂肪体中显着表达。成人。病原体的接种显示两种同工型均对大肠杆菌PGN产生积极反应。我们还观察到对金黄色葡萄球菌PGN的光反应。一旦白僵菌接种，表达BdPGRP-LCA增强，但表达BdPGRP-LCB被抑制。RNA干扰抑制两种转录本均导致大肠杆菌攻击的果蝇死亡率增加，表明这两种同工型参与了革兰氏阴性细菌感染的检测。