Abstract: 【Aim】 The objective of this study is to elucidate the roles of peptidoglycan recognition protein LC (PGRP-LC) in response to bacterial infection in Aedes aegypti. 【Methods】 The mRNA abundance of genes of antimicrobial peptides (AMPs) in mosquitoes at different time after infection of Enterobacter cloacae was measured by quantitative real-time PCR (qPCR). After interference of PGRP-LC by RNA interference (RNAi), the expression profiles of immune-related genes were detected by qPCR. The recombinant protein AaPGRP-LC was expressed by prokaryotic expression system and purified through a Ni²⁺-NTA agarose column. The quality of the purified recombinant protein was tested by Western blotting. 【Results】 Gram-negative E. cloacae bacteria could activate the expression of genes of AMPs in Ae. aegypti at 6 h post infection. After depletion of AaPGRP-LC, the transcription levels of genes of AMPs were significantly decreased during bacterial infection. The expression levels of immune-related genes involved in Toll and IMD pathways were down-regulated after interference of AaPGRP-LC. Western blotting of the purified recombinant protein AaPGRP-LC showed a clear and unique target band. 【Conclusion】 AaPGRP-LC modulates the transcriptional expression of genes of many essential AMPs and plays an important regulatory role in response to bacterial infection. It is involved in the regulation of IMD pathway and may also regulate the Toll pathway. The obtained recombinant AaPGRP-LC can be used in the follow-up study.

Key words: Aedes aegypti; innate immunity, bacteria, peptidoglycan recognition proteins, antimicrobial peptides