Objective Using Drosophila as a host to compare the gene expression patterns in S2 cells after infection with Listeria monocytogenes, L. grayi, and L. welshimeri, and provide a research basis for exploring the innate immune defense mechanisms of the host and the differential pathogenic mechanisms of different Listeria strains.

Method After infection of L. monocytogenes, L. grayi or L. welshimeri for 3 h, the mRNA expression profiles in Drosophila S2 cells were detected by using transcriptome sequencing technology. Analysis of differentially expressed genes (DEGs) was performed using bioinformatics tools, including GO annotation and KEGG analysis. Finally, the mRNA levels of five antimicrobial peptide genes associated with the Toll and Imd signaling pathway were validated using qPCR technology.

Result After infection of L. monocytogenes, L. gray or L. welshimeri, there were 18 DEGs in common, as well as 104, 28, and 33 unique DEGs respectively in the Drosophila S2 cells. The DEGs commonly existed in three Listeria infected groups were annotated in GO terms including metabolic process, cellular process, cell, organelle, membrane, catalytic activity, response to stimulus, immune system process, transporter activity, and etc. The unique DEGs existed in L. monocytogenes infected group were annotated in GO terms such as biological adhesion, presynaptic process involved in chemical synaptic transmission, negative regulation of biological process, signaling, nucleic acid binding transcription factor activity, signal transducer activity, and nutrient reservoir activity. The unique DEGs in the L. grayi infected group were annotated in GO terms such as multi-organism process and extracellular regions, while the unique DEGs in the L. welshimeri infection group were annotated in GO terms such as developmental processes and membrane-enclosed lumen. The quantitative results of qRT-PCR validation of five antimicrobial peptide genes related to Toll and Imd signaling pathway were consistent with the transcriptomic results.

Conclusion The expression patterns in S2 cells affected by the infection of these three Listeria species exhibited some similarities but also differences. The variation of the signaling pathways may be related to the virulence of these Listeria species in S2 cells.