Uncovering the cellular and humoral immune responses of Antheraea pernyi hemolymph to Antheraea pernyi nucleopolyhedrovirus infection by transcriptome analysis.

Insects have evolved efficient innate immune systems to defend themselves against the invasion of pathogens and parasites. We infected the lepidopteran Antheraea pernyi with Antheraea pernyi nucleopolyhedrovirus (ApNPV) and studied the host's transcriptional response to unravel the cellular and humoral immune responses of A. pernyi larval hemolymph to ApNPV. Comparison of gene expression levels revealed that a total of 3191 genes were differentially expressed, including 1107 up-regulated and 2084 down-regulated genes in ApNPV-infected hemolymph. Of these, 1416 and 982 differentially expressed genes (DEGs) were enriched in 3253 Gene Ontology terms and 258 KEGG pathways, respectively. DEGs involved in immunity related pathways were selected for further analysis. We screened 184 and 63 DEGs involved in cellular and humoral immune-related pathways, respectively, via KEGG analysis. Among the cellular immune-related pathways, autophagy, endocytosis, and lysosome were activated based on the expression profiles of several key regulatory genes, such as the up-regulation of Atg3 and LPS-induced TN factor, and the down-regulation of PIK3R4, HSC70 and V-ATPase. We concluded that phagosome, apoptosis, and ubiquitin-mediated proteolysis were suppressed by ApNPV as a result of down-regulation of most related DEGs. The majority of the DEGs enriched in Toll, Jak-STAT, MAPK, NF-κB and Insulin signaling pathways, complement and coagulation cascades, and melanogenesis were down-regulated, demonstrating that ApNPV infection greatly inhibited humoral immunity in the hemolymph of A. pernyi larvae. Our findings may serve as a basis for further research on the antiviral molecular mechanisms of A. pernyi.