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Keywords:

  • insect immunity;
  • Bombyx mori;
  • antimicrobial peptide gene;
  • lipopolysaccharide

Abstract

Lipopolysaccharide (LPS), a major cell wall component of Gram-negative bacteria, was found to be unable to activate immune-related genes in Drosophila melanogaster. In contrast, highly purified LPS elicited immune-related gene expression in the fat body of Bombyx mori. However, the level of activation by highly purified LPS was lower than crude LPS and peptidoglycan. Furthermore, synthetic lipid A also activated these genes, suggesting that B. mori possesses unknown signal pathways to activate immune-related genes by LPS. Up-regulation of antimicrobial peptide genes by highly purified LPS was not confirmed in the immune-responsive cell line, NIAS-Bm-aff3, suggesting that some factors necessary for signal transduction activated by LPS are deficient in this cell line.