Selective inhibition of cecropin-like activity of insect immune blood by protease from American foulbrood scales.
Bioassays of American foulbrood larval scale filtrates have shown the presence of an immune inhibitor with a specific activity of proteases that selectively destroy cecropin-like activity in insect immune hemolymphs. It was an unexpected phenomenon to find that Bacillus larvae protease(s), even at trace concentrations, totally inhibits bactericidal activity of immune blood against Escherichia coli D 31. Thermal inactivation of a proteolytic enzyme coincides strictly with a disappearance of the ability to inhibit a cecropin-type activity in an assay system used, although the immune inhibitor was unaffected by trypsin digestion. Since neither bee larval hemolymph nor larval body homogenates possess demonstrable inhibitory action against cecropins present in hemolymph of Celerio euphorbiae and other insects, one can suggest that B. larvae proteases selectively destroy some molecules of the insect humoral immune system. The absence of cecropins in blood of immunized honeybee, Apis mellifera, larvae and a simultaneous high inhibitory activity of B. larvae protease(s) need further study on their role in pathogenesis of American foulbrood of the honeybee.
Jarosz
J
J
Unit of Insect Pathology, M. Curie-Skłodowska University, Lublin, Poland.
Gliński
Z
Z
D000818:Animals; D001407:Bacillus / Q000201:enzymology / Q000472:pathogenicity; D001516:Bees; D010450:Endopeptidases / Q000494:pharmacology*; D006458:Hemolymph / Q000187:drug effects / Q000276:immunology; D007301:Insect Hormones / Q000037:antagonists & inhibitors*; D009036:Moths / Q000276:immunology
D007301:Insect Hormones; D010450:Endopeptidases