Antimicrobial components of haemolymph and exosecretion of larvae Lucilia sericata (Meigen) (Diptera, Calliphoridae)
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- Kruglikova, A.A. J Evol Biochem Phys (2011) 47: 534. doi:10.1134/S0022093011060044
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The present study deals with molecular nature and peculiarities of the functioning of two main protective systems of larvae Lucilia sericata—the antimicrobial compounds of haemolymph and exosecretion released by feeding larvae into environment. In the haemolymph of larvae undergone to bacterial infestation, the chromato-masspectrometry methods identified a set of inducible antibacterial peptides including defensins (3844, 4062, and 4117 Da), P-peptide (3043 Da), and four new polypeptides (3235, 3702, 3746, and 3768 Da). The exosecretion of Lucilia sericata maggots contains the peptides analogous or identical to the haemolymph antimicrobial peptides (diptericins: 8882 Da and 9025 Da), high molecular compounds of the peptide nature (6466 Da, 6633 Da, 5772 Da, 8631 Da, etc.) differing from the known haemolymph components, and the low molecular compounds (130–700 Da). The spectrum of exosecretion bactericidal activity includes the representatives of various groups of bacteria including pathogen the most actual from the medical point of view-the methicillin-resistant Staphylococcus aureus that does not have anti-staphylococcal activity in contrast to haemolymph. The exosecretion components suppressing growth and development of this staphylococcus represent the substances of low molecular mass (from 160 to 1020 Da). The performed studies characterize the strategies used by “surgical maggots” for protection from pathogens and for suppression of microbial competitors, and allow better understanding of molecular mechanisms of larval therapy of purulent infectious diseases. These studies in perspective can serve the basis for creation of the principally new drugs for struggle with usual and antibiotics-resistant bacterial infections.