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New Antimicrobial Peptides of Triatoma infestans Hemolymph

Diniz LCL, Silva Junior PI

Laboratório Especial de Toxinologia Aplicada CeTICS, Instituto Butantan, Brasil

Introduction: Triatomine bugs (Hemiptera, Reduviidae), are blood-sucking ectoparasites arthropods of great social, economic and medical relevance. These insects are exposed to a wide variety of pathogens and attempting to survive, they developed important defense mechanisms, mainly their innate immune response. On the liquid fraction of the innate immunity, they produce antimicrobial peptides (AMPs). These molecules represent a major form of insect defense. Despite the new researchs, descriptions of these AMPs are still very limited in triatomines.  Objectives: The objective of this study was to evaluate and identify the presence of AMPs in the hemolymph of Triatoma infestans, triatomine of great importance in the transmission of Chagas disease. Methods: The hemolymph of 17 induced triatomines was collected, subjected to acid extraction, purification, and elution with different concentrations of acetonitrile. Subsequently, the fractions were separated in the HPLC and each peak was tested for growth inhibition of Gram-positive (Microccocus luteus, strain A270) and Gram-negative bacteria (Escherichia coli, strain SBS363) and yeast (Candida parapsilosis, strain IOC 4564). Samples that showed inhibitory activity were submitted to a hemolytic assay to verify their toxicity. Those same samples were processed in the mass spectrometer and analyzed using the software Fingerprint, Blast and databases research. Results and Discussion: Nine molecules showed antimicrobial activity, of which only one showed a hemolytical potential. Of those molecules, one showed similarity with the human fibrinopeptide A. In insects, the closest molecules related to fibrinogen are the Fibrinogen-Related Proteins, which do not have similarity to the fibrinopeptide A from humans. As already described in the tick Boophilus microplus, it may sugest a new mechanism of internalization of this peptide by the insect. In conclusion, taken all our data together, we expect to achieve a better characterization of a new pathway of the immune system of this insect. 

Supported by CNPq, FAPESP

6 - BIOTECHNOLOGY 21th Annual Scientific Meeting of Instituto Butantan.