Análise da atividade antimicrobiana e sinérgica de peptídeos encriptados contra cepas de Staphylococcus aureus e Klebsiella sp, isolados de mastite bovina

• Ano de defesa: 2022
• Autor(a) principal: Silverio, Tatiana Rusch
• Orientador(a): Ramada, Marcelo Henrique Soller
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Católica de Brasília
• Programa de Pós-Graduação: Programa Stricto Sensu em Ciências Genômicas e Biotecnologia
• Departamento: Escola de Saúde e Medicina
• País: Brasil
• Palavras-chave em Português: Mastite bovina; Peptídeos encriptados; Staphylococcus aureus; Peptídeos antimicrobianos
• Palavras-chave em Inglês: Antimicrobial peptides; Encrypted peptides; Bovine mastitis
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS
• Link de acesso: https://bdtd.ucb.br:8443/jspui/handle/tede/2954

The association of resistant strains and the presence of residues in milk are major concerns during bovine mastitis treatment. Therefore, the search for prophylactic and alternative treatment measures that are effective in controlling this pathology’s pathogens is important. Antimicrobial peptides (AMPs) are a promising therapeutic alternative to this problem as they can exert antimicrobial activity in different ways than commercial antibiotics. AMPs are produced by virtually any living organism and can also be found within protein sequences, being classified as intragenic or encrypted peptides (IAPs). Some of these molecules can also act synergistically when combined with antibiotics reducing the effective dosages of both molecules, a desirable trait as antibiotic residue and toxicity are other problems related to bovine mastitis treatments. Therefore, this study aimed to evaluate the minimum inhibitory concentration (MIC) of seven IAPs predicted from the genome of Staphylococcus aureus and Klebsiella pneumoniae, as well as their combinations with the antibiotic gentamicin or ciprofloxacin against S. aureus and Klebsiella sp. bovine mastitis isolates. The IAPs Sa3, Sa6, Kp3, and Pa3 showed antimicrobial activity against the strain 91 of Klebsiella sp., at concentrations of 128 μM, 128 μM, 64 μM and 128 μM, respectively, while Sa7 showed activity only against S. aureus strains at 64 μM in all strains. Based on the MIC values, five IAPs (Sa3, Sa6, Sa7, Kp3, and Pa3) and the antibiotics were selected to proceed with the combination tests through the checkerboard assay. Of the nine tested combinations, eight showed synergistic activity with both antibiotics, except for Pa3 which displayed additive activity when combined with gentamicin. In addition to the MIC and combinations tests, IAPs secondary structure prediction by molecular modeling was performed, as well as an analysis of the stability of these structures in an aqueous environment by molecular dynamics in 100 ns. The results suggest that IAPs have a greater propensity for helical conformation, and their structures remain stable even in an aqueous environment. The results herein indicate that IAPs are interesting candidates for developing joint therapies for bovine mastitis, which should be further studied to validate this possibility.