Author(s): Barros, Maria Margarida ; Oliveira, Ricardo ; Campos, Ana Maria ; Castro, Joana ; Araújo, Daniela ; Silva, Sónia ; Monteiro, Divanildo Outor ; Almeida, Carina
Date: 2023
Persistent ID: https://hdl.handle.net/1822/83912
Origin: RepositóriUM - Universidade do Minho
The most common bacterial pathogen causing enteric infections in swine is enterotoxigenic Escherichiacoli (ETEC). ETEC-associated diseases, lead to acute diarrhoea and eventual death of the animal, resulting in significant costs to the swine industry [1]. The toxins/fimbriae produced areessentialfor theirpathogenicity. Fimbriae are responsible for the first adhesion of ETEC to the intestinal epithelial cells, giving rise to the onset of infection. In particular, the F4 type (K88) fimbriae are frequently attributed to neonatal infections and most post-weaning diarrhoeal infections [2]. These diseases are traditionally prevented or treated with antibiotics, but antibiotics use is becoming highly restricted due to the emergence of resistant bacteria and its implications to human health [3]. Thus, the development of aptamers (small single-stranded oligonucleotides capable of binding to target molecules with great affinity and specificity [4]) to target the F4-type fimbriae and block the initial ETEC adhesion is an alternative. The present study focuses on the binding and affinity testing of a pre-selected aptamer for ETEC fimbriaagainst the F4-ETEC strain and other bacterial strains (F5, F41-ETEC, F6-ETEC, F18- ETEC, Staphylococcus aureus ATCC 25929, Klebsiella pneumonia ATCC 43216, Escherichia coli K12) by quantitative PCR. Then, we tested the aptamer toxicity in Galleria mellonella by inoculation of different concentrations (1 µM, 10 µM, 20 µM) in comparison to a control solution (PBS). Relatively to the specificity and affinity of the aptamer, preliminary results showed a good affinity to ETEC-fimbria; however, somecross-reactions with other bacterial species with similar fimbriae to those of ETEC was observed. Aptamer did not demonstrate any toxicity in Galleria mellonella after 96h independently of the concentrations of the inoculated aptamer. Further research will be carried on to assess the survival of Galleria mellonella pre-infected with ETEC and subject to aptamer treatment.
