Deleção dos genes yadC e yicS de uma linhagem SCI-07 de Escherichia coli patogênica para aves (APEC) e suas contribuições para a patogenicidade

Author(s)

Renu Verma

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2016-06-16

Examining board members

Wanderley Dias da Silveira; Marcelo Palma Sircili; Marcelo de Carvalho Ramos; Matheus Aparecido Pereira Cipriano; Jacqueline Boldrin de Paiva

• Advisor: Wanderley Dias da Silveira; Thaís Cabrera Galvão Rojas

Abstract

Brazil is the third largest producer and first exporter of poultry meat worldwide. Avian Pathogenic Escherichia coli (APEC) is responsible for significant economic losses in multi-million dollar in the industry, by causing systemic or localized diseases collectively known as colibacillosis. Besides its importance, the virulence mechanisms of these pathotypes have not been fully elucidated yet. Therefore, in this work, our aim was to study genes, which could be potentially involved in the pathogenicity of an APEC strain isolated from a chicken presenting clinical signs of Swollen Head Syndrome (strain SCI-07; nontypeable O: H31). Two genes yadC and yicS, which were demonstrated under positive selection, were chosen to be deleted and their contribution to several phenotypes related to pathogenesis process were further evaluated. For this, the mutated and complemented strains were compared to the wild type strain in several tests, such as mortality, motility, survival in macrophage, adhesion and invasion assays. The mutant yadC showed a decreased adhesion capacity in human epithelial (HeLa cells) and reduced ability in invasion to epithelial cells (Hep-2 cells) as well as decreased capacity of survival in avian macrophages (HD11 cells). The mutant also reduced mortality levels, as well as a reduced ability in the systemic animal infection experiment. The mutant yicS showed a decreased invasion level in CEC-32 cells and Hep-2 cell, reduced motility and a lower capacity of biofilm formation. This mutant also presented a decrease in mortality in one-day old-chicks model and systemic infection experiments. Taken together, these results indicate that these genes contribute to the infectious process and are important for the pathogenicity of strain SCI-07 (AU)

• FAPESP's process: 12/23289-3 - Deletion of putative invasin and DnaK genes from avian pathogenic Escherichia coli (APEC) strain SCI07 to study their role in pathogenicity and obtain attenuated vaccine strains
• Grantee: Renu Verma
• Support Opportunities: Scholarships in Brazil - Doctorate