The virulence factor ychO has a pleiotropic action in an Avian Pathogenic Escherichia coli (APEC) strain

Abstract

BackgroundAvian pathogenic Escherichia coli strains cause extraintestinal diseases in birds, leading to substantial economic losses to the poultry industry worldwide. Bacteria that invade cells can overcome the host humoral immune response, resulting in a higher pathogenicity potential. Invasins are members of a large family of outer membrane proteins that allow pathogen invasion into host cells by interacting with specific receptors on the cell surface.ResultsAn in silico analysis of the genome of a septicemic APEC strain (SEPT362) demonstrated the presence of a putative invasin homologous to the ychO gene from E. coli str. K-12 substr. MG1655. In vitro and in vivo assays comparing a mutant strain carrying a null mutation of this gene, a complemented strain, and its counterpart wild-type strain showed that ychO plays a role in the pathogenicity of APEC strain SEPT362. In vitro assays demonstrated that the mutant strain exhibited significant decreases in bacterial adhesiveness and invasiveness in chicken cells and biofilm formation. In vivo assay indicated a decrease in pathogenicity of the mutant strain. Moreover, transcriptome analysis demonstrated that the ychO deletion affected the expression of 426 genes. Among the altered genes, 93.66 % were downregulated in the mutant, including membrane proteins and metabolism genes.ConclusionThe results led us to propose that gene ychO contributes to the pathogenicity of APEC strain SEPT362 influencing, in a pleiotropic manner, many biological characteristics, such as adhesion and invasion of in vitro cultured cells, biofilm formation and motility, which could be due to the possible membrane location of this protein. All of these results suggest that the absence of gene ychO would influence the virulence of the APEC strain herein studied.

Avian Pathogenic Escherichia coli (APEC): An Overview of Virulence and Pathogenesis Factors, Zoonotic Potential, and Control Strategies

“…IbeR, a regulator of ibe RAT operon, contributes to invasion, resistance to serum and environmental stresses, and the expression of virulence genes [ 49 ]. Similarly, ych O, a putative invasin gene, plays a role in motility, adhesion, invasion, biofilm formation, and the expression of membrane proteins and metabolism genes [ 50 ].…”

Effects of ESA_00986 Gene on Adhesion/Invasion and Virulence of Cronobacter sakazakii and Its Molecular Mechanism

“…Invasins are proteins that allow bacteria to penetrate cells; they usually adhere to a cell before invading eukaryotic cells and also can help pathogens colonize, maintain, and spread pathogens within the host organism [ 37 ]. Deletion of the invasion gene ychO in avian pathogenic E. coli decreased its ability to adhere to and infect chicken fibroblasts [ 38 ]. In the present study, the results suggest that ESA_00986 plays an important role in adhesion and infection by C. sakazakii and knocking out ESA_00986 can reduce the toxicity of C. sakazakii in vivo, indicating that ESA_00986 encodes an important virulence factor.…”

Novel small molecule modulators of quorum sensing in avian pathogenic Escherichia coli (APEC)

“…In addition, deletion of luxS also resulted in reduced adherence and invasion abilities of APEC O78 and, consequently, its survival in cultured cells [2,5]. Adherence and invasion are important for APEC pathogenesis and mediate colonization, survival and spread in the host [33]. Our results suggest that the selected AI-2 inhibitors, with the exception of C4, might interfere with synthesis, secretion, and/ or transport of AI-2 via their effect on the luxS; affecting QS and cognate pathogenicity of APEC [34].…”