The study of influence of stresses on virulence genes expression in foodborne pathogens Сampylobacter jejuni

• Natalya R. Efimochkina
• Bykova Irina B.
• Yulia M. Markova
• Korotkevich Yu.V.
• Svetlana A. Sheveleva

Abstract

The study of the responses to cold exposure in Campylobacter jejuni (C. jejuni) – one of the most common foodborne pathogens is important for elucidating the mechanisms of acquisition of products contaminated with campylobacter, hazardous properties. These data are also necessary to create effective systems of microbiological controls at all stages of production and storage of food. 5 pairs of oligonucleotide primers were selected for detecting of genes cadF, cdtB, ciaB, flaA, iamA, encoding the main factors of pathogenicity of foodborne pathogens Сampylobacter jejuni – adhesion and invasion of epithelial cells, production of CDT-toxin and mobility. To quantify the expression levels of target genes of C. jejuni a comparative method of determining the amount of amplification products of genes encoding pathogenicity factors of Campylobacter spp. has been developed using real-time PCR with intercalating dyes. To calculate and quantify gene expression the mathematical models have been obtained that allow extrapolation of threshold cycles of amplification to the initial number of copies of RNA/DNA in the tested samples. It has been established that exposure of C. jejuni at low temperatures +4 °C did not lead to increased levels of expression of genes cdtB and сiaB. However, in the populations of C. jejuni subjected to freezing, followed by incubation at optimum for the pathogen temperature of +42 °C, the increase in expression of mRNA encoding protein subunit B of CDT-toxin and antigenic marker of invasion took place. The number of copies of RNA in C. jejuni after stress exposure increased by 1.14–2.6 lg in comparison with intact cultures. CdtB and сiaB gene expression in C. jejuni can serve as an indicator of cell response to stress and helps to restore the functions of the bacterial cells after the termination of cold exposure and return of the pathogen in conditions favourable to the realization of its pathogenic potential.

Keywords:Сampylobacter jejuni, stresses, virulence factors, gene expression, tolerance, reverse transcription quantitative Rti-PCR

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