How pathogen genome differences affect public health

Diversity of transducer-like proteins (Tlps) in Campylobacter. Clark C*, Berry C*, Demczuk W*. PLoS One 2019 Mar 25;14(3):e0214228. doi: https://doi.org/10.1371/journal.pone.0214228


This science story looks at innovative work in providing new information on Campylobacter, a common food- and water-borne infectious bacteria affecting Canadians and the global public health community. The research highlights one of many activities underway at the NML to improve understanding of infectious bacteria and help efforts to identify, investigate, control and prevent infectious disease.

What was known about this area prior to your work, and why was the research done?

The World Health Organization recognizes Campylobacter as the most common bacterial cause of diarrheal disease in the world. Campylobacter is often introduced into human populations through consumption of contaminated food or water. This bacteria is continually evolving to adapt to the host and environment, increasing its ability to infect. Certain bacterial cell membrane receptors, known as transducer-like proteins (Tlps), play an important role in Campylobacter infections. Previous studies have shown that small molecules like sugars, amino acids, metal ions, and bile salts bind to Tlps and cause structural changes that result in the bacterium swimming toward nutrients and away from toxic chemicals. This ability allows the bacteria to successfully navigate through complex environments in an attempt to thrive and adapt. In order to explore the variability and diversity of Tlps in bacterial populations, this study used custom, high throughput in-house developed bioinformatics tools to look at: 1) Tlp distribution; and 2) how Tlps receptors contribute to bacterial survival/growth in different animals and environments. This information can help further understanding of how these bacteria cause illness in humans.

What are your most significant findings from this work?

Over 60 Campylobacter genomes were analyzed and it was found that each Campylobacter species or grouping of closely related Campylobacter isolates had characteristic Tlps. This finding is consistently observed, and supports the notion of separate tlp gene evolution during the formation of new Campylobacter species. Furthermore, the number of Tlps proteins and genetic variants was found to be far greater than previously thought. The tlp genes and protein sequences appear to undergo continuous adjustments to fine-tune the bacteria’s ability to thrive and cause infection. Despite this adaptability, there is often a single predominant Tlp type in the majority of bacteria per Campylobacter species. This trait can help in classifying bacteria and discriminate strains in disease surveillance.

What are the implications or impact of the research?

These research results have produced a finer scale of resolution in Campylobacter populations than previously thought possible. This finer resolution is based on the correlation of certain Tlps and their association with animal hosts, environmental niches, or highly infectious strains. Determining the Tlp type may help identify the infection source or mode of contamination. This classification of Tlps can be used to inform risk assessments of different Campylobacter species and of specific strains. It also provides an understanding of how different Campylobacter strains with different sets of Tlps are transmitted along the farm-to-fork continuum and emerge to cause human illness. This knowledge has the potential to target and control some strains of Campylobacter through vaccines and antimicrobials thereby reducing the public health impact of this infectious bacteria.

Additional References of Significance:

  • Kaakoush NO, Castaño-Rodríguez N, Mitchell HM, Man SM. Global epidemiology of Campylobacter infection. Clin Microbiol Rev 2015 Jul;28(3):687-720. doi: https://doi.org/10.1128/CMR.00006-15
  • Chandrashekar K, Kassem II, Rajashekara G. Campylobacter jejuni transducer like proteins: chemotaxis and beyond. Gut Microbes 2017 Jul 4;8(4):323-34. doi: https://doi.org/10.1080/19490976.2017.1279380
  • Korolik V, Ketley JM. Chemosensory signal transduction pathway of Campylobacter jejuni. In: Nachamkin I, Szymanski C, Blaser MJ, editors. Campylobacter. Washington, DC: ASM Press; 2008. pp. 351-66.
  • Day CJ, King RM, Shewell LK et al. A direct-sensing galactose chemoreceptor recently evolved in invasive strains of Campylobacter jejuni. Nat Commun 2016 Oct 20;7:13206. doi: https://doi.org/10.1038/ncomms13206



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