Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2018

Could environmental durability act as an enabler of bacterial pathogenicity? (#392)

Liang Wang 1 2 , Yangguang Du 3 , Jiawei Yan 4 , Qinghua Liu 2 , Zhanzhong Liu 4 , Charlene M Kahler 5 , Michael J Wise 5 6
  1. Department of Bioinformatics, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
  2. Key Laboratory of New Drug Research and Clinical Pharmacy of Jiangsu Province, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
  3. Xuzhou Center for Disease Control and Prevention, Xuzhou, Jiangsu Province, China
  4. Department of Laboratory Medicine, Xuzhou Infectious Diseases Hospital, Xuzhou, Jiangsu Province, China
  5. The Marshall Centre for Infectious Diseases Research and Training, University of Western Australia, Perth, WA, Australia
  6. Computer Science and Software Engineering, University of Western Australia, Perth, WA, Australia

Sit-and-wait hypothesis predicts that environmental durability is positively correlated with bacterial virulence for non-vector-borne pathogens, such as Mycobacterium tuberculosis and Pseudomonas aeruginosa, etc. A couple of recent studies confirmed that environmental durability plays important roles in microbial virulence, facilitating enhanced infection rates and increased virulence for Sphaerothecum destruens and Flavobacterium columnare, respectively [1, 2]. Søborg et al. noticed that virulence genes are widely distributed in environmental metagenomes, indicating that virulence factors might have advantages for bacterial survival outside the host environment [3]. However, proposal of the hypothesis is merely based on the epidemiological data reported by Walther and Ewald [4]. In addition, it is argued that sit-and-wait pathogens are rather rare in microbes. In order to understand how bacterial durability and virulence are correlated, Wang et al. investigated hundreds of bacterial proteomes through bioinformatics methods for durability- and virulence-related factors at the genomic level [5, 6]. Energy reserves such as glycogen and polyphosphate were included as indicators of durability for the preliminary studies [6, 7]. Results showed that bacteria with energy reserve metabolism are more likely to be durable in the environment. They also have more pathogenicity-related proteins, such as invasins and toxins etc., reflecting higher degree of virulence [7]. A further, detailed bioinformatics analysis into eight selected sit-and-wait pathogens confirmed that these species are tightly associated with high numbers of durability genes and virulence factors [5]. In contrast, three other bacterial categories, which are host-associated, obligate intracellular, and free-living, showed absence of durability genes or virulence factors [5]. Inter-group comparisons revealed significant differences between sit-and-wait pathogens and the other three groups [5]. The results of our bioinformatics analyses correspond well with epidemiological data presented previously [4]. Although the conclusions must be treat with caution due to limited experimental data, this preliminary study provides protein targets for investigating the sit-and-wait hypothesis and molecular experimental studies should be performed in order to provide evidence at the cellular and population levels.

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  4. Walther BA, Ewald PW. Pathogen survival in the external environment and the evolution of virulence. Biol Rev Camb Philos Soc 79(4), 849-869 (2004).
  5. Wang L, Liu Z, Dai S, Yan J, Wise MJ. The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence. Front Microbiol 8 2167 (2017).
  6. Wang L, Wise MJ. Glycogen with short average chain length enhances bacterial durability. Naturwissenschaften 98(9), 719-729 (2011).
  7. Wang L, Yan J, Wise MJ, Liu Q, Asenso J, Huang Y et al. Inorganic Polyphosphate Is Essential for Salmonella Typhimurium Virulence and Survival in Dictyostelium discoideum. Front Microbiol doi: (2018).