FEMS Microbiology Letters Poster Prize: Kavinda Tissera
Campylobacter, Helicobacter and Related Microorganisms Conference 2019 (CHRO2019)
FEMS Microbiology Letters awarded an Poster Presentation Prize at CHRO2019 to Kavinda Tissera. You can read an interview with Kavinda below.
What is your current position and what was your scientific journey to get there?
I’m a final year PhD student, studying the major of Applied Life Sciences in graduate school of Yonsei university, Seoul, South Korea. My current research interest is based on the pathogenesis of gastric cancer induced by Helicobacter pylori. I’m a Sri Lankan citizen.
I graduated with a B.Sc. in Medical Laboratory Science at the Faculty of Allied Health Sciences, University of Peradeniya, Sri Lanka. My final year research project was on “density and biodiversity of toxin producible cyanobacteria and the nitrate, nitrite, ammonium, dissolved phosphate, total phosphate, dissolved oxygen and pH levels in some reservoirs in CKD high prevalence areas in North Central Province of Sri Lanka.”
Then I did my M.Sc. in Medical Microbiology at the Post Graduate Institute of Science, University of Peradeniya. My M.Sc. research work on “spread of resistant gram negatives in a Sri Lankan intensive care unit” has been published in 2017. By recognizing this work, we have been awarded a ‘President’s Award for Scientific Publication’ organized by the National Research Council of Sri Lanka.
After finishing my masters I received a scholarship from the Yonsei university graduate school of dentistry to follow my ongoing PhD program. The research I presented was carried out by me with Dr. Hanfu Su and Dr. Sungil Jang, under the supervision of my mentor Prof. Jeong-Heon Cha.”
Could you describe the research your poster covered?
It was about suggesting an evolutionary mechanism behind the genesis of multi-cagA genotype in Helicobacter pylori. Severity of Helicobacter pylori-associated disease is directly linked with carriage of the CagA toxin. Our previous study revealed that some H. pylori strains underwent dynamic manipulation of cagA copy number and that increased copies of cagA correlate with the disease development.
Herein we explored the evolutionary mechanism leading to multi-cagA genotype. Therefore, we performed whole genome sequencing of six multi-cagA H. pylori strains and two single-cagA strains. Comparative genomic and phylogenetic analysis of 52 H. pylori strains isolated from different geographic regions were studied. Further experimental data were gained via generating and characterizing of H. pylori PMSS1 and G27 isogenic mutants in order to strengthen our hypothesis .
Our results showed that the all multi-cagA H. pylori strains belong to hpEurope. The further analysis divided hpEurope into two clades: hspEurope1 and hspEurope2. Only hspEurope2 displayed the multi-cagA genotype.
Furthermore, cagPAI appears to have been independently introduced into two different H. pylori groups, termed pre-type-A and pre-type-B, which consequently evolved to cagPAI type-A and type-B, respectively; importantly, all multi-cagA genotype strains displayed cagPAI type-B. Two direct cagA-flanking repeats of a genetic element termed CHA-ud were essential for the multi-cagA genotype in strain PMSS1 (hspEurope2 and type-B).
Furthermore, we have shown that the introduction of this genetic element into strain G27 (hspEurope1 and type-A) was sufficient to generate the multi-cagA genotype. The critical steps in the evolution of the multi-cagA genotype involved creation of CHA-ud at cagA upstream in cagPAI type-B strains followed by its duplication to cagA downstream.
We concluded that the investigation of the evolutionary mechanism leading to the multi-cagA genotypes may improve the comprehension of how H. pylori evolved with the interaction of its host.”
What do you hope to focus your research on in the future?
We hope to study how H. pylori modulate cagA copies in-vivo under different host and environmental factors.”
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