Unveiling the culture of the mysterious Shigella bacteria

Faculty of Science
Chemistry and Biomolecular Sciences
Navoun Silué
Bacteria are all around us: in the soil, air, and water, in radioactive waste and even in our bodies. Their ability to prosper in extreme environments make them powerful allies, but also dangerous enemies.

Navoun Silué, a PhD candidate working with Professor François-Xavier Campbell-Valois, spent most of his doctoral studies unravelling and characterizing the genetic material of a family of harmful bacteria named Shigella. These bacteria cause shigellosis – a contagious infection of the large intestine that causes severe diarrhea.

Navoun discovered two new genes implicated in the pathogenicity of Shigella. In other words, he uncovered unknown pieces of the genetic material that allows Shigella to cause diarrheal diseases. His findings also bring new perspectives on the emergence of pathogenic bacteria from their non-pathogenic relatives. Navoun used refined techniques such as Droplet Digital Polymerase Chain Reaction (ddPCR) to investigate gene expression in the bacteria. Using immunoblotting, he characterized the proteins encoded by two of the mysterious genes. Various other molecular biology techniques were employed throughout the study, including mutagenesis, cloning and PCR.

In the frame of an international collaboration, Navoun is focusing on finding molecules that inhibit the pathogenicity of Shigella. He hopes that these new molecules or their derivatives can become a new treatment for Shigella’s infection. Following his PhD, Navoun wishes to pursue a career in research centered organizations such as the Public Health Agency of Canada. 

Navoun’s journey was filled with a plethora of obstacles. As an international student from Côte d’Ivoire, he struggled to find a PhD supervisor due to a lack of references to guarantee his expertise in Canada. He even took supplemental courses for “Special Students” at uOttawa to improve his chances of pursuing graduate studies. Following several rejections, Navoun’s perseverance finally landed him a position with Prof. Campbell-Valois. “Navoun is a precious collaborator, a real gem! I owe him a lot for his remarkable contribution as one of the founding members of my research team,” said Prof. Campbell-Valois. “Combined with his previous experience in a center for disease control in Côte d’Ivoire, his career objectives are within reach. I hope that Navoun’s success can be a testament to the accomplishments that francophone scientists from different parts of the world can achieve by working together at the University of Ottawa.” Navoun also attributes his success to the mentorship of Professor Daniel Figeys, who taught him several techniques through the TECHNOMISE NSERC-CREATE program.

Navoun advises future PhD students to “never dismiss any results no matter how aberrant they may seem, as they might lead to important discoveries in the future.” He emphasizes the importance of perseverance in a graduate student’s journey as “there will often be failures, but you can always bounce back.”

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