BACTERIOPHAGE RESEARCH

One of our central research thematics is the study of bacteriophages (phages for short). These small viruses infect bacteria, and they are found in almost all ecosystems where bacteria grow, including in and on our own body. In fact, the human gut contains a lot of phages, that together compose the "virome".  These phages are thought to play an important role in gut homeostasis, and in the control of gut bacterial populations, i.e. the "microbiome". Shifts in virome composition have been associated with diseases such as ulcerative colitis and Crohn's disease. Significant changes occur in viral composition during the first 2 years of life. Viruses are also thought to play some role in fecal microbiota transplantations (FMT), and could contribute to the success - or failure - of FMT in some cases.

In the Fortier Lab, we have developed a strong an internationally-recognised expertise in the study of phages infecting the human pathogen Clostridioides difficile (formerly Clostridium difficile). We have made several important contributions to our understanding of C. difficile phage diversity, phage-host interactions and how prophages, i.e. phages integrated into the genome of their bacterial host, can impact C. difficile virulence and lifestyle (see our publication list). Our lab also studies phages infecting other gut clostridia, in particular Clostridium perfringens, which is an important human pathogen, but that also causes necrotic enteritis in broiler chicken.

Strictly lytic phages (i.e. virulent) also represent an interesting option to fight multidrug resistant bacteria, and recent successful treatments revived the interest in phage therapy.

Our expertise goes from basic phage isolation to full microbiological characterization, including one-step growth curves, phage host range determination, morphological analysis using transmission electron microscopy (see picture on the left), whole structural protein analysis. We also sequence phage genomes and analyze their gene content, perform phylogenetic analyses to compare them, etc. We also developed PhageTerm, a software to determine the type of genomic termini that phages have inside the infectious particles.