Germán Sgro

Bacteriophages (phages) are viruses that infect bacteria, and are the smallest and most abundant biological entities on Earth. To replicate, they use the bacterial host machinery to either i) produce new progeny immediately after infection, leading to the death of the infected cell (lytic pathway), or ii) integrate into the bacterial chromosome as a prophage, establishing a symbiotic relationship between the parties (lysogenic pathway). The interaction begins with the recognition and adsorption of the phage on the surface of the bacterium, which determines the specificity and host range. Most known phages have a narrow host range, usually infecting specific strains or isolates of a particular bacterial species. For such recognition, virions have specific proteins that bind to receptors located on the bacterial surface, such as lipopolysaccharide (LPS), exopolysaccharide (EPS), outer membrane proteins (OMPs), fimbriae, pili and flagella. In recent decades, the interest in the use of phages as therapeutic agents (phage therapy) in the biological control of infections by multidrug-resistant bacteria has increased, as well as in the development of strategies for the biocontrol of pathogenic species in agricultural crops. In this context, understanding the molecular mechanisms underlying phage-bacteria interactions is crucial to obtain information on how phages affect microbial populations and how they can be used in clinical and biotechnological applications. Here, we present our results about the high-resolution molecular structures involved in the infectious process of lytic bacteriophages that interact and infect bacterial strains of relevance in medicine and agriculture.