Genetic Exchanges Shape the Evolutionary Diversification Among Shigella phages.

Shigella is a genus of bacteria that is a prevalent cause of bacterial diarrhoea (i.e., shigellosis). Shigella bacteriophages are shaping bacterial fitness. Bacteriophages can carry genes that contribute to Shigella virulence and antibiotic resistance, and these genes are frequently found on mobile genetic elements (MGEs). Horizontal gene transfer (HGT) of these components is a major driver of bacterial evolution. A comprehensive genomic analysis of these bacteriophages is required to deepen understanding of candidate genes for MGEs and HGTs. Through genetic exchange, phages acquire novel genetic features that confer selective advantages. In this study, we identified the weighted gene repertoire relatedness (wGRR) metric. We associated it with the infecting host species andgenetic exchanges among Shigella phages using the weighted gene repertoire relatedness (wGRR) metric. We associated them with the infecting host species and phage lifestyles to examine evolutionary constraints among phages. We observed that HGTs can affect genes' GC content, which, in turn, influences amino acid usage, thereby shaping the amino acid usage of the resulting proteins. Host-range expansion is also observed among Shigella phages. However, we also noted that Shigella phages do not have the propensity for genetic transfer with dissimilar lifestyles. The gene pool of bacteriophages, due to horizontal transfer, can broaden their host range, making them more suitable for applications in phage therapy against antibiotic-resistant bacteria. Horizontal gene transfer can expand the bacteriophage gene pool, thereby increasing host range and making them more suitable for phage therapy against antibiotic-resistant bacteria. Overall, this study provides deeper insight into MGEs and HGTs among Shigella phages and their evolutionary significance for infectivity.