Exploring prophages in Salmonella enterica: an in-silico approach

Prophages play a crucial role in shaping host physiology, influencing traits such as virulence and antimicrobial resistance. In Salmonella enterica, prophages can constitute up to 30% of the accessory genome, contributing significantly to its genetic diversity and adaptability. In this study, we employed an in-silico approach to identify prophages within S. enterica genomes obtained poultry and clinical isolates. A total of 151 S. enterica sequences were assembled using SPAdes and subsequently quality-filtered with Abyss and BUSCO. Prophage sequences were detected using Phigaro and CheckV, followed by quality assessment with PHASTEST. The identification was performed using a custom database comprising 60 S. enterica prophages from previous studies. Comparative genomics, including gene annotation and recombination detection, were performed on representative prophages. Virulence genes were identified using VFDB and VirulenceFinder databases. Lastly, phylogenetic analysis of the prophages was carried out based on terminase and integrase sequences. We obtained 142 S. enterica genomes to analyze their prophage content. Peduovirus pro483 was highly prevalent among S. Infantis isolates and carried two cargo proteins: an Imma/Irre metalloendopeptidase and a fimbrial protein. In contrast, a related S. Enteritidis isolate also harboring Peduovirus pro483 carried a different set of cargo genes--HEPN-MAE-28990 and a cytosine-specific methyltransferase--suggesting horizontal transfer or a recent phage acquisition event. Enterobacteria phage ST104, found in S. Typhimurium, exhibited nearly complete identity to its reference and encoded superinfection exclusion proteins (SieA, SieB), enhancing phage resistance. Phylogenetic analyses supported their classification and revealed distinct evolutionary relationships tied to host serovar and environment. To our knowledge, this is the first study to describe prophage diversity in S. enterica strains isolated from Ecuadorian poultry farms, providing insights into their potential role in strain adaptation and public health relevance.