BorMax, a Novel Dhillonvirus Infecting MDR Escherichia coli: Genomic Insights, Taxonomic Position, and Anti-CRISPR Repertoire

Escherichia coli is a major pathogen responsible for urinary tract infections, septicemia, and other clinically relevant conditions, with increasing multidrug resistance (MDR) limiting available treatment options. In this context, bacteriophages represent a valuable resource for exploring novel antimicrobial and biotechnological tools. Here, we report the isolation and genomic characterization of BorMax, a novel lytic phage infecting multiple MDR E. coli. Transmission electron microscopy revealed a tailed morphology consistent with Dhillonvirus. Whole genome sequencing and de novo assembly showed a linear double-stranded DNA genome of 45,502 bp, encoding 70 predicted coding sequences (CDSs) and lacking tRNAs. Bioinformatic analyses confirmed the absence of lysogeny-associated genes, as well as virulence and antimicrobial resistance determinants. Comparative genomics using classified BorMax within the genus Dhillonvirus as a new species, sharing <77% intergenomic similarity with known members. Notably, predictions using PaCRISPR and AcRanker identified four CDSs with strong anti-CRISPR (Acr) potential, representing previously undescribed Acr candidates in this group. These genomic features highlight the novelty, safety, and potential biotechnological relevance of BorMax and contribute to the expanding genomic and functional diversity of Dhillonvirus and E. coli-infecting phages.