Genomic and biological characterization of ΦAB114, a temperate siphovirus infecting colistin- and carbapenem-resistant Acinetobacter baumannii.
Abstract
Acinetobacter baumannii is a prominent opportunistic pathogen responsible for healthcare-associated infections. Its increasing association with multidrug resistance (MDR) severely constrains current therapeutic options, underlining the urgent need for alternative antimicrobial strategies. In this study, we aimed to isolate and comprehensively characterize a novel bacteriophage, ΦAB114, targeting MDR A. baumannii through morphological, biological, and genomic analyses. ΦAB114 was characterized using transmission electron microscopy (TEM), host range analysis, and Illumina-based whole-genome sequencing (WGS). Functional genome annotation, comparative genomics, and phylogenetic analyses were performed to determine its genetic features, evolutionary relationships, and the presence of antibiotic resistance or virulence-associated genes. TEM analysis revealed that ΦAB114 exhibits a siphovirus-like morphology and belongs to the class Caudoviricetes. ΦAB114 was able to infect 20 of 72 clinical A. baumannii isolates, including carbapenem- and colistin-resistant strains WGS identified a putatively linear double-stranded DNA genome of 37,423 bp with a GC content of 39.76%, encoding 55 putative ORFs. Functional annotation revealed genes involved in structural assembly, DNA packaging, replication, and regulation, while an integrase gene suggested a temperate lifestyle. Comparative genomic and phylogenetic analyses showed high sequence similarity to Acinetobacter phages Ab105-1phi and AbTJ. No antibiotic resistance or virulence-associated genes were detected. The genomic characteristics of ΦAB114, the absence of detectable antimicrobial resistance and virulence genes, and its observed activity against MDR A. baumannii clinical isolates contribute to the genomic and biological characterization of this temperate phage, underscoring the need for further experimental studies to fully evaluate its biological behavior and potential applications.