Agtrevirus phage AV101 recognizes four different O-antigens infecting diverse E. coli

Abstract

Bacteriophages in the Agtrevirus genus are known for expressing multiple tail spike proteins (TSPs), but little is known about their genetic diversity and host recognition apart from their ability to infect diverse Enterobacteriaceae species. Here we aim to determine the genetic differences that may account for the diverse host ranges of Agrevirus phages. We performed comparative genomics of 14 Agtrevirus and identified only a few genetic differences including genes involved in nucleotide metabolism. Most notably was the diversity of the tsp gene cluster, specifically in the receptor binding domains that were unique among most of the phages. We further characterized agtrevirus AV101 infecting nine diverse Extended Spectrum β-lactamase (ESBL) E. coli and demonstrated that this phage encoded four unique TSPs among Agtrevirus. Purified TSPs formed translucent zones and inhibited AV101 infection of specific hosts, demonstrating that TSP1, TSP2, TSP3, and TSP4 recognize O8, O82, O153, and O159 O-antigens of E. coli, respectively. BLASTp analysis showed that the receptor binding domain of TSP1, TSP2, TSP3 and TSP4 are similar to TSPs encoded by E. coli prophages and distant related virulent phages. Thus, Agtrevirus may have gained their receptor binding domains by recombining with prophages or virulent phages. Overall, combining bioinformatic and biological data expands the understanding of TSP host recognition of Agtrevirus and give new insight into the origin and acquisition of receptor binding domains of Ackermannviridae phages.

The branched receptor binding complex ofAckermannviridaephages promotes adaptative host recognition

“…This domain recognizes polysaccharides as receptors like lipopolysaccharide (LPS), exopolysaccharides (EPS), and capsular polysaccharides (CPS), allowing the phages to infect diverse bacteria belonging to the Enterobacteriaceae 8,10–14 . We previously analyzed the TSP diversity in the Kuttervirus , Agtrevirus , Limestonevirus , and Taipeivirus genera of the Ackermannviridae family 12,15 . Interestingly, a large pool of genetic diversity of receptor binding domains was revealed, suggesting that phage receptor binding proteins have been diversified to match the multitude of variations of O-antigen and K-antigens expressed by Enterobacteriaceae 8,10,12,13 .…”