Equine intestinal O-seroconverting temperate coliphage Hf4s: genomic and biological characterization

Tailed bacteriophages constitute the bulk of the intestinal viromes of the vertebrate animals. However, the relationships between lytic and lysogenic lifestyles of the phages in these ecosystems are not always clear and may vary between the species or even between the individuals. The human intestinal (fecal) viromes are believed to be dominated by temperate phages, while in the horse feces the virulent phages are more prevalent. Almost all the isolates of horse fecal coliphages are virulent. Phage Hf4s is the first temperate equine intestinal coliphage characterized. It was isolated from the horse feces on the indigenous equine E. coli 4s strain. It is a podovirus, related to Lederbergvirus genus (including the well-characterized Salmonella phage P22). Hf4s recognizes the host O antigen as its primary receptor and possesses a functional O-antigen seroconversion cluster that renders the lysogens protected from the superinfection by the same phage and also abolishes the adsorption of some indigenous equine virulent coliphages, such as DT57C, while the other phages, such as G7C or phiKT retain the ability to infect E. coli 4s (Hf4s) lysogens. ImportanceThe relationships between virulent and temperate bacteriophages and their impact on high-density symbiotic microbial ecosystems of the animal are not always clear and may vary between the species or even between the individuals. The horse intestinal virome is dominated by the virulent phages, and Hf4s is the first temperate equine intestinal coliphage characterized. It recognizes the host O antigen as its primary receptor and possesses a functional O-antigen seroconversion cluster that renders the lysogens protected from the superinfection by some indigenous equine virulent coliphages, such as DT57C, while the other phages, such as G7C or phiKT retain the ability to infect E. coli 4s (Hf4s) lysogens. microbial viruses in the mammal intestinal ecosystems.