A lytic Providencia rettgeri virus of potential therapeutic value is a deep-branching member of the T5virus genus

Abstract

Providencia rettgeri is emerging as a new opportunistic pathogen with high antibiotic resistance. The need to find alternative methods to control antibiotic-resistant bacteria and the recent advances in phage therapy motivate the search for new phages able to infect Providencia spp. This study describes the isolation and characterization of an obligatory lytic phage, vB_PreS_PR1 (PR1), with therapeutic potential against drug-resistant P. rettgeri. PR1 is a siphovirus. Its virion DNA size (118,537 bp), transcriptional organization, terminal repeats (10,461 bp), and nicks in the 3-to-5 strand are similar to those of phage T5. However, sequence similarities of PR1 to phages of the T5virus genus at the DNA and protein levels are limited, suggesting that it belongs to a new species within the Siphoviridae family. PR1 exhibits the ability to kill P. rettgeri antibiotic-resistant strains, is highly specific to the species, and did not present known genomic markers indicating a temperate lifestyle. The lack of homologies between its proteins and proteins of the only other sequenced Providencia prophage, Redjac, suggests that these two phages evolved separately and may target different host proteins.