The Resistance of Vibrio cholerae O1 El Tor Strains to the Typing Phage 919TP, a Member of K139 Phage Family

Abstract

Bacteriophage 919TP is a temperate phage of Vibrio cholerae serogroup O1 El Tor and is used as a subtyping phage in the phage-biotyping scheme in cholera surveillance in China. In this study, sequencing of the 919TP genome showed that it belonged to the Vibrio phage K139 family. The mechanisms conferring resistance to 919TP infection of El Tor strains were explored to help understand the subtyping basis of phage 919TP and mutations related to 919TP resistance. Among the test strains resistant to phage 919TP, most contained the temperate 919TP phage genome, which facilitated superinfection exclusion to 919TP. Our data suggested that this immunity to Vibrio phage 919TP occurred after absorption of the phage onto the bacteria. Other strains contained LPS receptor synthesis gene mutations that disable adsorption of phage 919TP. Several strains resistant to 919TP infection possessed unknown resistance mechanisms, since they did not contain LPS receptor mutations or temperate K139 phage genome. Further research is required to elucidate the phage infection steps involved in the resistance of these strains to phage infection.

Prevalence and Diversity Analysis of Candidate Prophages to Provide An Understanding on Their Roles in Bacillus Thuringiensis

“…Among these nine strains, the culture supernatants of the 4CC1, 4AJ1, HD-1, 4BD1, HD521, and BMB171 strains showed broad lytic ranges and could lyse 31, 41, 21, 18, 33 of the 45 tested Bt strains, separately (Table S5). The incompatibility of phages can inhibit the infection of phages with highly similar genomes due to superinfection exclusion [48,49]. One interesting finding in this study is that the phages (or phage) induced from the 4AJ1 strain could infect the original 4AJ1 strain, which might be because the complete prophage in strain 4AJ1 lacked the mechanism that could provide the strain with resistance to the induced phage.…”

Interactions between the Prophage 919TP and Its Vibrio cholerae Host: Implications of gmd Mutation for Phage Resistance, Cell Auto-Aggregation, and Motility

“…V. cholerae O1 El Tor strain Vc1 carries prophage 919TP, which can be spontaneously induced and is poorly propagated in the V. cholerae host strain SM6 [3]. Basic characterization of the induced phage ϕ919TP and its interactions with SM6 has been provided recently [3].…”

“…However, V. cholerae also contains prophages that follow the lysogenic life cycle, where temperate phages are spontaneously induced, thereby killing their host. Despite V. cholerae being a highly studied model bacterium and an important human pathogen, the role of several prophages and the corresponding free phage particles, such as phage ϕ919TP, remain to be experimentally characterized [3]. Genome sequencing shows that phage ϕ919TP is a lambda-like phage, carrying a CI repressor, which in phage lambda governs the lysis/lysogeny switch in the host cells.…”

“…Specifically, when CI repressor concentration is high, it represses the development of the lytic life cycle of the prophage [4]. However, experimental evidence of its function in 919TP-prophages containing V. cholerae strains is lacking [3]. In addition, previous work suggested that lipopolysaccharide (LPS) plays an important role in adsorption and infection by the ϕ919TP phage particle [2].…”

Novel approaches to the treatment of bacterial biofilm infections

“…One possible obstacle to the widespread adoption of phage therapy is the development of bacteria resistant to phage infection. Common mechanisms of resistance relate to changes in the membrane‐based targets including lipopolysaccharide, which prevent phage adsorption (Shen et al, ). It is possible that cocktails of phage with multiple targets can be developed to minimize this risk, although bacteria resistant to phage they encounter in their normal habitats are common.…”