A Tail Fiber Protein and a Receptor-Binding Protein Mediate ICP2 Bacteriophage Interactions with Vibrio cholerae OmpU

AbstractICP2 is a virulent bacteriophage (phage) that preys on Vibrio cholerae. ICP2 was first isolated from cholera patient stool samples. Some of these stools also contained ICP2-resistant isogenic V. cholerae strains harboring missense mutations in the trimeric outer membrane porin protein OmpU, identifying it as the ICP2 receptor. In this study, we identify the ICP2 proteins that mediate interactions with OmpU by selecting for ICP2 host-range mutants within infant rabbits infected with a mixture of wild type and OmpU mutant strains. ICP2 host-range mutants had missense mutations in putative tail fiber gene gp25 and putative adhesin gp23. Using site-specific mutagenesis we show that single or double mutations in gp25 are sufficient to generate the host-range mutant phenotype. However, at least one additional mutation in gp23 is required for robust plaque formation on specific OmpU mutants. Mutations in gp23 alone were insufficient to give a host-range mutant phenotype. All ICP2 host-range mutants retained the ability to plaque on wild type V. cholerae cells. The strength of binding of host-range mutants to V. cholerae correlated with plaque morphology, indicating that the selected mutations in gp25 and gp23 restore molecular interactions with the receptor. We propose that ICP2 host-range mutants evolve by a two-step process where, first, gp25 mutations are selected for their broad host-range, albeit accompanied by low level phage adsorption. Subsequent selection occurs for gp23 mutations that further increase productive binding to specific OmpU alleles, allowing for near wild type efficiencies of adsorption and subsequent phage multiplication.ImportanceConcern over multidrug-resistant bacterial pathogens, including Vibrio cholerae, has led to a renewed interest in phage biology and their potential for phage therapy. ICP2 is a genetically unique virulent phage isolated from cholera patient stool samples. It is also one of three phages in a prophylactic cocktail shown to be effective in animal models of infection and the only one of the three that requires a protein receptor (OmpU). This study identifies a ICP2 tail fiber and a receptor binding protein and examines how ICP2 responds to the selective pressures of phage-resistant OmpU mutants. We found that this particular co-evolutionary arms race presents fitness costs to both ICP2 and V. cholerae.

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A Tail Fiber Protein and a Receptor-Binding Protein Mediate ICP2 Bacteriophage Interactions with Vibrio cholerae OmpU

Journal of Bacteriology ◽

10.1128/jb.00141-21 ◽

2021 ◽

Author(s):

Andrea N.W. Lim ◽

Minmin Yen ◽

Kimberley D. Seed ◽

David W. Lazinski ◽

Andrew Camilli

Keyword(s):

Host Range ◽

Vibrio Cholerae ◽

Receptor Binding ◽

Mutant Phenotype ◽

Tail Fiber ◽

Missense Mutations ◽

Wild Type ◽

Mutant Strains ◽

Stool Samples ◽

Receptor Binding Protein

ICP2 is a virulent bacteriophage (phage) that preys on Vibrio cholerae. ICP2 was first isolated from cholera patient stool samples. Some of these stools also contained ICP2-resistant isogenic V. cholerae strains harboring missense mutations in the trimeric outer membrane porin protein OmpU, identifying it as the ICP2 receptor. In this study, we identify the ICP2 proteins that mediate interactions with OmpU by selecting for ICP2 host-range mutants within infant rabbits infected with a mixture of wild type and OmpU mutant strains. ICP2 host-range mutants, that can now infect OmpU mutant strains, had missense mutations in putative tail fiber gene gp25 and putative adhesin gp23. Using site-specific mutagenesis we show that single or double mutations in gp25 are sufficient to generate the host-range mutant phenotype. However, at least one additional mutation in gp23 is required for robust plaque formation on specific OmpU mutants. Mutations in gp23 alone were insufficient to give a host-range mutant phenotype. All ICP2 host-range mutants retained the ability to plaque on wild type V. cholerae cells. The strength of binding of host-range mutants to V. cholerae correlated with plaque morphology, indicating that the selected mutations in gp25 and gp23 restore molecular interactions with the receptor. We propose that ICP2 host-range mutants evolve by a two-step process where, first, gp25 mutations are selected for their broad host-range, albeit accompanied by low level phage adsorption. Subsequent selection occurs for gp23 mutations that further increase productive binding to specific OmpU alleles, allowing for near wild type efficiencies of adsorption and subsequent phage multiplication. Importance Concern over multidrug-resistant bacterial pathogens, including Vibrio cholerae, has led to a renewed interest in phage biology and their potential for phage therapy. ICP2 is a genetically unique virulent phage isolated from cholera patient stool samples. It is also one of three phages in a prophylactic cocktail shown to be effective in animal models of infection and the only one of the three that requires a protein receptor (OmpU). This study identifies an ICP2 tail fiber and a receptor binding protein and examines how ICP2 responds to the selective pressures of phage-resistant OmpU mutants. We found that this particular co-evolutionary arms race presents fitness costs to both ICP2 and V. cholerae.

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Mapping the Tail Fiber as the Receptor Binding Protein Responsible for Differential Host Specificity of Pseudomonas aeruginosa Bacteriophages PaP1 and JG004

PLoS ONE ◽

10.1371/journal.pone.0068562 ◽

2013 ◽

Vol 8 (7) ◽

pp. e68562 ◽

Cited By ~ 63

Author(s):

Shuai Le ◽

Xuesong He ◽

Yinling Tan ◽

Guangtao Huang ◽

Lin Zhang ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Host Specificity ◽

Receptor Binding ◽

Binding Protein ◽

Tail Fiber ◽

Differential Host ◽

Receptor Binding Protein

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Dissecting the Role of E2 Protein Domains in Alphavirus Pathogenicity

Journal of Virology ◽

10.1128/jvi.02792-15 ◽

2015 ◽

Vol 90 (5) ◽

pp. 2418-2433 ◽

Cited By ~ 12

Author(s):

James Weger-Lucarelli ◽

Matthew T. Aliota ◽

Nathan Wlodarchak ◽

Attapon Kamlangdee ◽

Ryan Swanson ◽

...

Keyword(s):

Host Range ◽

Receptor Binding ◽

Chikungunya Virus ◽

Semliki Forest Virus ◽

Binding Protein ◽

Protein Domain ◽

Cdna Clones ◽

E2 Protein ◽

Receptor Binding Protein

ABSTRACTAlphaviruses represent a diverse set of arboviruses, many of which are important pathogens. Chikungunya virus (CHIKV), an arthritis-inducing alphavirus, is the cause of a massive ongoing outbreak in the Caribbean and South America. In contrast to CHIKV, other related alphaviruses, such as Venezuelan equine encephalitis virus (VEEV) and Semliki Forest virus (SFV), can cause encephalitic disease. E2, the receptor binding protein, has been implicated as a determinant in cell tropism, host range, pathogenicity, and immunogenicity. Previous reports also have demonstrated that E2 contains residues important for host range expansions and monoclonal antibody binding; however, little is known about what role each protein domain (e.g., A, B, and C) of E2 plays on these factors. Therefore, we constructed chimeric cDNA clones between CHIKV and VEEV or SFV to probe the effect of each domain on pathogenicityin vitroandin vivo. CHIKV chimeras containing each of the domains of the E2 (ΔDomA, ΔDomB, and ΔDomC) from SFV, but not VEEV, were successfully rescued. Interestingly, while all chimeric viruses were attenuated compared to CHIKV in mice, ΔDomB virus showed similar rates of infection and dissemination inAedes aegyptimosquitoes, suggesting differing roles for the E2 protein in different hosts. In contrast to CHIKV; ΔDomB, and to a lesser extent ΔDomA, caused neuron degeneration and demyelination in mice infected intracranially, suggesting a shift toward a phenotype similar to SFV. Thus, chimeric CHIKV/SFV provide insights on the role the alphavirus E2 protein plays on pathogenesis.IMPORTANCEChikungunya virus (CHIKV) has caused large outbreaks of acute and chronic arthritis throughout Africa and Southeast Asia and has now become a massive public health threat in the Americas, causing an estimated 1.2 million human cases in just over a year. No approved vaccines or antivirals exist for human use against CHIKV or any other alphavirus. Despite the threat, little is known about the role the receptor binding protein (E2) plays on disease outcome in an infected host. To study this, our laboratory generated chimeric CHIKV containing corresponding regions of the Semliki Forest virus (SFV) E2 (domains A, B, and C) substituted into the CHIKV genome. Our results demonstrate that each domain of E2 likely plays a critical, but dissimilar role in the viral life cycle. Our experiments show that manipulation of E2 domains can be useful for studies on viral pathogenesis and potentially the production of vaccines and/or antivirals.

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