Characterization of Pseudomonas aeruginosa Phage C11 and Identification of Host Genes Required for Virion Maturation

Abstract

The underlying mechanisms of phage-host interactions largely remained to be elucidated. In this work, Pseudomonas aeruginosa phage C11 was first characterized as a Myoviridae virus having a linear dsDNA molecule of 94109 bp with 1173 bp identical terminal direct repeats (TDR). Then the mutants resistant to phage C11 were screened in a Tn5G transposon mutant library of P. aeruginosa PAK, including two mutants with decreased adsorption rates (DAR) and five mutants with wild-type adsorption rates (WAR). When the WAR mutants were incubated with phage C11, their growth rates were significantly inhibited; the replication of the phage genomic DNA was detected in all the WAR mutants with the real-time quantitative PCR analysis; and the synthesized phage genomic DNA was processed into monomers for packaging evidenced by the southern blot analysis. Moreover, with strain PAK as indicator, small quantities of phage C11 were synthesized in the WAR mutants. Taken together, these data suggested the identified genes of the WAR mutants are necessary for efficient synthesis of the infectious phage particles. Finally, the WAR mutants were detected sensitive to two other Pseudomonas phages closely related with C11, further implying the evolved diversity and complexity of the phage-host interactions in both sides.

Quantitative Models of Phage-Antibiotic Combination Therapy

“…Finally, we note that these results derived from analysis of dynamics arising among extreme phenotypes. In reality, phage-sensitive strains may retain some sensitivity to antibiotics and antibiotic-sensitive strains can be infected at reduced levels by phage (7,23,24). Hence, we repeated the robustness analysis, using an extended model that incorporates quantitatively different levels of phage infectivity and antibiotic sensitivity of both strains (see Text S2).…”

Dual bioresponsive antibiotic and quorum sensing inhibitor combination nanoparticles for treatment of Pseudomonas aeruginosa biofilms in vitro and ex vivo

“…Finally, we opted for ciprofloxacin (CIP) as the antibiotic, as its positive charge at ambient pH values facilitated association with the alginate carboxylates and induced self-assembly of the system into NPs of sizes (150-200 nm) similar to those of Pseudomonas bacteriophages. 37 The synthetic scheme for the construction of the dual bioresponsive combination therapeutic nanoparticles is shown in Scheme 1.…”

“…36 The combined formulation thus consisted of alginate-based nanoparticles (NPs), containing CIP encapsulated by chargecharge interactions during a nanoprecipitation process, with ACNQ attached via a pH-responsive hydrazine linker, and of a size range (150-200 nm) similar to those of Pseudomonas bacteriophages. 37 We then tested these formulations as synergistic adjuvant-drug therapeutics in infection models consisting of pre-established biofilms of P. aeruginosa PAO1-Nottingham subline (PAO1-N) of ≥100 µm thickness in vitro and in both 2D and 3D skin infection models. The formulation and anti-infective action is shown schematically in Fig.…”

Quantitative Models of Phage-Antibiotics Combination Therapy

“…Finally, we note that these results derived from analysis of dynamics arising among extreme phenotypes. In reality, phage-sensitive strains may retain some sensitivity to antibiotics and antibiotic-sensitive strains can be infected at reduced levels by phage 7, 23,24 . Hence, we repeated the robustness analysis, using an extended model that incorporates quantitatively different levels of phage-infectivity and antibiotic-sensitivity of both strains (see Supplementary Text S2).…”