Isolation and Characterization of AbTJ, an Acinetobacter baumannii Phage, and Functional Identification of Its Receptor-Binding Modules

Abstract

A. baumannii is an opportunistic pathogen and a major cause of various community-acquired infections. Strains of this species can be resistant to multiple antimicrobial agents, leaving limited therapeutic options, also lacking in methods for accurate and prompt diagnosis. In this context, AbTJ, a novel phage that infects A. baumannii MDR-TJ, was isolated and characterized, together with its two tail fiber proteins. Morphological analysis revealed that it belongs to Podoviridae family. Its host range, growth characteristics, stability under various conditions, and genomic sequence, were systematically investigated. Bioinformatic analysis showed that AbTJ consists of a circular, double-stranded 42670-bp DNA molecule which contains 62 putative open reading frames (ORFs). Genome comparison revealed that the phage AbTJ is related to the Acinetobacter phage Ab105-1phi (No. KT588074). Tail fiber protein (TFPs) gp52 and gp53 were then identified and confirmed as species-specific proteins. By using a combination of bioluminescent methods and magnetic beads, these TFPs exhibit excellent specificity to detect A. baumannii. The findings of this study can be used to help control opportunistic infections and to provide pathogen-binding modules for further construction of engineered bacteria of diagnosis and treatment.

Isolation and Characterization of a Novel Autographiviridae Phage and Its Combined Effect with Tigecycline in Controlling Multidrug-Resistant Acinetobacter baumannii-Associated Skin and Soft Tissue Infections

“…Phage vABWU2101 could adsorb into host cells rapidly. Previous studies on Podoviridae and Autographiviridae phages showed a latency period of 15-90 min and burst size of 70-300 particles per infected cell [58,59]. Phage vABWU2101 had a short latency period and a large burst size when compared with these earlier reports.…”

“…However, the phage classification was confirmed by genomic analysis. Several Podoviridae or Autographiviridae phages specific for A. baumannii have been studied, such as phage SH-Ab 15497 [57], phage AbTJ [58], phage vB_AbaP_AS11, phage vB_AbaP_AS12 [59], and phage Aristophane [60]. Based on the spot test and the EOP analysis, phage vABWU2101 was found to be specific for A. baumannii strains and had a narrow host range activity.…”

Alteromonas Myovirus V22 Represents a New Genus of Marine Bacteriophages Requiring a Tail Fiber Chaperone for Host Recognition

“…Indeed, even when phage tails have similar morphologies, it is unusual that they recognize similar targets, explaining the high specificity observed in phage-host recognition systems (27). In this sense, RBPs can be exploited, for example, as tools for bacterial diagnostics (29)(30)(31)(32)(33).…”

Functional domains of Acinetobacter bacteriophage tail fibers

“…These phages include AP22 (gp54), APK32 (gp46), APK48 (gp43), P1 (gp43), B9 (gp69), and TaPaz (gp79) (Oliveira et al, 2017 , 2018 ; Knirel et al, 2020 ; Popova et al, 2020a ; Shchurova et al, 2021 ). Furthermore, halo formation was detailed in the following phages but the protein responsible was not confirmed: AbTj (gp53) and WCHABP1 (gp5) (Zhou et al, 2018 ; Xu et al, 2020 ; Drobiazko et al, 2022 ). All the eight abovementioned proteins were modeled as homotrimers with AlphaFold Multimer and showed narrow midsections and larger globular regions ( Figure 7 ).…”