Lytic Myophage Abp53 Encodes Several Proteins Similar to Those Encoded by Host Acinetobacter baumannii and Phage phiKO2

Abstract

Acinetobacter baumannii is an important Gram-negative opportunistic pathogen causing nosocomial infections. The emergence of multiple-drug-resistant A. baumannii isolates has increased in recent years. Directed toward phage therapy, a lytic phage of A. baumannii, designated Abp53, was isolated from a sputum sample in this study. Abp53 has an isometric head and a contractile tail with tail fibers (belonging to Myoviridae), a latent period of about 10 min, and a burst size of approximately 150 PFU per infected cell. Abp53 could completely lyse 27% of the A. baumannii isolates tested, which were all multiple drug resistant, but not other bacteria. Mg 2؉ enhanced the adsorption and productivity of, and host lysis by, Abp53. Twenty Abp53 virion proteins were visualized in SDS-polyacrylamide gel electrophoresis, with a 47-kDa protein being the predicted major capsid protein. Abp53 has a double-stranded DNA genome of 95 kb. Sequence analyses of a 10-kb region revealed 8 open reading frames. Five of the encoded proteins, including 3 tail components and 2 hypothetical proteins, were similar to proteins encoded by A. baumannii strain ACICU. ORF1176 (one of the tail components, 1,176 amino acids [aa]), which is also similar to tail protein gp21 of Klebsiella phage phiKO2, contained repeated domains similar to those within the ACICU_02717 protein of A. baumannii ACICU and gp21. These findings suggest a common ancestry and horizontal gene transfer during evolution. As phages can expand the host range by domain duplication in tail fiber proteins, repeated domains in ORF1176 might have a similar significance in Abp53.

Characterization and Detection of Endolysin Gene from Three Acinetobacter baumannii Bacteriophages Isolated from Sewage Water

“…Bacteriophage ØABP-02 and ØABP-04 were classified into the family Myoviridae. This family was also reported in bacteriophages ABp53, ZZ1 and AP22 [16,18,19].…”

“…ØABP-01 had a shorter latent period and displayed good lytic activity compared to other bacteriophage isolates. Previous reports of bacteriophages infecting A. baumannii showed latent periods ranging from 9 to 25 min and burst size from 22 to 409 PFU/infected cell [14][15][16][18][19][20][21][22].…”

“…To date, most of A. baumannii bacteriophage isolates are DNA phages [14,15,16,18,19,22]. PFGE analysis revealed that phage DNA ØABP-01 and ØABP-04 have genome sizes of approximately 30 kb and ØABP-02 showed a larger genome size of approximately 240 kb (Fig.…”

“…Phage endolysins have been studied in a variety of pathogenic bacteria including A. baumannii for theirs antibacterial activity [11][12][13]. In the past three years, A. baumannii bacteriophages and endolysin have been isolated and characterized [14][15][16][17][18][19][20][21][22][23][24]. However, there are geographic differences in A. baumannii host strains.…”

Complete Genome Sequence of the Podoviral Bacteriophage YMC/09/02/B1251 ABA BP, Which Causes the Lysis of an OXA-23-Producing Carbapenem-Resistant Acinetobacter baumannii Isolate from a Septic Patient

“…Recently, the emergence of multidrug-resistant A. baumannii strains that are even resistant to carbapenem, the last resort for the treatment of severe Gram-negative bacterial infections, has increased worldwide concerns (5,6). In this study, we reveal a novel carbapenem-resistant A. baumannii lytic bacteriophage, 〉-B1251 (YMC/09/02/B1251 ABA BP), which was isolated from a sewage sample obtained from a university hospital in South Korea.…”