The temperate Burkholderia phage AP3 of the Peduovirinae shows efficient antimicrobial activity against B. cenocepacia of the IIIA lineage

Abstract

Burkholderia phage AP3 (vB_BceM_AP3) is a temperate virus of the Myoviridae and the Peduovirinae subfamily (P2likevirus genus). This phage specifically infects multidrug-resistant clinical Burkholderia cenocepacia lineage IIIA strains commonly isolated from cystic fibrosis patients. AP3 exhibits high pairwise nucleotide identity (61.7 %) to Burkholderia phage KS5, specific to the same B. cenocepacia host, and has 46.7–49.5 % identity to phages infecting other species of Burkholderia. The lysis cassette of these related phages has a similar organization (putative antiholin, putative holin, endolysin, and spanins) and shows 29–98 % homology between specific lysis genes, in contrast to Enterobacteria phage P2, the hallmark phage of this genus. The AP3 and KS5 lysis genes have conserved locations and high amino acid sequence similarity. The AP3 bacteriophage particles remain infective up to 5 h at pH 4–10 and are stable at 60 °C for 30 min, but are sensitive to chloroform, with no remaining infective particles after 24 h of treatment. AP3 lysogeny can occur by stable genomic integration and by pseudo-lysogeny. The lysogenic bacterial mutants did not exhibit any significant changes in virulence compared to wild-type host strain when tested in the Galleria mellonella moth wax model. Moreover, AP3 treatment of larvae infected with B. cenocepacia revealed a significant increase (P < 0.0001) in larvae survival in comparison to AP3-untreated infected larvae. AP3 showed robust lytic activity, as evidenced by its broad host range, the absence of increased virulence in lysogenic isolates, the lack of bacterial gene disruption conditioned by bacterial tRNA downstream integration site, and the absence of detected toxin sequences. These data suggest that the AP3 phage is a promising potent agent against bacteria belonging to the most common B. cenocepacia IIIA lineage strains.Electronic supplementary materialThe online version of this article (doi:10.1007/s00253-016-7924-7) contains supplementary material, which is available to authorized users.

Modular endolysin of Burkholderia AP3 phage has the largest lysozyme-like catalytic subunit discovered to date and no catalytic aspartate residue

“…Phage AP3, a representative of Gram-negatives infecting phages, utilizes a complex of four proteins which ensures efficient progeny release from an infected host cell. Its endolysin (AP3gp15), together with antiholin (AP3gp13), holin (AP3gp14) and bimolecular spanin (AP3gp16 and AP3gp17) form the lysis cassette 22 . AP3gp15 is a 266-amino acid protein with molecular mass of 28.9 kDa and theoretical pI of 8.82.…”

“…In this study, we present a comprehensive characterization of recombinant AP3gp15 endolysin encoded by the recently described phage AP3 (vB_BceM_AP3), specific to multidrug-resistant Burkholderia cenocepacia 22 . This modular endolysin is composed of CBD domain and EAD domain classified by BLAST into DUF3380 family.…”

Comparative Genomics of Environmental and Clinical Burkholderia cenocepacia Strains Closely Related to the Highly Transmissible Epidemic ET12 Lineage

“…The dramatic decline in the effectiveness of antibiotics has generated renewed interest in phage therapy ( Abedon et al, 2017 ). The use of bacteriophages as antibacterial therapeutics is especially important for targeting those pathogens for which antibiotic treatments are limited, e.g., in B. cenocepacia ( Lynch et al, 2013a ; Roszniowski et al, 2017 ). In this context, it is interesting to note that the absence of a self-defense CRISPR system makes these therapeutic approaches even more promising.…”

Galleria mellonella as a consolidated in vivo model hosts: New developments in antibacterial strategies and novel drug testing

“…Moreover, ceftazidimeavibactam was shown to improve the survival of larvae infected with extremely drug-resistant B. multivorans isolated from cystic fibrosis patients [50]. Besides antimicrobial drug combinations, the treatment of larvae infected with B. cenocepacia isolated from cystic fibrosis patients with Burkholderia phage AP3 revealed a significant increase in larvae survival in comparison to AP3-untreated infected larvae [51].…”