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Characterization and protective effects of lytic bacteriophage pAh6.2TG against a pathogenic multidrug-resistant Aeromonas hydrophila in Nile tilapia ( Oreochromis niloticus )
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  • Le Thanh Dien,
  • Le Buu Ky,
  • Bui The Huy,
  • Muhammad Fadhlullah Mursalim,
  • Pattanapon Kayansamruaj,
  • Saengchan Senapin,
  • Channarong Rodkhum,
  • Ha Dong
Le Thanh Dien
Chulalongkorn University Faculty of Veterinary Science
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Le Buu Ky
Truong Dai hoc Tien Giang
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Bui The Huy
Truong Dai hoc Tien Giang
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Muhammad Fadhlullah Mursalim
Chulalongkorn University Faculty of Veterinary Science
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Pattanapon Kayansamruaj
Kasetsart University Faculty of Fisheries
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Saengchan Senapin
National Center for Genetic Engineering and Biotechnology
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Channarong Rodkhum
Chulalongkorn University Faculty of Veterinary Science
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Ha Dong
Suan Sunandha Rajabhat University Faculty of Science and Technology
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Abstract

Bacteriophage is considered an alternative to antibiotics and environmentally friendly approach to tackle antimicrobial resistance (AMR) in aquaculture. Here, we reported isolation, morphology and genomic characterizations of a newly isolated lytic bacteriophage, designated pAh6.2TG. Host range and stability of pAh6.2TG in different environmental conditions, and protective efficacy against a pathogenic multidrug-resistant (MDR) Aeromonas hydrophila in Nile tilapia were subsequently evaluated. The results showed that pAh6.2TG is a member of the family Myoviridae which has genome size of 51,780 bp, encoding 65 putative open reading frames (ORFs), and is most closely related to Aeromonas phage PVN02 (99.33% nucleotide identity). The pAh6.2TG was highly specific to A. hydrophila and infected 83.3% tested strains of MDR A. hydrophila (10 out of 12) with relative stability at pH 7 ­ 9, temperature 0 ­ 40 °C and salinity 0 ­ 40 ppt. In experimental challenge, pAh6.2TG treatments significantly improved survivability of Nile tilapia exposed to a lethal dose of the pathogenic MDR A. hydrophila, with relative percent survival (RPS) of 73.3% and 50% for phage multiplicity of infection (MOI) 1.0 and 0.1, respectively. Significant reduction of bacterial counts in rearing water at 3 h (6.7 ± 0.5 to 18.1 ± 6.98 folds) and in fish liver at 48 h post-treatment (2.7 ± 0.24 to 34.08 ± 26.4 folds) was observed in phage treatment groups while opposite pattern for bacterial counts was observed in untreated control. Interestingly, the surviving fish provoked specific antibody (IgM) against the challenged A. hydrophila. These results might explain the higher survival in phage treatment groups. In summary, the findings suggested that the lytic bacteriophage pAh6.2TG is an effective alternative to antibiotics to control MDR A. hydrophila in tilapia and possibly other freshwater fish.

Peer review status:ACCEPTED

05 Jun 2021Submitted to Transboundary and Emerging Diseases
05 Jun 2021Submission Checks Completed
05 Jun 2021Assigned to Editor
14 Jun 2021Reviewer(s) Assigned
03 Jul 2021Review(s) Completed, Editorial Evaluation Pending
05 Jul 2021Editorial Decision: Revise Major
31 Jul 20211st Revision Received
31 Jul 2021Assigned to Editor
31 Jul 2021Submission Checks Completed
05 Aug 2021Reviewer(s) Assigned
09 Aug 2021Review(s) Completed, Editorial Evaluation Pending
10 Aug 2021Editorial Decision: Revise Minor
26 Aug 20212nd Revision Received
26 Aug 2021Submission Checks Completed
26 Aug 2021Assigned to Editor
03 Sep 2021Reviewer(s) Assigned
08 Sep 2021Review(s) Completed, Editorial Evaluation Pending
08 Sep 2021Editorial Decision: Accept