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Protective efficacy of phage PVN02 against haemorrhagic septicaemia in striped catfish Pangasianodon hypophthalmus via oral administration
Author(s) -
Dang Thi Hoang Oanh,
Xuan Tran T.T.,
Duyen Le T.M.,
Le Nga P.,
Hoang Hoang A.
Publication year - 2021
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/jfd.13387
Subject(s) - catfish , biology , aeromonas hydrophila , microbiology and biotechnology , phage therapy , veterinary medicine , bacteriophage , fishery , fish <actinopterygii> , medicine , escherichia coli , biochemistry , gene
Abstract Haemorrhagic septicaemia caused by Aeromonas hydrophila in striped catfish ( Pangasianodon hypophthalmus ) is one of the most important aquatic diseases in the Mekong Delta, Vietnam. However, antibiotic‐resistant A. hydrophila strains have become popular and resulted in inadequate control of the disease in striped catfish farms. This study investigates the protective efficacy of bacteriophage PVN02 against haemorrhagic septicaemia in striped catfish via oral administration. The phage‐containing pellets were prepared by spraying the phage solution on food pellets at 20 ml/kg. The rate of phage desorption from the food pellets into the water was very low; the phage titres in the water were approximately log 1.0 PFU/ml or undetectable. The in vivo experiment evaluating the protective efficacy of PVN02 against haemorrhagic septicaemia in striped catfish was conducted using 21 groups of 1,260 fish in 50‐L plastic tanks in triplicate. The catfish were fed twice daily with phage‐sprayed pellets. Different densities of bacterial suspensions were added into the tanks for 24 hr. Without the existence of the phage, the highest mortality rate was 68.3 ± 2.9% at the highest density of bacterial suspension. In contrast, the mortality rate at the highest density of bacterial suspension was significantly reduced to 8.33 ± 2.9% or 16.67 ± 2.9% at the phage dose of log 6.2 ± 0.09 or log 4.2 ± 0.09 PFU/g. This study provides a very practical manner of applying phage therapy to prevent disease in large‐scale striped catfish farms.