Bacteriophage control of Pseudomonas plecoglossicida infection in ayu.

Park Se Chang

Nakai Toshihiro

Diseases of Aquatic Organisms

Two previously isolated phages were used to examine the therapeutic effects against Pseudomonas plecoglossicida infection in ayu Plecoglossus altivelis. Phage PPp-W4 (Podoviridae) inhibited the in vitro growth of P. plecoglossicida more effectively than Phage PPpW-3 (Myoviridae), and a mixture (PPpW-3/W-4) of the 2 phages exhibited the highest inhibitory activity. In phage therapy experiments, ayu were fed P. plecoglossicida-impregnated feed (107 CFU fish-1) and then fed phage-impregnated feed (107 PFU fish-1). Mortalities of fish receiving PPpW-3, PPpW-4, PPpW-3/W-4, and a control fish receiving no phages were 53.3, 40.0, 20.0 and 93.3%, respectively. Phage (PPpW-3/W-4)-receiving fish also showed high protection against water-borne infection with P. plecoglossicida. In a field trial, when phage (PPpW-3/W-4)-impregnated feed was administered to ayu in a pond where the disease occurred naturally, daily mortality of fish decreased at a constant level (5% d-1) to one-third after a 2 wk period. The causal relationship of phages in this phenomenon was verified by the long-lasting appearance of administered phages in the kidneys of the fish, and a disappearance of P. plecoglossicida from apparently healthy fish. Neither phage-resistant organisms nor phage-neutralizing antibodies were detected in diseased fish or apparently healthy fish, respectively. These results indicate the potential for phage control of the disease.

Bacteriophage

Phage therapy

Fish disease

Biological control

Pseudomonas plecoglossicida

Plecoglossus altivelis

Zoology [ 480 ]

eng

Inter-Research

Copyright (c) 2003 Inter-Research.

[ISSN] 0177-5103

[ISSN] 1616-1580

[DOI] 10.3354/dao053033

[NCID] AA10443976

[DOI] http://dx.doi.org/10.3354/dao053033