Issue |
Vet. Res.
Volume 34, Number 1, January-February 2003
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|
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Page(s) | 127 - 132 | |
DOI | https://doi.org/10.1051/vetres:2002057 | |
How to cite this article | Vet. Res. (2003) 127-132 |
DOI: 10.1051/vetres:2002057
Virulence stability in Flavobacterium psychrophilum after storage and preservation according to different procedures
Christian Michela and Céline Garciaba Institut National de Recherche Agronomique, Unité de Virologie et d'Immunologie Moléculaires, Centre de Recherches de Jouy-en-Josas, 78352 Jouy-en-Josas Cedex, France
b Institut Français de Recherche pour l'Exploitation de la Mer, Station de la Trinité, 12 rue des Résistants, BP 80, 56470 La Trinité-sur-Mer, France
(Received 16 May 2002; accepted 16 August 2002)
Abstract
Experimental infections and lethal dose 50% (LD
50) evaluation were conducted in
rainbow trout fingerlings, using a virulent strain of Flavobacterium psychrophilum
processed and stored or maintained in different ways; lyophilisation, freezing
at -80 °C, maintenance in enriched Anacker and Ordal (EAO) medium at 4 °C,
revival and subsequent in vivo passages in fish. Experiments were performed 1,
8 and 23 months after storing the bacteria. Out of a total of 12 cultures
revived for experimentation, one failed to grow and another was found to express
modified properties including decreased virulence in spite of in vivo passages.
In all other cases, whatever the conditions of preservation, virulence was
fairly well maintained after 1 and 8 months of storage. In the last test,
after 23 months, the bacteria maintained in the EAO medium at 4 °C were found
significantly attenuated. Conversely, lyophilised and frozen bacteria only
expressed a slight increase in LD
50. It was concluded that virulent strains
of F. psychrophilum were likely to retain their properties without special
provisions within limited periods of time, and that both lyophilisation
and freezing at -80 °C were reliable methods for long-term
preservation of virulence.
Key words: fish disease / bacteria / Flavobacterium psychrophilum / virulence / preservation
Correspondence and reprints: Christian Michel tel. (33) 1 34 65 25 86; fax: (33) 1 34 65 25 91;
e-mail: michel@jouy.inra.fr
© INRA, EDP Sciences 2003