Obiettivo The aim of the programme is to study the brown ring disease (BRD) of cultured clams (R. philippinarum and R. decussatus) which is due to a recently discovered pathogen, a Vibrio species called Vibrio P1. The programme must permit following the epidemiology of the BRD in France, Spain and Italy to: characterize pathogenic bacteria involved in BRD; analyze the relationship between bacteria and diseased clams; study the clinical symptoms and the pathogeny of the disease; improve bacteriological and immunological diagnostics; and adapt treatments to fight against the disease. Vibrio P1 will be improved on the other bivalve species of commercial value. A study was made of the 'brown ring disease' (BRD) of cultured clams (R philippinarum and R decussatus) which is due to a recently discovered pathogen, a Vibrio species called Vibrio P1. The bacteriological method for detecting the pathogen uses a selection system based on 4 key characteristics combined with a slide agglutination test using rabbit or rat antiserum. A protocol for VP1 detection by means of an enzyme linked immunosorbent assay (ELISA) test has also been developed. It is suggested that the pathogen belongs to the species V splendidus. This is in agreement with the conclusions of the ribosomal ribonucleic acid (rDNA) 16s sequence. Serological investigations showed that antigenic determinants of VP1 seem to be very specific and that weak cross reactions have only been recorded with vibrio species belonging to the group V pelagius V splendidus. Several potential virulence factors have been studied. The analysed strains show an haemolysin activity and a moderate hydrophobicity. The site of action of the pathogen in the hose has also been studied. The localization of the initial brown deposit development is correlated with local periostracal lamina disturbances. Direct infection of the sinusoperipheral compartment, even at low dose of VP1, gives the highest percentage of clams with BRD syndrome at the end of the experiment. For the first time, diseased clams of both species R philippinarum and R decussatus were found in Galicia and at a high prevalence. The disease is always present in Andalousia, but at low prevalences and none of the strains isolated were identified as VP1. Several Vibrio strains were isolated from diseased and healthy clams from South Spain. They were classified in groups to show an eventual correlation of 1 of the groups with BRD. Groups corresponding to V spendidus seemed to be more often present in diseased seed.The work will be carried out as follows. A standard diagnostic form will be established based on the examination of the symptoms of the brown disease at macroscopic and microscopic level. Bacteriological and immunological diagnostics will be compared for their efficiency and specificity. Characterization and origin of the pathogen will be realized by means of biochemical, sexological and genetical approaches on different isolates of Vibrio P1 originating from the different geographical areas which will be sampled by the participants. In the host pathogen interaction phase, the pathogeny of Vibrio P1 and the reactions of clams will be studied. In the epidemiology phase, a regular field control for monitoring the prevalence of the BRD in the culture zones will be carried out. A comparative study of the pathogenicity of the strains of Vibrio P1, isolated from different geographic localities, will be performed. Different strategies for treatment will be investigated. In the public health phase, the sanitary state of the diseased clams will be controlled. In fact, the weakness due to the BRD could lead to the proliferation of the human pathogenic opportunist germs such as Vibrio parahaemolyticus, Vibrio alginolyticus, Pseudomonas and Salmonella. Campo scientifico natural sciencesbiological sciencesmicrobiologybacteriologymedical and health scienceshealth sciencespublic healthepidemiologynatural sciencesbiological sciencesbiochemistrybiomoleculesproteinsenzymes Programma(i) FP2-FAR - Community research and coordination programmes (EEC) in the fisheries sector, 1988-1992 Argomento(i) Data not available Invito a presentare proposte Data not available Meccanismo di finanziamento Data not available Coordinatore Université de Bretagne Occidentale Contributo UE Nessun dato Indirizzo 6 avenue le Gorgeu 29287 Brest Francia Mostra sulla mappa Costo totale Nessun dato Partecipanti (5) Classifica in ordine alfabetico Classifica per Contributo UE Espandi tutto Riduci tutto CSIC-INST INVESTIGACIONES MARINAS-VIGO Spagna Contributo UE Nessun dato Indirizzo Vigo Mostra sulla mappa Costo totale Nessun dato Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) Francia Contributo UE Nessun dato Indirizzo Station de Nantes Rue de l'Ile d'Yeu 44037 Nantes Mostra sulla mappa Costo totale Nessun dato Istituto Zooprofilattico Sperimentale delle Venezie Italia Contributo UE Nessun dato Indirizzo Via G Orus 2 35129 Padova Mostra sulla mappa Costo totale Nessun dato UNIV MALAGA-FAC CIENCIAS-DEPT MICROBIOLOGIA Spagna Contributo UE Nessun dato Indirizzo Malaga Mostra sulla mappa Costo totale Nessun dato Università degli Studi di Siena Italia Contributo UE Nessun dato Indirizzo Via della Cerchia 3 53100 Siena Mostra sulla mappa Costo totale Nessun dato
