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The distribution of different phenotypes of the complement component C3 and a possible correlation with body weight were investigated in five Danish strains (A, C, D, E, J) of farmed trout (Oncorhynchus mykiss Walbaum). All strains showed the presence of the f1 and f2 alleles; two of these strains also expressed the s allele. Most common was the f1 allele (> 68%); rarest was the s allele (

Summary A sanitation programme for stamping-out viral haemorrhagic septicaemia (VHS) was implemented in Denmark in 1965. The programme has resulted in a dramatic reduction in the number of infected rainbow trout farms, from 5400 to 26. The programme is carried out on a voluntary basis at the expense of the involved fish farm owners. The fact that financial support for the eradication of VHS and IHN may be made available from the European Union may enhance the efforts towards further eradication of the disease in Europe. The finding of a VHS virus (VHSV)-like virus in the marine environment is a matter of major concern, but improved diagnostic procedures may enable discrimination between the highly pathogenic freshwater strains and the apparently less virulent marine strains.

Summary An ELISA for rapid detection of viral haemorrhagic septicaemia virus (VHSV, Egtved virus) in fish tissue was developed and tested with regard to sensitivity. The test is a valuable addition to traditional isolation of VHSV in cell culture when a rapid diagnosis is needed.

Summary An enzmelinked immunosorbent assay was developed for detection of antibodies in rainbow troui (Oncorhus mykiss) to Yersinia ruckeri, the causative agent of enteric redmouth disease. The test proved to be more sensitive than the agglutination test, but still allowed detection of antibodies in only a very small percentage of immersion-vaccinated trout. In passive immunization studies it was shown that humoral factors may play a significant role in protective immunity after immersion vaccination with Yersinia ruckeri bacterins. Zusammenfassung ELISA-Test und passiver Immunisierungstest fur den Nachweis von Antikorpern bei Regenbogenforel-len nach Immersionsvakzinierung mit einer Yersinia ruckeri Bakterine Es wurde ein ELISA-Test fur den Nachweis von Antikorpern gegen Yersinia ruckeri—dem ursachlichen Erreger der „Rotmaulseuche” (Enteric Redmouth Disease/ERM)-in Regnbogenforellen (Oncorhynchus mykiss) entwickelt. Die Methode erwies sich empfindlicher als die bisher verwendete Agglutina-tionsmethode, aber gestattete den Nachweis von Antikorpern bei immersionsvakzinierten Forellen in einem nur gerinr Prozentsatz. Versuche mit passiver Immunisierung zeigten, das humorale Faktoren eine wahrscheinich signifikante Rolle beim Immunschutz der Fische nach Immersionsvakzinierung mit Yersinia ruckeri Bakterinen spielen. Reesume ELISA et transferement passive d'immunite pour la dimonstration de la response d'anticorps chez la truite arc-en-ciel apres vaccination par immersion Un test immunoenzymatiues du type ELISA a ete develope pour dttecter des anticorps de la truite arc-en-ciel contre Yersinia ruckeri. Le test a ete affirme plus sensible que l'epreuve d'aggutinatlon drrecte mais il permet toujour uniquement la detection d'anticorps dans tres peu de truites vaccinees par immersion. Par l'immunisation passive de truitelles, il a ete demontre que des facteurs humorales joue un role significatif dam l'immunite protective apres vaccination par immersion contre la yersiniose.

Summary The humoral immune response of trout to Egtved virus (VHS) was examined by means of a 50 % plaque neutralization test with complement addition. The test, wich has been adapted for use in microtitre plates, is documented with regard to specificity and sensitivity. Eight weeks after VHS infection by cohabitation at 13 °C neutralizing antibody could be detected in 100% of individually tagged experimental trout. Maximal litres of 10240 were found six weeks after infection. In 36% of the trout antibody was still detectable one year after infection. Neutralizing antibody could be detected also in trout infected with VHS under trout farm conditions. The percentage of positive sera ranged from 4 to 56.

Summary Two Egtved virus strains have been isolated from sick rainbow trout (Salmo gairdneri). One isolate (49/82) could not be neutralized using VHS (F1) rabbit amiserum, whereas the other one (67/82) could be neutralized at a low titre. The isolates were identified by means of IFAT and they possess low virulence to adult rainbow trout (80 g). Zusammenfassung Egtved Virus: Das Vorkommen von Stammen, die nicbt eindeutig mittels des Neutralisationstestes zu identifizieren sind Von erkrankten Regenbogenforellen (Salmo gairdneri) konnten 2 VHS-Stamme isoliert warden. Eines der Isolate (49/82) wurde durch VHS (F1) Kaninchenantiserum nicht, das andere Isolat (67/82) nur schwach neutralisiert. Mit der IFAT konnten die Isolate jedoch eindeutig identifiziert werden. Die Isolate zeigten eine geringe Virulenz fur adulte Regenbogenforellen (80 g). Resume Virus Egtved: Apparition de souches qui ne sont pas clairement identifiables par le test de neutralisation Deux souches de VHS ont ete isolees de unites arc-en-ciel (Salmo gairdneri) malades. Une des souches (49/82) n'a pas ete neutralisee par l'antiserum de lapin VHS (F1), l'autre (67/82) ne fut que faiblement neutraiisee. Les deux souches ont cependant pu etre identifiees avec l'IFAT. Les souches ont montre une faible virulence chez les truites arc-en-ciel adultes (80 g).

Summary A rhabdovirus has been isolated from snakehead (Ophicephalus striatus) in Thailand showing an ulcerative syndrome. The virus did not exhibit any serological relationship to VHSV, IHNV, RVC, PFRV or EVX. Zusammenfassung Serologische Untersuchung eines Rhahdovirusisolates vom Schlangenkopffisch (Ophicephalus striatus) mit ulcerativem Syndrom in Thailand Von einem Schlangenkopffisch (Ophicephalus striatus) mit dem ulcerativem Syndrom wurde ein Rhabdovirus in Thailand isoliert, das keine serologische Verwandtschaft zu VHSV, IHNV, RVC, PFRV und EVX aufweist. Resume Examen serologique d'un rhabdovirus isole de Ophicephalus striatus avec syndrome ulceratif en Thailande En Thailande un rhabdivirus a ete isole de Ophicephalus striatus montrant un syndrome ulceratif. Le virus ne montrait aucune relation serologique avec VHSV, IHNV, RVC, PFRV ou EVX.