Emerging vesiculo-type virus infections of freshwater fishes in Europe.

Rhabdoviruses were isolated from perch Perca fluviatilis and largemouth bass Micropterus salmoides exhibiting clinical signs of disease. Preliminary studies indicated that these viruses could be neutralised by antisera to perch rhabdovirus (Dorson et al. 1984) and may be similar to those previously isolated from grayling Thymallus thymallus and pike-perch Stizostedion stizostedion.

Malacosporean-like spores in urine of rainbow trout react with antibody and DNA probes to Tetracapsuloides bryosalmonae.

Tetracapsuloides bryosalmonae is the myxozoan parasite causing proliferative kidney disease (PKD) of salmonid fishes in Europe and North America. The complete life cycle of the parasite remains unknown despite recent discoveries that the stages infectious for fish develop in freshwater bryozoans. During the course of examinations of the urine of rainbow trout (Oncorhynchus mykiss) with or recovering from PKD we identified spores with features similar to those of T.

Phylogenetic analysis of viral haemorrhagic septicaemia virus (VHSV) isolates from France (1971-1999).

The nucleotide sequences of a specific region of the glycoprotein gene were compared among 63 strains of viral haemorrhagic septicaemia virus (VHSV) isolated from fish in France between 1971 and 1999. The analysis was performed on a region corresponding to amino acids 238 to 331 of the glycoprotein gene, also designated the V2 region and previously shown to accumulate most of the mutations. The sequences of many VHSV isolates were found to be identical or very conserved.

Sea bream Sparus aurata, an asymptomatic contagious fish host for nodavirus.

During an epidemiological survey of viral encephalopathy and retinopathy (VER) in diseased sea bass Dicentrarchus labrax, a nodavirus isolate was recovered from net pen-reared sea bream Sparus aurata harboured in the same farming premises. After the virus was isolated and identified by immunofluorescence on SSN-1 cells, sequence analysis with a PCR product from the T4 region of the capsid protein gene indicated that the virus shared 100% identity with a pathogenic virus strain isolated from sea bass. Infection trials demonstrated the pathogenicity of the sea bream virus isolate for juvenile sea bass whereas sea bream infected with the same virus isolate remained asymptomatic even following intramuscular injection of virus.

Evidence that infectious stages of Tetracapsula bryosalmonae for rainbow trout Oncorhynchus mykiss are present throughout the year.

Proliferative kidney disease (PKD) is a hyperplastic condition of the lymphoid tissue of salmonids infected with the spores of Tetracapsula bryosalmonae, a myxozoan parasite formerly designated PKX, which has recently been described as a parasite of several species of bryozoans. The occurrence of PKD is generally associated with seasonal increase in water temperature, with research indicating that transmission of the disease does not occur below 12 to 13 degrees C. This suggested that the infectious stages are absent from about November to March/April.