Isolation of a Vibrio sp., the causative bacterium of intestinal necrosis of Japanese flounder larvae.

119

The infection route of the inanne fish pathogen Vibrio anguillarum was studied after oral challenge of juvenile turbot Scophthalmus maximus L. through a live feed. Artemia nauplii were incubated In a suspension of V anguillarum cells, and subsequently fed twice to the fish. All challenged fish died within 4 d after the first challenge, whde no mortality occurred in the non-challenged controls The results of an immunohistochemical examination of the sectioned f~s h samples clearly demonstrated that V anguillarum cells were ingested by the Artemia and that the latter were ingested by the fish. Bacteria were released from the Arternia mainly In the anterior part of the intestine. Most challenged fish started to show disease slgns 24 h after the second challenge and died 2 d later. A histopathological analysis of monbund fish showed the development of septicaemia. Moreover, the sequential sampling, allowed the reconstruction of the infection route after oral challenge. Our results show that V anguillarum was transported through the intestinal epithelium by endocytosis, after which the bactenum was released in the lamina propna. From there the bactenum was transported by the blood to the different organs, eventually leading to septicaemia and mortality.

Section: Introductionmentioning

confidence: 99%

Mode of infection and spread of Vibrio anguillarum in turbot Scophthalmus maximus larvae after oral challenge through live feed

Grisez¹,

Sorgeloos²,

Ollevier³

1996

119

“…1990). These other variants have been traditionally considered to b e of no pathogenic significance, but have been also associated with disease in larval and adult stages of marine fish (Masumura et al 1989, Fouz e t al. 1990, Myhr e t al.…”

Section: Introductionmentioning

confidence: 99%

Pathogenicity studies on a Vibrio anguillarum-related (VAR) strain causing an epizootic in Argopecten purpuratus larvae cultured in Chile

Riquelme¹,

Hayashida²,

Ae³

et al. 1995

A Vibrio anguillarum-related (VAR) strain, isolated in pure culture from an epizootic in a commercial hatchery producing Argopecten purpuratus, was characterized, and its potential pathogenicity to veliger larvae of A. purpuratus determined. Experimental challenges indicated that the bacterium affects larval survival at concentrations of 104 to 108 cells ml-l The effect of water quality and temperature on pathogenicity was also evaluated. Larval survival in seawater filtered through 5 pm pore-size membranes was 45.6%, whereas using seawater passed through 1 and 0.2 pm filters, larval survival increased to 66.4 and 80.4 % respectively. Temperature also affected pathogenicity as larval survival at 15OC for 24 h was 69.3 % but decreased to 30 and 26.9 % at 20 and 25°C respectively. Toxic activity was found in cell-free supernatant of bacterial culture. Larval survival was reduced to 68.9 and 36.4% after 20 and 40% (v/v) of supernatant, respectively, was added to the rearing water. These results suggest that exotoxins produced by the VAR strain play an in~portant role in its pathogenicity for scallop larvae.

“…A group of larval flounder (20-d-old, 10.6 mm average total length) held at 20°C was given rotifers containing F-2, another virulent strain of Vibrio sp. INFL (Masumura et al 1989), for 3 consecutive days. After the first administration of the pathogen, 3 to 4 fish were collected at intervals of ca 12 h for 5 d. Fish samples, including control fish which were fed non-treated rotifers, were fixed in Eouin's solution, embedded in paraffin, sectioned at 5 pm, and stained with haematoxylin and eosin or methylene blue.…”

Section: Methodsmentioning

confidence: 99%

“…Bacteria isolated from different individuals of a given group were shown by the slide agglutination testusing a n antiserum against Vibrio sp. INFL (Masumura et al 1989) -to be identical to the administered pathogen. In contrast, no bacteria were observed on the mucosal surface of the intestine from non-infected fish (Fig.…”

Section: Histopathologymentioning

confidence: 99%

“…We subsequently characterized the pathogen in detail and tentatively named it Vibrio spp. INFL after the disease it causes: intestinal necrosis of flounder larvae (Masumura et al 1989). This disease was reproduced in larval flounder by oral administration of the pathogen incorporated into live food organisms, the rotifer Brachionus plicatilis and brine shrimp Artemia salina nauplii.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Bacterial enteritis of cultured flounder Paralichthys olivaceus larvae

Muroga¹,

Yasunobu²,

Okada³

et al. 1990

'Chokan-hakudaku-sho' is a devastating disease of larval Japanese flounder Paralichthys olivaceus caused by a bacterium tentatively named Vibrio sp. INFL after the disease it causes: intestinal necrosis of flounder larvae. The disease was reproduced in 16 to 27-d-old flounder larvae by oral challenge with Vibrio sp. INFL was incorporated into brine shrimp Arternia salina nauplii or rotifers Brachionus plicatilis, but not in older fish. Histopathological and electron microscopic examinations revealed that pathogen multiplication and resultant pathological changes occurred only in the intestine. Although pili-like structures were not observed on the cells of the pathogen, an adhesive property was demonstrated on a chinook salmon embryo (CHSE-214) cell line.