Ruckeri Infection Research Articles

Effect of mixed use of thyme and fennel oils on biochemical properties and electrolytes in rainbow trout as a response to Yersinia ruckeri infection

The aim of study was to compare the effects of supplementation of food with herbal oils (Thymus vulgaris and Foeniculum vulgare) on biochemical properties and electrolytes of rainbow trout infected with Yersinia ruckeri. In total, 120 healthy fish (mean weight 84 ± 1.02 g) were equally divided into four experimental groups. The experimental study was carried out for one week. The first group was control without supplementation and infection, the second group was infected and without oil supplementation, the third group was supplemented with oils (10 ml·100 g-1 rates) for one week and infected with Y. ruckeri and the last group was oil supplemented without infection. Results indicated that fish fed with dietary supplements showed enhanced bactericidal activity, total protein, albumin, cholesterol, triglyceride and bilirubin compared to the control (P < 0.05). As the value of herbal oils was increased in diets, the plasma glucose level decreased. The levels of K, Na, Ca, and Mg increased whereas Cl values decreased, compared to the control. It can be concluded that diet supplementation with herb oils used in this study can increase disease resistance by increasing levels of some biochemical parameters and electrolytes in rainbow trout to Y. ruckeri infection.

Gökkuşağı Alabalığı (Oncorhynchus mykiss Walbaum 1792) Çiftliklerinde Yersinia ruckeri İnfeksiyonunun Bakteriyolojik Kültür ve Polimeraz Zincir Reaksiyonu (PCR) ile İncelenmesi

Summary This study has been carried out to investigate the presence of Yersinia ruckeri, the causative agent of Enteric Red Mouth (ERM) disease, in rainbow trout fish breeding farms located in Elazig and Malatya provinces in Eastern Turkey. For this purpose, bacteriological culture and a specific polymerase chain reaction (PCR) have been compare with examine blood and intestine samples collected from adult and young rainbow trout fish as well as water samples collected from all the farms. Y. ruckeri was isolated and identified from eight of the 17 fish farms giving a proportion of 52.9% at fish farm. The disease was noted in five of the rainbow trout farms located in Elazig and three of the 11 rainbow trout farms located in Malatya. The agent was detected in five of the six young fish breeding farms. The isolation percentages of the causative agent at fish level were calculated as 25.7% (131/510) in adult and 31.7% (19/60) in young fish, giving an overall proportion of 26.3% (150/570). All the isolates have been successfully identified as Y. ruckeri by species-specific PCR. No isolation could be made from water samples. It is therefore concluded that Y. ruckeri infection poses a significant threat to the fish farms in the study area and necessary precautions should urgently be taken in order to minimize economical losses due to ERM disease. A specific PCR can be utilized successfully in aquaculture for rapid identification of bacterial agents which will help to prevent spread of infectious diseases and will therefore contribute to the productivity of fishery sector.

Sequencing of a second interleukin-10 gene in rainbow trout Oncorhynchus mykiss and comparative investigation of the expression and modulation of the paralogues in vitro and in vivo

Interleukin-10 (IL-10) is a multifaceted cytokine that is produced by and effects a variety of cell populations, including macrophages, T, B and NK cells. The gene encoding for IL-10 has been isolated in mammals, birds, amphibians and recently in fish, with only single copy identified in each species. We report here a second IL-10 gene (tIL-10b) in rainbow trout that showed 92% identity in the coding region but only 50% identity in the 5′- and 3′-UTR to the known trout IL-10 paralogue, which we have now called tIL-10a. There is a short upstream open reading frame (uORF) within the 5′-untranslated region (UTR) of tIL-10a that may inhibit its translation, whilst in tIL-10b multiple mRNA instability motifs exist in the 3′-UTR, suggesting that the two IL-10 paralogues may have different mechanisms to regulate their expression post-transcriptionally. The expression of tIL-10a is generally higher than that of tIL-10b in most of the fourteen tissues examined and in the RTS-11, RTL and RTGill cell lines. However, the expression level of tIL-10b can exceed that of tIL-10a, as seen in vivo in the ovary of healthy fish and in the gills of Yersinia ruckeri challenged fish, and in vitro in head kidney (HK) leucocytes cultured for ≥8 h. The expression of the trout IL-10 paralogues can be up-regulated by LPS and polyIC in RTS-11 cells and by LPS, polyIC, PHA, PMA, calcium ionophore (CI) and IL-21 in head kidney leucocytes, as well as by Y. ruckeri infection, and can be modulated positively or negatively by IFN-γ. Synergistic effects on up-regulation of IL-10 expression were also seen between PHA and IL-21, as well as between PMA and CI. The expression kinetics of the IL-10 paralogues was also found to be different, suggesting that rainbow trout has evolved different pathways to regulate the expression of the two IL-10 paralogues at the transcriptional level.

Temporal and pathogen-load dependent changes in rainbow trout ( Oncorhynchus mykiss) immune response traits following challenge with biotype 2 Yersinia ruckeri

Rainbow trout infected with Yersinia ruckeri, the causative agent of enteric redmouth disease (ERM), produce a pro-inflammatory and acute-phase response attributed in part to the innate recognition of bacterial-produced flagellin. Recently, variants of Y. ruckeri have been identified that lack flagella and associated motility. These strains are classified as biotype 2 (BT2) Y. ruckeri and these are considered an emerging problem in salmonid aquaculture. Little is known about the salmonid immune response to these variants. Herein, we report temporal and quantitative changes in rainbow trout immune response parameters following a primary challenge with BT2 Y. ruckeri strain YRNC10. Fish were injection-challenged with ten-fold dilutions of viable bacteria and sampled on days 1, 3, 5 and 7 post-challenge. TNFα1 and IL1-β1 transcripts were increased by day 1 post-challenge, and on days 3, 5 and 7 maximal gene transcript up-regulation occurred at a threshold of ∼64–256 CFU per mg spleen tissue. Infection induced robust SAA gene up-regulation that was significantly correlated with increased gene expression of IL-1β1 ( r = 0.81, P < 0.0001) and TNFα1 ( r = 0.55, P < 0.0001). Y. ruckeri infection induced modest changes in INFγ and Mx-1 gene transcript abundance at intermediate or high challenge doses and the expression patterns of both genes were positively correlated with pro-inflammatory gene and acute-phase gene transcription patterns. TNF superfamily 13b (BAFF) gene expression was significantly down-regulated in response to infection on days 3, 5 and 7 at the highest challenge doses. The spleen somatic index was significantly increased on days 3, 5 and 7 post-infection and positively correlated with spleen colony forming units and abundance of gene transcripts SAA, TNFα1, and IL1-β1. In summary, rainbow trout had a strong innate response following challenge with BT2 Y. ruckeri strain YRNC10 indicating that flagellin expression is not required for production of a robust pro-inflammatory and acute-phase gene transcription response. This study further supports the use of SAA transcript abundance and spleen somatic index as general measures of immunological status and fish health.

Yersinia ruckeri infection in cultured Nile tilapia, Oreochromis niloticus, at a semi-intensive fish farm in lower Egypt

A Yersinia ruckeri infection was recorded in 2007 among a group of Nile tilapia, Oreochromis niloticus, from an earthen pond at a semi-intensive fish farm in Sharkiya Province, lower Egypt. The outbreak took place during the late winter-spring transition period, effecting a total of 130 out of 150 fish, with a prevalence of 66.6%. The affected fish presented typical signs of yersiniosis, including extensive lip, mouth, fin and skin hemorrhages and hemorrhagic gastroenteritis, together with congestion of the internal organs. Tentative confirmation of the Yersinia ruckeri isolates was achieved using polymerase chain reaction (PCR), conventional biochemical assays and the API 20 E system. Mortalities were the result of a sharp fluctuation in water temperature, predation due to migratory birds that 'stopover' at this site, and to overstocking of ponds.

Experimental infection of brown trout, Salmo trutta L., using a Finnish Yersinia ruckeri isolate

The pathogenicity of a Finnish Yersinia ruckeri isolate to 1-year-old brown trout was tested using both immersion and injection mode of infection. The occurrence of bacteria and antibody production were monitored for up to 25 days. No disease signs or mortality due to Y. ruckeri occurred in the immersion experiment where the fish were further stressed with Ichthyophthirius multifiliis, but Y. ruckeri was isolated from certain organs in half of the fish. The intestine, kidney and spleen were the most favoured sites of infection, only one fish having bacteria in the liver. The injection of brown trout caused 100% Y. ruckeri infection and some mortality was recorded during the first week post infection. All dead fish exhibited signs of bacterial infection but none had inflammation around the mouth. Antibodies against Y. ruckeri were produced in both the groups subjected to immersion and that subjected to injection but the production was higher in the injected fish. These results confirm earlier findings that the Finnish Y. ruckeri is less pathogenic than, for example, Y. ruckeri in USA, and indicate that more experimental studies are needed to examine the significance of geographical variation of Y. ruckeri strains in terms of their pathogenicity.

Occurrence of Yersinia ruckeri infection in farmed whitefish, Coregonus peled Gmelin and Coregonus muksun Pallas, and Atlantic salmon, Salmo salar L., in northern Finland

Yersinia ruckeri, the aetiological agent of enteric redmouth disease (ERM), is now generally recognized to be distributed worldwide. The pathology and epizootiology of the disease was first described by Rucker (1966) and although rainbow trout, Salmo gairdneri Richardson, has been the most frequently affected species, all salmonids are now considered to be potential hosts for the organism (McDaniel 1979). The present paper reports the first confirmed occurrence of Y. ruckeri infection in farmed whitefish and Atlantic salmon, Salmo salar L., in Finland, with the known host range being extended to include the whitefish Coregonus peled Gmelin and Coregonus muksun Pallas . The outbreaks of infection involved two fish farms on the Oulujoki and Iijoki rivers in northern Finland (Fig. 1). Infection in whitefish Yersinia ruckeri infection was first identified in July 1982 in a mixed population of 3500 C. peled and C. muksun broodstock fish held in a single 1000-m 2 earthen pond at farm A. The organism was isolated from only one of four diseased C. muksun examined bacteriologically at this time and mortalities during the summer months were light (0 .5-1 .0%) for both species. The following year Y. ruckeri was isolated from the internal organs of both C. peled and-C. muksun on a number of occasions during the period from June to August, but again mortalities remained at a low level (0 .5—F5%) throughout. In 1984 infection was confirmed in C. peled but not C. muksun broodstock (Fig. 2). The low levels of mortality associated with the Y. ruckeri infection are similar to those recorded for diseased brook trout, Salvelinus fontinalis (Mitchill), and landlocked Atlantic salmon in Australia where a Y. ruckeri-like organism was isolated (Llewellyn 1980) and in an ERM outbreak in rainbow trout in Canada (Wobeser 1973). Diseased whitefish showed loss of scales, haemorrhages on the body surface and paired fin bases, and petechiation in the peritoneum and visceral fat. Some affected fish. also exhibited severe inflammation of the distal portion of the intestine and vent. Saprolegnia