Association of mycobacteria in recirculating aquaculture systems and mycobacterial disease in fish

Mycobacterium marinum isolates cultivated from tissue containing granulomatous lesions in Florida pompano Trachinotus carolinus and from biofilm samples collected from their tank and water recirculating system had identical (L1 of 11 bands) repetitive-sequence-based polymerase chain reaction (rep-PCR) DNA fingerprints. A second M. marinum clone sharing 4 of 11 rep-PCR bands with the first clone was isolated from some fish tissues but not from system samples. Water samples yielded low numbers of colonies of mycobacteria (0.08-1.3/mL), but high numbers were recovered from biofilms (260-12,000/swab) and filters (63-21,000/ filter). Mycobacterium hemophilum, M. chelonae, M. trivale, M. gastri, and M. gordonae were isolated from system samples alone.     

Cytokine responses of Holstein and Sahiwal zebu derived monocytes after mycobacterial infection

Recently, we found that Holstein cattle (Bos taurus taurus) displayed higher skin test prevalence and disease severity compared to zebu (Bos taurus indicus) herd-mates kept under identical husbandry conditions in Ethiopia. To determine whether these susceptibility differences were patent at the level of the innate immune system, we infected monocytes from naïve Holstein or Sahiwal zebu cattle with either live virulent Mycobacterium tuberculosis or Mycobacterium bovis. The cytokine profile following infection was compared between the two breeds by measuring IL-1α, IL-6, IL-10, IL-12 and TNF-α as well as nitric oxide in culture supernatants. Our results suggested subtle differences in the cytokine profile because only infection-induced IL-6 production was significantly increased in monocytes from the more susceptible Holstein cattle.     

Comparative immunological and microbiological aspects of paratuberculosis as a model mycobacterial infection

Paratuberculosis or Johne's disease of livestock, which is caused by Mycobacterium avium subsp. paratuberculosis (MAP), has increased in prevalence and expanded in geographic and host ranges over about 100 years. The slow and progressive spread of MAP reflects its substantial adaptation to its hosts, the technical limitations of diagnosis, the lack of practical therapeutic approaches, the lack of a vaccine that prevents transmission and the complexity and difficulty of the on-farm control strategies needed to prevent infection. More recently evidence has accumulated for an association of MAP with Crohn's disease in humans, adding to the pressure on animal health authorities to take precautions by controlling paratuberculosis. Mycobacterial infections invoke complex immune responses but the essential determinants of virulence and pathogenesis are far from clear. In this review we compare the features of major diseases in humans and animals that are caused by the pathogenic mycobacteria M. ulcerans, M. avium subsp. avium, M. leprae, M. tuberculosis and MAP. We seek to answer key questions: are the common mycobacterial infections of humans and animals useful "models" for each other, or are the differences between them too great to enable meaningful extrapolation? To simplify this, the immunopathogenesis of mycobacterial infections will be defined at cellular, tissue, animal and population levels and the key events at each level will be discussed. Many pathogenic processes are similar between divergent mycobacterial diseases, and at variance between virulent and avirulent isolates of mycobacteria, suggesting that the research on the pathogenesis of one mycobacterial disease will be informative for the others.     

Contribution to our knowledge of the physiology and metabolism of endurance horses

The functional and metabolic processes of the endurance horse are discussed, based on personal experience and the scientific literature. Research on the energetic and physiological aspects of prolonged effort is reviewed, as regards the performance structure, described by Neumann, for human physiology.Experimental data from our previous surveys on endurance horses, competing at different levels, are also presented and discussed.The results on amino acid levels in blood, and related metabolic pathways, during endurance events, lead to speculation on the effects of the race distance on metabolic processes during long-lasting low-intensity exercise. In fact, the event distance has a significant influence on amino acid mobilization and their use as energy sources. In human athletes, the disappearance of some amino acids from blood circulation is linked to the onset of central fatigue. The effect could be similar in endurance horses; therefore, the correct intake of amino acids, and a proper feeding strategy, could improve performance.Data are also provided on dehydration and oxidative stress associated with endurance work.     

Anisakidae infection in fish of the Aegean Sea

Nematode worms of the family Anisakidae are the causative agents of infections in humans when fish is consumed raw and of serious allergies up to the death, when fish is consumed raw or cooked by previously sensitized people. From April until November 2009, 462 fish belonging to 26 species, fished in three areas of the Aegean Sea were tested for Anisakidae larvae. Anisakidae larvae were detected in 87 (18.83%) fish of 13 species. These larvae were identified by morphology as the third-stage larvae of the genera Hysterothylacium sp. or Anisakis. Larvae of the genus Anisakis were identified by PCR-RFLP as belonging to A. simplex s.str., A. pegreffii, or as hybrids between A. simplex s.str and A. pegreffii.     

鱼类的核苷酸营养：研究现状及应用展望（续完）

上期回顾：上一期本刊编辑首先提出向畜牧生产推荐此文的目的,随后简要介绍了核苷酸在动物和水产动物营养上的总体研究概况,并提出了有必要对其在水产动物营养上所起作用进行总结和评估的重要性,最后比较详细地介绍了核苷酸的生物化学特征、水产动物对核苷酸及相关代谢产物的消化和吸收和核苷酸对水产动物化学诱食的作用。     

Ante mortem diagnosis of mycobacterial infection by liver biopsy in a budgerigar (Melopsittacus undulatus)

Avian mycobacteriosis is an important disease which affects exotic, wild and domestic birds. The disease is most commonly caused by the ubiquitous soil and water organisms Mycobacterium avium sp. avium and Mycobacterium genavense. Mycobacteriosis should be considered in the differential diagnosis of any pet bird with chronic disease characterized by weight loss, an inflammatory leukogram and abdominal enlargement.Ante mortem diagnosis of avian mycobacteriosis in birds remains difficult. The present case report describes that even in very small species such as a budgerigar the investigating of a biopsy sample is an efficient way to rule out or confirm the disease in cases where other methods fail to be conclusive.     

Recent advances in our knowledge of Mycobacterium bovis: a feeling for the organism

Significant and rapid progress has been made in our knowledge and understanding of Mycobacterium bovis since the last international M. bovis conference 5 years ago. Much of this progress has been underpinned by the completion of the genome sequence. This important milestone has catalysed research into the development of a number of improved tools with which to combat bovine tuberculosis. In this article we will review recent progress made in the development of these tools and in our understanding of the organism, its evolution and spread. Comparison of the genome sequence with those of other members of the Mycobacterium tuberculosis complex has enabled insights into the evolution of M. bovis. This analysis also indicates that the M. tuberculosis complex have the propensity to adapt to new host species. The use of high throughput molecular typing methods has revealed that the recent bovine tuberculosis epidemic in Great Britain is being driven by a number of clonal expansions, which cannot be explained by random mutation and drift alone. Completion of a number of mycobacterial genome sequences has allowed the development of antigen mining techniques that rapidly identify M. bovis-specific genes. These can then be used as reagents in the gamma interferon assay to increase the specificity of the assay and also to discriminate between Bacillus of Calmette and Guérin (BCG) vaccinated animals and those infected with M. bovis. In the longer term, comparisons between the genomes of M. bovis and BCG will allow insight into how BCG became attenuated following serial passage on artificial growth media and reveal clues into how to improve the vaccine efficacy of BCG.     

How molecular methods change our views of FeLV infection and vaccination

FeLV was discovered 40 years ago and vaccines have been commercially available for almost two decades. So far, most FeLV pathogenesis and vaccine studies were conducted assaying parameters, such as virus isolation and antigen detection. Accordingly, regressive infection was characterized by transient or undetectable viremia, while persistent viremia is typically observed in cats with progressive infection. Using real-time polymerase chain reaction assays, the spectrum of host response categories to FeLV infection was recently refined by investigating proviral and plasma viral RNA loads. Cats believed to be immune to FeLV infection were found to turn provirus-positive after virus exposure. Moreover, efficacious FeLV vaccines were found unable to prevent provirus-integration and minimal viral replication. Remarkably, no difference was found in initial proviral and plasma viral RNA loads between cats with different infection outcomes. Only subsequently, the infection outcome is associated with FeLV loads. FeLV provirus was found to persist for years; reoccurrence of viremia and disease development was observed in some cats. Thus, aviremic provirus-positive cats are FeLV carriers and, following reactivation, may act as an infection source. However, integrated viral DNA may also be essential for solid protection and long-lasting maintenance of protective immunity. In conclusion, real-time TaqMan PCR and RT-PCR assays are highly sensitive and specific. They yield a more sensitive measure for FeLV exposure than antigen detection, virus isolation or immunofluoresence assays. We recommend the use of real-time PCR assays to identify FeLV exposed cats, particularly in catteries, and investigate obscure clinical cases that may be FeLV-associated. The use of sensitive molecular methods will contribute to a more in-depth understanding of the FeLV pathogenesis.     

Maedi-Visna virus infection in sheep. History and present knowledge

Briefly the history of maedi-visna and the major clinical symptoms are described. Examples are presented to demonstrate that the genetic composition of a breed determines whether or not sheep become sick after an infection with maedi-visna virus (mvv) or develop solely specific antibodies. The major pathway of transmission is not colostrum and milk, but a cell containing increased nasal discharge in cases of respiratory distress. The role of the environment and prophylactic measures against parasites is stressed, because even sheep of highly susceptible breeds can survive an infection under optimal conditions. The virus and subsequently the disease simply die out. The cooperation between clinicians and laboratories is necessary.     

Nematode infection in fish from Cartagena Bay, North of Colombia

Parasitic nematode infection indices were recorded in different fish species collected at Cartagena Bay, North of Colombia. Among 19 studied species, the Mugil genus presented the highest prevalence (83.9-100%), although Sciades herzbergii, Caranx hippos and Centropomus undecimalis were also found infected with nematodes. Parasites were found in the liver, intestinal mesenteries and encysted near the intervertebral joints, with an average parasite abundance of 4.0 ± 0.3 nematodes per fish. Morphological analysis allowed the identification of these nematodes as Contracaecum sp. A small, but positive correlation was found between parasite abundance and length (R=0.294, P<0.001) and weight (R=0.244, P<0.001). In contrast, the correlation between parasite abundance and condition factor was negative (R=-0.191, P<0.001). These results are the first describing the presence of nematodes in several fish species of this ecosystem, and it highlights the need for monitoring parasitism in Mugil species in order to avoid parasite ingestion during fish consumption.     

Anisakidae larval infection in fish fillets sold in Belgium.

Fish fillets (n = 1760) sold on the Belgium market were examined for Anisakidae larval infection. Seven sea fish species were examined by means of the candling technique over a period of 4 months, from November 1996 to February 1997. Third-stage larvae of Anisakis simplex and Pseudoterranova decipiens were identified. A. simplex was the most abundant species with a prevalence of 84.5%, and was found in 192 of the examined fillets (10.9%). Pollock (Pollachius pollachius) was the most heavily infected fish species (82.9%). The prevalence in cod (Gadus morhua), saithe (Pollachius virens), and whiting (Merlangius merlangus) was 34.7%, 26.7%, and 15.4% respectively. The prevalence in the three other fish species examined was low, namely 8.9%, 6.6%, and 3.8% for ling (Molva molva), catfish (Anarchias lupus), and Northeast red fish (Sebastes marinus), respectively. Pollock was the fish species with the largest number of Anisakis larvae (7.8 larvae/kg fish fillet).     

Pathogenesis of and strategies for preventing Edwardsiella tarda infection in fish

Edwardsiella tarda is one of the serious fish pathogens, infecting both cultured and wild fish species. Research on edwardsiellosis has revealed that E. tarda has a broad host range and geographic distribution, and contains important virulence factors that enhance bacterial survival and pathogenesis in hosts. Although recent progress in edwardsiellosis research has enabled the development of numerous, highly effective vaccine candidates, these efforts have not been translated into a commercialized vaccine. The present review aims to provide an overview of the identification, pathology, diagnosis and virulence factors of E. tarda in fish, and describe recent strategies for developing vaccines against edwardsiellosis. The hope is that this presentation will be useful not only from the standpoint of understanding the pathogenesis of E. tarda, but also from the perspective of facilitating the development of effective vaccines.