Identification of new antigen candidates for the early diagnosis of Mycobacterium avium subsp. paratuberculosis infection in goats

Interferon-γ Response of Mycobacterium avium subsp. paratuberculosis Infected Goats to Recombinant and Synthetic Mycobacterial Antigens

Despite its potential for early diagnosis of Mycobacterium avium subsp. paratuberculosis (MAP) infection, the IFN-γ release assay is not used routinely, because of low specificity of the established crude antigen preparation Johnin (PPDj). Limited data are available assessing the potential of MAP-derived protein and lipopeptide antigens to replace PPDj in assays for goats, while cattle and sheep have been studied more extensively. Furthermore, MAP infection is claimed to interfere with the diagnosis of bovine tuberculosis when other crude antigen preparations (PPDb, PPDa) are applied. In this study, the diagnostic potential of MAP-derived recombinant protein antigens, synthetic MAP lipopentapeptides and of Mycobacterium bovis-specific peptide cocktails was assessed compared to crude mycobacterial antigen preparations in experimentally infected goats. Goats were inoculated with MAP, or Mycobacterium avium subsp. hominissuis (MAH) as surrogate for environmental mycobacteria, non-exposed animals served as controls. Mycobacterium avium Complex-specific antibody and PPDj-induced IFN-γ responses were monitored in vivo. Infection status was assessed by pathomorphological findings and bacteriological tissue culture at necropsy 1 year after inoculation. The IFN-γ response to 13 recombinant protein antigens of MAP, two synthetic MAP lipopentapeptides and three recombinant peptide cocktails of Mycobacterium bovis was investigated at three defined time points after infection. At necropsy, MAP or MAH infection was confirmed in all inoculated goats, no signs of infection were found in the controls. Antibody formation was first detected 3-6 weeks post infection (wpi) in MAH-inoculated and 11-14 wpi in the MAP-inoculated goats. Maximum PPDj-induced IFN-γ levels in MAH and MAP exposed animals were recorded 3-6 and 23-26 wpi, respectively. Positive responses continued with large individual variation. Antigens Map 0210c, Map 1693c, Map 2020, Map 3651cT(it), and Map 3651c stimulated increased whole blood IFN-γ levels in several MAP-inoculated goats compared to MAH inoculated and control animals. These IFN-γ levels correlated with the intensity of the PPDj-induced responses. The two synthetic lipopentapeptides and the other MAP-derived protein antigens had no discriminatory potential. Stimulation with Mycobacterium bovis peptide cocktails ESAT6-CFP10, Rv3020c, and Rv3615c did not elicit IFN-γ production. Further work is required to investigate if test sensitivity will increase when mixtures of the MAP-derived protein antigens are applied.

Mycobacterium Avium Paratuberculosis: A Disease Burden on the Dairy Industry

Mycobacterium avium paratuberculosis is responsible for paratuberculosis or Johne's disease in cows, having economic impacts on the dairy industry and a prevalence rate exceeding 50% in dairy herds. The economic burden of Johne's disease relates to decreased milk production and costs of disease prevention, treatment, and management, while having an economic impact on dairy producers, processors, consumers, and stakeholders of the dairy industry. Determining the true economic impact of the disease is difficult at regional and farm level as symptoms are not evident in subclinically infected animals. At present, the virulence, pathogenicity, persistence, and infectious dose of M. avium paratuberculosis are poorly understood, consequently effective paratuberculosis control measures remain obscure. M. avium paratuberculosis is potentially zoonotic with foodborne transmission a public health risk due to a possible causative link with inflammatory bowel disease in humans. A preventive approach is necessary to reduce the presence of this drug-resistant pathogen in dairy herds and subsequently dairy food. The use of inefficient diagnostic tests coupled with the long latency period of infection results in delayed animal culling and trade of asymptomatic animals, leading to regional transmission and increased disease prevalence. To date, there has been limited success at controlling and treating this terminal endemic disease, leading to significant prevalence rates. This study aims to outline the key factors associated with Johne's' disease while outlining its significant impact on the dairy sector.

Mycobacterium Avium Paratuberculosis: A Disease Burden on the Dairy Industry

Mycobacterium avium paratuberculosis is responsible for paratuberculosis or Johne's disease in cows, having economic impacts on the dairy industry and a prevalence rate exceeding 50% in dairy herds. The economic burden of Johne's disease relates to decreased milk production and costs of disease prevention, treatment, and management, while having an economic impact on dairy producers, processors, consumers, and stakeholders of the dairy industry. Determining the true economic impact of the disease is difficult at regional and farm level as symptoms are not evident in subclinically infected animals. At present, the virulence, pathogenicity, persistence, and infectious dose of M. avium paratuberculosis are poorly understood, consequently effective paratuberculosis control measures remain obscure. M. avium paratuberculosis is potentially zoonotic with foodborne transmission a public health risk due to a possible causative link with inflammatory bowel disease in humans. A preventive approach is necessary to reduce the presence of this drug-resistant pathogen in dairy herds and subsequently dairy food. The use of inefficient diagnostic tests coupled with the long latency period of infection results in delayed animal culling and trade of asymptomatic animals, leading to regional transmission and increased disease prevalence. To date, there has been limited success at controlling and treating this terminal endemic disease, leading to significant prevalence rates. This study aims to outline the key factors associated with Johne's' disease while outlining its significant impact on the dairy sector.

Mycobacterium avium: an Emerging Pathogen for Dog Breeds with Hereditary Immunodeficiencies

Purpose of Review

Among the nontuberculous mycobacteria (NTM), Mycobacterium avium complex (MAC) is the leading cause of pulmonary disease in humans. Innate and acquired immunodeficiencies have been associated with an increased host susceptibility to NTM infections. The underlying mechanisms predisposing humans and dogs to MAC infections is being elucidated.

Recent Findings

Although MAC infection is infrequently diagnosed in dogs, a strong breed predisposition particularly for Miniature Schnauzer and Basset Hound dogs is evident. A recessively inherited defect of the adaptor protein CARD9 has recently been documented to be responsible for the increased susceptibility to MAC in the Miniature Schnauzer breed.

Summary

Given the zoonotic potential of a MAC infected dog particularly to immunocompromised human patients, diseased dogs pose a public health risk. While not a reportable disease, treatment of systemic mycobacteriosis is generally not effective and discouraged in dogs. The collaborative efforts by microbiologists, veterinary clinicians, dog breeders, primary care physicians, and infectious disease specialists applying the One Health approach is therefore crucial for the best management and prevention of MAC infection.

Paratuberculosis in dairy goat flocks from southern Spain: risk factors associated with seroprevalence

BACKGROUND

Paratuberculosis (PTB) is a chronic, enteric wasting disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP), with a worldwide distribution. Andalusia, located in southern Spain, is one of the European regions with the highest goat census and the highest milk production; however, current data on the prevalence of MAP in this species are not available.

METHODS

A cross-sectional study was performed to determine the seroprevalence and risk factors associated with PTB in dairy goat flocks from southern Spain. A total of 3312 serum samples were collected from 48 flocks located in three different geographical areas. Health and productive parameters were surveyed during the visit to the herds.

RESULTS

A total of 511 goats were seropositive, with overall true seroprevalence of 22.54 per cent (95 per cent confidence interval (CI₉₅) 21.12-23.97). Of the goat herds, 87.50 per cent (CI₉₅78.14-96.98) were seropositive. The intraherd seroprevalence was 25.43±31.71, distributed as follows: 22 flocks with a seroprevalence under 10 per cent; 18 flocks between 10 per cent and 50 per cent; and eight flocks with a frequency over 50 per cent. Multivariate logistic regression showed significant association between PTB seropositivity and the following variables: intensive production system, lack of management by batches, inappropriate ventilation and seropositivity to c aprine a rthritis e ncephalitis v irus ( CAEV ).

CONCLUSIONS

The results indicate a widespread PTB infection in goat herds in southern Spain. Thus, control programmes must include management and sanitary measures to reduce the prevalence. Further experimental studies are necessary to determine the influence of CAEV-PTB coinfection on immune status.

An update on Mycobacterium avium subspecies paratuberculosis antigens and their role in the diagnosis of Johne's disease

Mycobacterium avium subsp. paratuberculosis (MAP) is responsible for Johne's disease (JD) or paratuberculosis. Diagnosis of MAP infection by measuring host cell-mediated and humoral immune responses has been a major focus in MAP research. For this purpose, several MAP antigens such as secreted protein, cell envelope protein, cell-mediated immune and lipoprotein antigens have been identified and tested to measure their diagnostic utility with varying degree of success. Identifying the optimal antigen or antigen combinations for diagnosis of infected animals is hindered by the complex nature of the disease, prolonged subclinical infection, the differential expression of antigens and scarcity of well characterized MAP-specific epitopes making selection of a single MAP antigen very difficult. Thus, multiplexing of antigens with larger scale and longitudinal studies may lead to development of cost-effective next generation serodiagnostics. This mini review focuses on the role of different MAP antigens in the diagnosis of JD.

Application of Transcriptomics to Enhance Early Diagnostics of Mycobacterial Infections, with an Emphasis on Mycobacterium avium ssp. paratuberculosis

Mycobacteria cause a wide variety of disease in human and animals. Species that infect ruminants include M. bovis and M. avium ssp. paratuberculosis (MAP). MAP is the causative agent of Johne’s disease in ruminants, which is a chronic granulomatous enteric infection that leads to severe economic losses worldwide. Characteristic of MAP infection is the long, latent phase in which intermittent shedding can take place, while diagnostic tests are unable to reliably detect an infection in this stage. This leads to unnoticed dissemination within herds and the presence of many undetected, silent carriers, which makes the eradication of Johne’s disease difficult. To improve the control of MAP infection, research is aimed at improving early diagnosis. Transcriptomic approaches can be applied to characterize host-pathogen interactions during infection, and to develop novel biomarkers using transcriptional profiles. Studies have focused on the identification of specific RNAs that are expressed in different infection stages, which will assist in the development and clinical implementation of early diagnostic tests.

Mycobacterium avium subspecies paratuberculosis: A possible causative agent in human morbidity and risk to public health safety

Mycobacterium avium subspecies paratuberculosis is a bacterial parasite and the causative agent of paratuberculosis, a disease predominately found in cattle and sheep. Infection with this microorganism results in substantial farming economic losses and animal morbidity. The link between infection with this pathogen and human disease has been theorised for many years with Crohn's disease being one of many suspected resultant conditions. Mycobacterium avium may be spread from animal to human hosts by water and foodborne transmission routes, where the foodborne route of exposure represents a significant risk for susceptible populations, namely children and the immune-compromised. Following colonisation of the host, the parasitic organism evades the host immune system by use of molecular mimicry, displaying peptide sequences similar to that of the host cells causing a disruption of self-verses non self-recognition. Theoretically, this failure to recognise the invading organism as distinct from host cells may result in numerous autoimmune conditions. Here, the author presents current information assessing the link between numerous diseases states in humans such inflammatory bowel disease, Type 1 diabetes, rheumatoid arthritis, Hashimoto\'s thyroiditis, multiple sclerosis and autism following infection with Mycobacterium avium paratuberculosis. The possibility of zoonotic transmission of the organism and its significant risk to public health safety as a consequence is also discussed.