Case definition terminology for paratuberculosis (Johne's disease).

Paratuberculosis (Johne's disease) is an economically significant condition caused by Mycobacterium avium subsp. paratuberculosis. However, difficulties in diagnosis and classification of individual animals with the condition have hampered research and impeded efforts to halt its progressive spread in the global livestock industry. Descriptive terms applied to individual animals and herds such as exposed, infected, diseased, clinical, sub-clinical, infectious and resistant need to be defined so that they can be incorporated consistently into well-understood and reproducible case definitions. These allow for consistent classification of individuals in a population for the purposes of analysis based on accurate counts. The outputs might include the incidence of cases, frequency distributions of the number of cases by age class or more sophisticated analyses involving statistical comparisons of immune responses in vaccine development studies, or gene frequencies or expression data from cases and controls in genomic investigations. It is necessary to have agreed definitions in order to be able to make valid comparisons and meta-analyses of experiments conducted over time by a given researcher, in different laboratories, by different researchers, and in different countries. In this paper, terms are applied systematically in an hierarchical flow chart to enable classification of individual animals. We propose descriptive terms for different stages in the pathogenesis of paratuberculosis to enable their use in different types of studies and to enable an independent assessment of the extent to which accepted definitions for stages of disease have been applied consistently in any given study. This will assist in the general interpretation of data between studies, and will facilitate future meta-analyses.

Mycobacterium avium subsp. paratuberculosis sheep strains isolated from Cyprus sheep and goats.

Paratuberculosis, caused by Mycobacterium avium subsp. paratuberculosis (Map), is a chronic incurable infection of intestinal tract of animals. Molecular characterization of Map isolates classifies them into two major groups, 'Cattle' or Type II and 'Sheep' or Type I/III with a different phenotype, epidemiology, virulence and pathogenesis. The aim of this study was to examine 192 Map ELISA-positive sheep and goats from Cyprus using faecal culture and genotype Map isolates using IS1311 PCR and restriction endonuclease analysis (IS1311 PCR-REA) with HinfI restriction enzyme. Map was isolated from only four (4.6%) faecal samples out of 88 sheep and 15 (14.4%) faecal samples out of 104 goats. Genotyping of the isolates using IS1311 PCR-REA revealed that sheep and goat populations on the island are infected primarily by 'Sheep' strains. Only three Map isolates from goats originated from one farm were characterized as 'Cattle' strains.

Presence of PPE proteins in Mycobacterium avium subsp. paratuberculosis isolates and their immunogenicity in cattle.

Johne's disease or paratuberculosis in cattle is caused by Mycobacterium avium subsp. paratuberculosis (MAP). Although the stages of infection have been well described, very few virulence factors of MAP have been studied in detail. We aimed to study the localization and immunogenicity of members of the polymorphic PPE protein family which is unique to Mycobacteria and has been linked to virulence in Mycobacterium tuberculosis (Mtb). The presence of PPE proteins in the cell wall was investigated by enzymatic digest of surface exposed proteins of live MAP bacteria and analysis by LC-MS/MS. Polyclonal antisera were generated against a recombinant fragment of one PPE protein and a synthetic peptide of the other to confirm their surface exposure. Sera from naturally infected cows were investigated for the presence of specific antibodies against the recombinant PPE protein. Two PPE proteins, Map3420c and Map1506, were detected by mass spectrometry and confirmed to be surface exposed on live MAP cells by immunohistochemistry. The sera from naturally infected animals contained specific antibodies against recombinantly expressed Map3420c as demonstrated by western blotting. These findings show the in vitro expression of two PPE proteins. Additionally the surface exposure and immunogenicity of PPE proteins of MAP was demonstrated.

Mycobacterium avium subspecies paratuberculosis diagnosis and strain typing--present status and future developments.

Mycobacterium avium subspecies paratuberculosis (MAP) is the etiological agent of paratuberculosis, a chronic gastroenteritis of ruminants and has zoonotic importance. We present here a review of MAP with respect to--(i) present diagnostic techniques and important developments; and (ii) MAP strain-typing tools. A summary of the findings to date is presented, and advantages and disadvantages of each of the methods are compared and discussed.

Pathology of spontaneous and experimental infection of North American wild ruminants with Mycobacterium paratuberculosis.

Spontaneous paratuberculosis was studied in free-ranging and captive bighorn sheep (Ovis canadensis), and Rocky Mountain goats (Oreamnos americanus). Lesions of paratuberculosis in these species resembled the disease in domestic sheep and goats. Mycobacterium paratuberculosis cultured from bighorn sheep was used to orally infect bighorn x mouflon (Ovis musimon) hybrid sheep, elk (Cervus elaphus nelsoni), mule deer (Odocoileus hemionus), and white-tailed deer (Odocoileus virginianus). Clinical paratuberculosis developed only in mule deer and was characterized by poor growth and diarrhea. Gross lesions were mild in all species. Enlargement of mesenteric lymph nodes was mild to moderate; the wall of the distal small intestine was affected minimally. Focal to diffuse infiltrates of epithelioid macrophages and giant cells occurred in the cortex of mesenteric lymph nodes, around mesenteric lymphatics, and in the intestinal mucosa. Extraintestinal lymph nodes, spleen, liver, and lung were involved in some animals; focal necrosis and mineralization was present in all species but was severe and widespread in the cervids.