Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Paratuberculosis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1998

Identification of a gene unique to Mycobacterium avium subspecies paratuberculosis and application to diagnosis of paratuberculosis.

Mycobacterium avium subspecies paratuberculosis (M. paratuberculosis) is the etiologic agent of paratuberculosis (Johne's disease), a chronic granulomatous enteritis in ruminants. Currently, there is a need for improved diagnostic tests because of the lack of methods for accurate, rapid and reliable detection of M. paratuberculosis infection. A M. paratuberculosis gene (hspX) was cloned, sequenced, and a 30 bp species-specific oligonucleotide was synthesized. As an internal control to identify mycobacterial strains, a 33 bp Mycobacterium genus-specific oligonucleotide was synthesized based on the conserved 5' terminus of the mycobacterial recA gene. Dioligonucleotide hybridization (dOH) analysis identified 28/28 (100%) mycobacterial strains and specifically identified 14/14 (100%) reference (ATCC 19698), bovine, ovine and human isolates of M. paratuberculosis. The M. paratuberculosis-specific oligonucleotide distinguished M. paratuberculosis isolates from related mycobacteria, including all closely related members of the Mycobacterium avium complex (MAC) tested in this study. The members of MAC tested in this study included Mycobacterium avium subspecies avium (M. paratuberculosis, Mycobacterium avium subspecies silvaticum (M. silvaticum) and Mycobacterium intracellulare strains. Hybridization was not observed with DNA extracted from a selected group of other bacterial pathogens. The experiments indicate that the dOH analysis is a useful diagnostic tool to detect mycobacterial infection, specifically M. paratuberculosis. The dOH method could be a good alternative to existing assays and will be adapted for specific identification of M. paratuberculosis from faecal samples, mixed bacteriologic cultures, tissue specimens and whole blood.

Amino Acid Sequence↗
PubMed1991

Mycobacterium paratuberculosis monoassociated nude mice as a paratuberculosis model.

In this study, a paratuberculosis (Johne's disease) model was developed by intragastrically dosing gnotobiotic athymic nude mice with Mycobacterium paratuberculosis. The mice infrequently shed bacilli from their intestinal tracts during the first 4 months after inoculation. Following this time, increasing numbers of M. paratuberculosis (greater than 4.0 log10 bacilli per fecal pellet by 40 weeks) were recovered from the feces of the 12 mice that remained in the isolator. A similar pattern of recovery of M. paratuberculosis was obtained from the ileum, cecum, colon, and liver. Histopathologic lesions and acid-fast bacilli were rare during the first 4 months of infection and then, with time, increased in prevalence and severity. Mice maintained for 7 months or longer exhibited severe granulomatous inflammation and large numbers of acid-fast bacilli in the gastrointestinal tract and liver (up to 10(8) log10 colony forming units per gram wet weight). Five mice maintained for 7 months or more developed clinical signs consistent with those seen in paratuberculosis (weight loss, chronic diarrhea); three of these mice eventually died or became moribund and were euthanatized. M. paratuberculosis monoassociated mice released increased levels of tumor necrosis factor activity into their sera, as compared to uninfected control mice, when they were injected with bacterial lipopolysaccharide. The clinical signs, fecal shedding of M. paratuberculosis, granuloma formation, and progressive bacillary multiplication observed with these mice are consistent with naturally occurring M. paratuberculosis infection of ruminants (Johne's disease). This model will be useful for future studies of immunoregulation and antimicrobial therapy of paratuberculosis.

Animals↗
PubMed2001

Paratuberculosis in sheep: its possible role in the epidemiology of paratuberculosis in cattle.

A total of 50 sheep originating from 15 Dutch farms with a known paratuberculosis infection in their cattle herd, but with no history of paratuberculosis infection in their sheep flock, were examined for infection with Mycobacterium avium subsp. paratuberculosis (Map). The sheep had been grazing on the same pastures as the cattle or on pastures fertilised with manure from these cows. The sheep were screened for paratuberculosis by serum biochemistry, serology and intradermal skin tests. At necropsy they were examined macroscopically, microscopically and bacteriologically for paratuberculosis. From 10 sheep, originating from eight flocks, Map could be isolated from various tissues but not from the intestinal contents, after an incubation period of 2.5-4 months. Six of these culture-positive sheep had no macroscopic signs of paratuberculosis at necropsy. Seven sheep were Map culture negative but showed macroscopic and microscopic lesions consistent with a paratuberculosis infection. Results of serology and skin tests did not correlate with the results of bacteriological culture. Serum concentrations of calcium, albumin and total protein of the infected, suspected and negative sheep were not different. These results indicate that a substantial number of the sheep examined were infected with Map. Even though this bacterium was not isolated from their faeces, the possibility that these sheep could have been shedding Map with their faeces below detection level or at a later stage of the disease cannot be eliminated. Map infected sheep should, therefore, be considered as a possible factor in the epidemiology of with Map infected cattle herds in The Netherlands. At necropsy bacteriological culture of Map should be performed on a routine basis to improve the diagnosis of paratuberculosis in sheep.

Animals↗
PubMed2003

Isolation of Mycobacterium avium subsp paratuberculosis from environmental samples collected from farms before and after destocking sheep with paratuberculosis.

OBJECTIVE: To determine whether Mycobacterium avium subsp paratuberculosis could be isolated from soil-pasture, faecal, water and sediment samples on farms before and after removal of sheep with paratuberculosis. A feasibility study and subsequent field survey. PROCEDURE: First the analytical sensitivity of radiometric culture of the organism from two types of soil was determined relative to faeces. Then soil-pasture, faecal, water and sediment samples were collected for culture from a range of sites from 6 farms with paratuberculosis affected sheep and goats. Similar samples were collected from 20 farms at least 9 months after removal of infected stock. RESULTS: The analytical sensitivity of culture of M a paratuberculosis from soil samples was 2 orders of magnitude less than that from faeces, and environmental samples required longer incubation periods to yield significant growth in radiometric culture (BACTEC) medium. However, the organism was recovered from approximately 20% of 163 soil-pasture, water and sediment samples from 6 properties with clinically-affected animals with paratuberculosis. The positive samples were from a range of topographic sites, including open exposed and dry areas, however, low lying areas tended to have larger numbers of organisms. When the same sites were sampled again about 5 months later, only 1 was culture positive, and none were culture positive > 12 months later. Of 17 water and dam sediment samples collected from farm 6, which had long-standing high prevalence OJD infection, only one water sample and one sediment from the same dam were culture positive. None of the 5 water samples from the other farms were culture positive. Of 96 water samples, 90 sediment samples and 93 soil samples from farms that had been destocked of infected sheep/goats for 9 to 24 months, one sediment sample from a farm in Victoria (destocked for 12 months) and two sediment samples from a farm in New South Wales (10, 19 months) were culture positive. Recontamination from cattle or water could not be excluded as a cause of the positive cultures from the second farm. CONCLUSION: M a paratuberculosis can be detected by radiometric culture in environmental samples from farms grazed by sheep or goats with paratuberculosis. There is a relatively low likelihood of recovery of the organism from water samples from such farms, and at 5 or more months after removing stock with paratuberculosis the likelihood of positive cultures from environmental samples is very low. Although the analytical sensitivity of culture from environmental samples is less than that from faeces, surveys of environmental sites are nevertheless feasible. However, improved culture methods are needed for critical surveys and to study the movement and fate of the organism in the environment.

Animals↗
PubMed2001

AhpC, AhpD, and a secreted 14-kilodalton antigen from Mycobacterium avium subsp. paratuberculosis distinguish between paratuberculosis and bovine tuberculosis in an enzyme-linked immunosorbent assay.

Sera from cattle naturally infected with Mycobacterium avium subsp. paratuberculosis (n = 56) and naturally (n = 4) and experimentally (n = 8) infected with Mycobacterium bovis were tested for the presence of antibodies against paratuberculosis antigens. An enzyme-linked immunosorbent assay (ELISA) was established based on absorption of M. avium subsp. paratuberculosis antigens on a hyperimmune antiserum against M. avium subsp. avium proteins in order to remove cross-reacting antigens. This absorbed-antigen ELISA recognized 66% of animals with paratuberculosis (37 of 56), while none of the animals with naturally occurring bovine tuberculosis (TB) had detectable antibodies. However, the animals with experimental bovine TB also responded in this ELISA. Similar results were found in a commercial ELISA, showing that neither of these tests was able to distinguish between paratuberculosis and bovine TB. The sera were further tested for antibody activities against purified AhpC and AhpD, which are proteins constitutively expressed by M. avium subsp. paratuberculosis, and against a secreted 14-kDa protein present in culture filtrates from the M. avium complex. Elevated antibody levels to AhpC, AhpD, and the 14-kDa antigen were found in 27% (13 of 48), 15% (7 of 48), and 27% (13 of 48), respectively, of the cattle with paratuberculosis. Together these ELISAs were positive with 35% (17 of 48) of the animals. None of the animals with bovine TB had detectable antibodies against any of the purified proteins despite their high levels of cross-reacting antibodies. These results show that purified specific antigens are needed to differentiate between paratuberculosis and bovine TB in ELISA.

Animals↗
PubMed1993

Isolation of Mycobacterium paratuberculosis from mononuclear cells in tissues, blood, and mammary glands of cows with advanced paratuberculosis.

Seven mature dairy cows from 6 herds were obtained with history, clinical signs of disease, and laboratory findings suggestive of advanced paratuberculosis. A surgically implanted collection chamber was used to obtain peripheral tissue fluid. Blood, mammary gland flush fluid, and collection chamber flush fluid (CCFF) samples were obtained 6 times over a 2-week period from each cow. Mononuclear cell-rich portions of these fluids obtained by gradient centrifugation were submitted for bacteriologic culture of Mycobacterium paratuberculosis and for total and differential cell counts. Bacteriologic culture of feces for M paratuberculosis and complete necropsy performed on each cow at the conclusion of the study confirmed the diagnosis of paratuberculosis. Numbers of tissue macrophages obtained from CCFF samples were lower than expected. Mean (+/- SD) differential count of tissue macrophages collected from CCFF was 65.57 (+/- 23.39). Mean calculated tissue macrophages (total cell count x differential count) collected from CCFF samples was 623.1 (+/- 784.55) cells/microliters. Mycobacterium paratuberculosis was isolated from 1 of 42 (2.4%) collections of mononuclear cell-rich portions of plasma and from 2 of 42 (4.8%) CCFF samples. Mycobacterium paratuberculosis was not isolated from any collections of mammary gland flush fluid. The collection and processing techniques used in this study did not enhance detection of M paratuberculosis infection in cows with advanced paratuberculosis, beyond that of ileocecal lymph node biopsy or fecal culture.

Animals↗
PubMed2001

Experimental paratuberculosis in calves following inoculation with a rabbit isolate of Mycobacterium avium subsp. paratuberculosis.

The role of wildlife species in the epidemiology of paratuberculosis has been the subject of increased research efforts following the discovery of natural paratuberculosis in free-living rabbits from farms in east Scotland. This paper describes the experimental inoculation of young calves with an isolate of Mycobacterium avium subsp. paratuberculosis recovered from a free-living rabbit. After a 6-month incubation period, all eight calves inoculated with the rabbit isolate had developed histopathological and/or microbiological evidence of M. avium subsp. paratuberculosis infection. Similar results were obtained from a group of calves infected with a bovine isolate of M. avium subsp. paratuberculosis. The virulence of the rabbit isolate for calves demonstrated in this study suggests that rabbits are capable of passing paratuberculosis to domestic ruminants and that wildlife reservoirs of M. avium subsp. paratuberculosis should therefore be considered when formulating control plans for the disease.

Animals↗
PubMed1997

Farm factors associated with the presence of Mycobacterium paratuberculosis infection in dairy herds on the New York State Paratuberculosis Control Program.

An extensive questionnaire was developed and used to collect data from 33 herds that were on the New York State Paratuberculosis Control Program, to study farm factors associated with the presence of Mycobacterium paratuberculosis infection in dairy herds. The results of the last whole herd paratuberculosis fecal culture were used to indicate presence of infection in a herd, with herds having one or more animals positive classified as 'infected'. The average prevalence within herds was 5.2%. Fourteen herds were uninfected and 19 herds had prevalences ranging from 0.7%-28.2%. Data on 31 continuous and 67 categorical risk factors were collected by questionnaire. Ten factors were significantly associated with prevalence risk of infection in the univariable logistic regression. These factors were: the type of farm operation (commercial/registered or both); earlier diagnosis of the disease before entering the control program; number of clinical cases in the previous year; whether clinical cases were raised or purchased animals; typical signs in clinical cases; exposure of calves 0-6 weeks of age to feces of adult cows; contact of young stock with adult animal feces from using the same equipment to clean the housing for both groups of animals; spreading feces on fields from which forage is later harvested and fed to animals of any age group; what is done with animals that are suspected of having paratuberculosis or test positive on culture; and frequency of cleaning the cow barn. Stepwise logistic regression was used to determine the significance of each risk factor while controlling simultaneously for the effect of other factors. The significant factors were the type of farm operation, clinical signs, and exposure of calves to feces of adult cows. Commercial herds, presence of clinical signs typical of paratuberculosis in animals, and exposure of calves 0-6 weeks old to feces of adult cows all indicate a higher likelihood that a herd is infected with M. paratuberculosis.

Animal Husbandry↗
PubMed1990

Isolation of Mycobacterium paratuberculosis from the uterine flush fluids of cows with clinical paratuberculosis.

Mycobacterium paratuberculosis was isolated from the uterine flush fluids obtained from 3 to 4 cows with clinical paratuberculosis. Four cows with clinical paratuberculosis were subjected to uterine lavage, using an established embryo recovery technique, and the recovered fluids were cultured for M paratuberculosis. Mycobacterium paratuberculosis has previously been demonstrated to adhere to bovine ova. Embryos within the uterus of a superovulated cow infected with M paratuberculosis could be exposed to the organism.

Animals↗
PubMed2007

Proteomic comparison of Mycobacterium avium subspecies paratuberculosis grown in vitro and isolated from clinical cases of ovine paratuberculosis.

Paratuberculosis (Johne's disease) poses a significant economic problem to beef, dairy and sheep industries worldwide, and is caused by Mycobacterium avium subspecies paratuberculosis. In this study, 2D PAGE was used as a tool to investigate the virulent state of M. avium subsp. paratuberculosis, incorporating the technique of beating the organism with zirconium/silica beads to provide a comprehensive representation of its proteome. A direct comparison of the proteomes of M. avium subsp. paratuberculosis scraped from the terminal ileum of ovine paratuberculosis cases, and the identical strain grown in vitro, is presented. These analyses identified a set of 10 proteins whose expression is upregulated during natural infection: 1-pyrroline-5-carboxylate dehydrogenase (RocA), a putative acyl-CoA dehydrogenase (FadE14), 2-methylcitrate dehydratase (2-mcd), arginosuccinate synthase (ArgG), universal stress protein (usp), 30S ribosomal protein S2 (RpsB), peptidyl-prolyl cis-trans isomerase (PpiA), luciferase-like monooxygenase (lmo), thiosulfate sulfurtransferase (SseA) and ATP-dependent Clp protease (ClpB). Most of the proteins identified do not have obviously related functions; however, ArgG and RocA function in the same pathway, and may have a concerted action for energy production in vivo.

1-Pyrroline-5-Carboxylate Dehydrogenase↗
PubMed2006

Goat paratuberculosis in Chile: first isolation and confirmation of Mycobacterium avium subspecies paratuberculosis infection in a dairy goat.

In October 2004, 41 goats > 2 years old from a Saanen dairy goat herd located in Purranque County, 10th Region, Chile, were sampled and tested for paratuberculosis. While collecting samples it was observed that several goats were thin and emaciated. One goat was sufficiently debilitated to warrant humane euthanasia. This animal was brought to the Veterinary School at the Universidad Austral de Chile for necropsy. The goat selected for necropsy was a 12-year-old doe. The animal showed classical clinical signs of caprine paratuberculosis: emaciation despite willingness to eat, dry and rough hair coat, and no evidence of diarrhea. Gross pathology and histopathology of the necropsied goat were consistent with paucibacillary paratuberculosis. Bacteriology, serology, and PCR confirmed the diagnosis. This is the first published report of goat paratuberculosis in Chile confirming a case of caprine paucibacillary paratuberculosis.

Animals↗
PubMed1990

Cyclophosphamide and prednisolone exacerbate the severity of intestinal paratuberculosis in Mycobacterium paratuberculosis monoassociated mice.

In this study we examined the effects of continuous oral administration of the immunosuppressive agents cyclophosphamide and prednisolone on the susceptibility of gnotobiotic nu/+ BALB/c mice to intestinal paratuberculosis. Treatment with either cyclophosphamide or prednisolone led to fecal shedding of Mycobacterium paratuberculosis, and increased the numbers of M. paratuberculosis recovered from the intestinal tract and liver, to levels similar to those recovered from untreated nu/nu mice. Numerous acid-fast bacilli and granulomas were observed within the intestinal tracts and livers of cyclophosphamide and prednisolone treated nu/+ and untreated nu/nu mice. In contrast, untreated control nu/+ mice infrequently shed small numbers of bacilli, harbored low numbers of M. paratuberculosis in their intestinal tracts, and did not have visible granulomas and acid fast bacilli in their tissues. Spleen cells from cyclophosphamide and prednisolone treated nu/+ mice, and from untreated nu/nu mice, had a reduced ability to proliferate in vitro in response to mitogen and antigens. These observations are consistent with previous evidence that cellular immunity restricts the development of intestinal paratuberculosis.

Animals↗
PubMed1989

Effects of altered dietary iron intake in Mycobacterium paratuberculosis-infected dairy cattle: sequential observations on growth, iron and copper metabolism and development of paratuberculosis.

Twenty calves were orally inoculated with Mycobacterium paratuberculosis at six weeks old. At six months old, 10 of these, plus four uninfected controls were maintained on limited dietary copper and supplemented iron intake for a further 27 months. During this time all these animals, together with a further four untreated controls, were bred before being killed and examined for evidence of paratuberculosis. Despite significant reduction in weight gain, attributable to both iron supplementation and infection, no significant difference was found in the numbers of iron-supplemented and unsupplemented animals that developed clinical signs nor in the extent and severity of intestinal lesions between groups. Accumulation of iron in paratuberculosis lesions was not affected by iron supplementation but was positively correlated with the frequency of shedding of M paratuberculosis in faeces (P less than 0.05). Dietary iron supplementation alone resulted in serum hyperferraemia, hepatic siderosis and slight hypocuprosis, whereas, in infected animals, this resulted in marked hypocuprosis and anaemia within groups (P less than 0.05). Infection alone resulted in serum hypoferraemia and intestinal and hepatic siderosis which was positively correlated with the severity of infection within groups (P less than 0.05). Susceptibility to paratuberculosis may result from failure ultimately to limit monokine-mediated iron sequestration in intestinal tissue.

Animals↗
PubMed2001

Molecular epidemiological confirmation and circumstances of occurrence of sheep (S) strains of Mycobacterium avium subsp. paratuberculosis in cases of paratuberculosis in cattle in Australia and sheep and cattle in Iceland.

Distinct strains of Mycobacterium avium subsp. paratuberculosis with a tendency to segregate in either sheep, or cattle and other ruminants, have been described and are known as S and C strains, respectively. These strains can be distinguished by a polymorphism in the IS1311 element and other DNA-based methods. C strains are relatively easy to culture from tissues and faeces of animals with paratuberculosis but S strains are difficult to culture. A retrospective survey of archival formalin-fixed paraffin-embedded tissue samples from culture negative Australian paratuberculous cattle was undertaken to determine whether infection in these cases was due to S strains. Polymerase chain reaction and restriction endonuclease analysis of the amplified product was used to identify the polymorphism in IS1311. Three cases of bovine paratuberculosis due to S strain were confirmed from three different farms. A serological survey led to the identification of a further two cases on one of these farms. S strains were also identified in archival tissues from paratuberculous sheep and cattle from Iceland, confirming epidemiological and microbiological evidence that paratuberculosis in Iceland was due to S strain following importation of infected sheep from Europe. In each bovine case in both Iceland and Australia there had been direct or indirect contact of calves with paratuberculous sheep. We were unable to determine whether S strains had established endemic infection in cattle or whether repeated infection from sheep had occurred. Limited epidemiological evidence suggests that transmission of S strains to cattle in Australia has been uncommon under extensive grazing conditions. In Iceland, different husbandry practices appear to have favoured transmission of S strains to cattle.

Animals↗
PubMed1994

Incidence of paratuberculosis after vaccination against M. paratuberculosis in two infected dairy herds.

Vaccination against paratuberculosis of all newborn animals has been performed since April 1984 in two dairy herds with a high incidence of clinical cases of paratuberculosis, using a vaccine containing heat-inactivated M. paratuberculosis in a water/mineral oil emulsion. Animals slaughtered between April 1984 and January 1991 were included in the study. Histology, bacterioscopy and culture on Smith and modified Löwenstein-Jensen media were performed using jejunum, ileum and draining lymph nodes. The animals present on the farm in April 1984 constituted a retrospective non-vaccinated group, giving an indication of the initial infection rate. After vaccination, the percentage of animals culled for clinical paratuberculosis decreased significantly (7.8 to 1.8%; P < 0.005), as did the percentage of animals with positive histology (11.8% to 5%). The incidence of infected animals, defined by positive results in histology and or bacterioscopy and/or culture, however, increased from 21.8% to 25.9%.

Animals↗
PubMed2000

Vaccination against paratuberculosis of lambs already infected experimentally with Mycobacterium avium subspecies paratuberculosis.

OBJECTIVE: To assess the protective value of a live-attenuated vaccine in sheep already exposed to Mycobacterium avium subsp paratuberculosis and to investigate the progression of a systemic immune response in experimentally infected sheep. STUDY DESIGN: Twenty-eight lambs, aged 1 to 1.5 months, were dosed via stomach tube with approximately 4.4 x 10(8) M a paratuberculosis organisms. Two weeks later, 14 of these 28 animals received subcutaneous injections of 1 mL of a live-attenuated vaccine. Thirteen additional lambs were neither dosed nor vaccinated (negative controls). Antigen-induced production of IFN-gamma in blood, and antibody concentrations in serum were sequentially monitored in vaccinated, unvaccinated and control animals for 1 year. Each sheep was examined for infection by an IS900-based PCR test on samples of ileum and ileocaecal lymph node and histological examination at the time of necropsy. RESULTS: Seven of 14 unvaccinated and two of 14 vaccinated sheep developed clinical paratuberculosis that was later confirmed by histological examination and/or the IS900-based PCR test. The granulomatous inflammation in the jejunal and ileal mucosa was less severe in vaccinated than in unvaccinated sheep. Acid-fast organisms were detected only in the unvaccinated group. The PCR assay on ileal samples gave positive reactions in two vaccinated and eight unvaccinated sheep. Both the antibody response and IFN-gamma response were detected earlier and were more substantial in vaccinated than in unvaccinated sheep. Furthermore, in experimentally infected but unvaccinated sheep, the IFN-gamma concentrations were higher in those animals without acid-fast organisms than in those with them. CONCLUSIONS: Vaccination of lambs with live-attenuated vaccine 2 weeks after oral inoculation with M a paratuberculosis stimulated the host response against the organism and led to a reduced mycobacterial burden. The diminished IFN-gamma responses in experimentally infected sheep with acid-fast organisms suggest a positive relationship between the magnitude of the systemic cell-mediated immune response and an animal's ability to control infection.

Animals↗
PubMed2004

Nested PCR on blood and milk for the detection of Mycobacterium avium subsp paratuberculosis DNA in clinical and subclinical bovine paratuberculosis.

OBJECTIVE: To determine the potential of PCR on blood and milk to detect cattle infected with Mycobacterium avium subsp paratuberculosis. PROCEDURE: A nested PCR method probing for IS900 was developed and compared to ELISA serology in 11 clinically infected and 46 subclinically infected, lactating Holstein cows from a herd with confirmed paratuberculosis (Johne's disease). RESULTS: When compared to serum ELISA the nested blood- and milk PCRs were equal in identifying DNA from clinically infected animals. The PCR procedures also gave positive DNA results with some subclinically infected animals when these only gave suspicious or negative results in the ELISA test. Most clinically and subclinically infected animals were detected with milk PCR. CONCLUSION: Since there may well be a haematological phase in paratuberculosis, nested PCR testing of blood and milk samples shows potential to detect animals subclinically infected with M a paratuberculosis. More subclinically infected animals need to be tested and confirmed infected before estimates of sensitivity and specificity can be made.

Animals↗
PubMed1983

Isolation of specific peptides from Mycobacterium paratuberculosis protoplasm and their use in an enzyme-linked immunosorbent assay for the detection of paratuberculosis (Johne's disease) in cattle.

An antigen was isolated from the protoplasm of Mycobacterium paratuberculosis by a combination of gel filtration, ion exchange, and affinity chromatography. The purified antigen constituted 7.8% of the total protein in the protoplasm. The specificity and sensitivity of the enzyme-linked immunosorbent assay (ELISA) for paratuberculosis, using the purified antigen, were evaluated with sera from 104 cattle which were examined (surveyed) for M paratuberculosis infection by fecal cultural technique. The ELISA was positive in 50 of 60 infected animals. Five of 44 noninfected animals were also test-positive. When a crude protoplasmic extract was used as antigen in the ELISA, sera from 37 infected and from 18 noninfected animals were test-positive. Cross-reactions were encountered in both complement-fixation test and the ELISA between crude or partially purified M paratuberculosis antigens and antisera to Nocardia asteroides, M avium, M phlei, and M fortuitum. The purified antigen gave no complement-fixation reaction with any of these antisera. In the ELISA, cross-reaction was not found when purified antigen was used and the sera were screened at 1:40 dilution.

Animals↗