Diagnostic Application of IS900 PCR Using Blood as a Source Sample for the Detection of Mycobacterium avium Subspecies Paratuberculosis in Early and Subclinical Cases of Caprine Paratuberculosis

Active surveillance and associated epidemiological risk factors of caprine paratuberculosis in selected district of Odisha, India

Caprine paratuberculosis (PTB) is a progressive, debilitating and production-limiting disease that causes significant economic losses and raises public health concerns. The goal was to study active surveillance and associated epidemiological risk factors of caprine PTB in selected district of Odisha, India. The 818 goats of various ages, sexes and breeds were randomly screened in ten different districts for a year based on history, clinical signs and fecal smear examination using the Ziehl-Neelsen stain, yielding an overall prevalence of 38.75%, with clinical and sub-clinical PTB at 8.06 and 30.68%, respectively. A molecular tool, IS900 polymerase chain reaction, was also used to confirm the disease. With Mycobacterium avium subsp. paratuberculosis (MAP) bacilli and endoparasite infections, the majority of affected goats (69.08%) were low shedders. Puri coastal district had the highest prevalence (52.29%) followed by Sambalpur (48.61%), while Khordha had the lowest prevalence (26.41%). Caprine PTB was more common in goats over 2 years old (51.23%), in the Ganjam breed (42.30%), in females (39.17%) and in goats housed on earthen floors (55.83%) according to chi-square analysis. The current study concluded that higher (30.68%) observations of subclinical PTB were cause of real concern due to its insidious spread as well as its zoonotic significance with potential human consequences, which requires immediate attention at all levels. Because of the public health importance of this hidden killer disease, the current findings would be useful in developing a roadmap for implementing prevention and control policies, prompting provision for adequate funding with elaborative research.

Evaluation of Immune Exhaustion and Co-Inhibitory Receptor Expression in Mycobacterium avium Subspecies paratuberculosis (MAP) Seropositive Diarrhoeic Bovines

Mycobacterium avium subspecies paratuberculosis (MAP) infection leads to chronic, persistent granulomatous enteritis, causing prolonged diarrhoea and emaciation. The disease is managed using medications such as antibiotics, live vaccines, mycobacteriophage therapies and other treatments; however, a notable proportion of affected animals do not show improvement with this approach. We hypothesise that immunoinhibitory receptors TIM-3 (T cell immunoglobulin mucin protein-3) and PD-1 (Programmed death receptor 1) may be upregulated on Peripheral blood mononuclear cells (PBMCs) of MAP-seropositive bovines, potentially contributing to immune exhaustion. Samples (blood and faeces) were collected from 32 diarrhoeic bovines suspected of MAP infection; eight apparently healthy buffaloes from the dairy farm at Hisar, Haryana and from 14 cows (suffering from chronic diarrhoea, weakness and emaciation) housed in stray cattle shed. MAP infection was estimated using indigenous ELISA (i-ELISA), faecal IS900 PCR, culture and acid-fast staining. TIM-3 and PD-1 gene expression on PBMCs were determined using qRT-PCR. TIM3 expression was relatively higher (~400-fold, 330-fold, 112-fold, 65-fold and 16-fold) in 5 chronically diarrhoeic PBMCs samples (MAP-seropositive), and higher PD-1 expression (around ~7-fold, 1.75-fold, 2.5-fold, 7.6-fold) was recorded in 4 diarrhoeic MAP-seropositive animals, compared to apparently healthy and other MAP-seronegative diarrhoeic animals. High co-expression of TIM-3 and PD-1 levels was also recorded in chronically diarrhoeic, emaciated stray cattle. Understanding immune responses in field conditions might aid in the therapeutic management of paratuberculosis.

Multiplex qPCR for differentiation of Mycobacterium avium subspecies paratuberculosis in active and passive infection of goats

Mycobacterium avium paratuberculosis (MAP) is causative agent of Johne's disease (JD) in domestic animals and has broad host range. JD infected animals shed viable MAP in their milk, feces, blood, and tissues which get transmitted to human beings directly or indirectly by consumption of animal products, through contact, animal handling and through contaminated environment, aerosols. In this current study, we developed hydrolysis probe based TaqMan® real-time PCR assay where samples were investigated by targeting IS900 mRNA and ModD gene to differentiate live MAP shedders from inactive/dead MAP bacilli shedding animals. The IS900 mRNA and ModD gene primers were designed using discontiguous unique conserved sequences of IS900 more towards the 3' end and fibronectin attachment protein (FAP) genes, respectively. Two different reporter dyes Cy5 and TexasRed, with compatible quenchers BHQ-1 and BHQ-2, respectively, were used for probe designing of IS900 and ModD genes. Triplex PCR assay was developed by using serially diluted positive MAP culture in log₁₀ dilution and probe and template titration. TaqMan® probe real-time PCR targeting IS900 mRNA and ModD gene detects the MAP infection at early stage with high sensitivity and specificity. The specificity of developed TaqMan probe real-time PCR was found to be high while validated by using Escherichia coli and Staphylococcus aureus in addition to the MAP culture as there is no non-specific signal from other microbes. The sensitivity of developed TaqMan® probe real-time PCR was computed based on copy numbers ranged from 4.14 × 10¹¹ to 4.14 × 10⁴ for IS900 (FAM), 1.27 × 10¹¹ to 1.27 × 10⁴ for IS900 mRNA (Cy5), and 3.68 × 10¹⁰ to 3.68 × 10⁴ for ModD (TexasRed), and lowest limit to detect MAP was 4.14 × 10⁴, 1.27 × 10⁴, and 3.68 × 10⁴ copies for respective genes. This assay would be of great aid to contain the MAP infection in the large herd, where silent shedders spread active infection can be differentiated from passive shedding by non-infected animals. This test would also be equivalent to culture test in terms of specificity and hence can be able to be undertaken in molecular epidemiological studies to represent the actual disease prevalence in the future. KEY POINTS: • Multiplex mRNA-based qPCR was developed to identify the actively infective MAP bacilli from passive ones. • ModD and IS900 used as targets to assess active MAP bacilli in fecal samples of suspected animals. • The LOD was computed using copy numbers with 4.14 × 10⁴ and 3.68 × 10⁴ copies for IS900 and ModD, respectively.

In vivo kinetics of peripheral cellular immune responses in Mycobacterium avium subspecies paratuberculosis (MAP) infected and vaccinated goats

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of paratuberculosis (ParaTB) also known as Johne's disease (JD) in ruminants, which is characterized by chronic intestinal inflammation. A similar counterpart has been observed in the form of Crohn's disease in humans. The present study is the first trail in goats to understand the peripheral cellular immune responses following experimental MAP infection and vaccination. Fifteen apparently healthy male kids (3-6 months old) of Barbari breed were included in this study. In the experimental study, 5 kids were infected with 'S 5' strain of MAP ("Indian Bison Type"), 5 were vaccinated (Indigenous Vaccine) against MAP infection (Singh et al., 2007) and the remaining 5 kids were uninfected and non-vaccinated controls. Kids were observed for a period of 180 days post exposure (infection and vaccination) and were tested for development of infection. Cellular immune responses (in blood) were recorded post-exposure by three assays. We measured the frequencies of CD4 and CD8T cells, estimated plasma IFNγ and TNα and in the third assay, in vitro cytokine production by peripheral blood mononuclear cells (PBMCs) from vaccinated, infected and controls were examined in response to polyclonal stimulation. The frequencies of peripheral CD4 and CD8T cells were comparable in control, infected and vaccinated animals except around day 49 post-infection where MAP infected animals showed a trend towards significantly reduced frequencies of CD4 T cells compared to apparently healthy controls. Significantly reduced plasma TNFα levels were also observed in infected animals compared to vaccinated animals,during the course of infection. Diminished levels (although non significant) of TNFα were observed in the supernatants from polyclonally stimulated PBMCs at around day 49 post infection. It is conceivable that the diminished cellular immune responses may coincide with an impairment (immune exhaustion) of perhaps antigen-specific CD4T cells that might, in the course of infection, contribute to the progressive nature of caprine paratuberculosis.

Using Omics Approaches in the Discovery of Biomarkers for Early Diagnosis of Johne's Disease in Sheep and Goats

Simple Summary

Johne’s disease (JD) is caused by Mycobacterium avium subsp. paratuberculosis (MAP) and is an important and emerging problem in livestock. Most JD research has been carried out on cattle, but interest in the pathogenesis and diagnosis of this disease in sheep and goats is greatest in developing countries. Sheep and goats are also a relevant part of livestock production in Europe and Australia, and these species provide an excellent resource to study and better understand the mechanism of survival of MAP and gain insights into possible approaches to control this disease. This review gives an overview of the literature on paratuberculosis in sheep and goats, highlighting the immunological aspects and the potential for “omics” approaches to identify effective biomarkers for the early detection of infection.

Abstract

Johne’s disease (JD) is caused by Mycobacterium avium subsp. paratuberculosis (MAP) and is an important and emerging problem in livestock; therefore, its control and prevention is a priority to reduce economic losses and health risks. Most JD research has been carried out on cattle, but interest in the pathogenesis and diagnosis of this disease in sheep and goats is greatest in developing countries. Sheep and goats are also a relevant part of livestock production in Europe and Australia, and these species provide an excellent resource to study and better understand the mechanism of survival of MAP and gain insights into possible approaches to control this disease. This review gives an overview of the literature on paratuberculosis in sheep and goats, highlighting the immunological aspects and the potential for “omics” approaches to identify effective biomarkers for the early detection of infection. As JD has a long incubation period before the disease becomes evident, early diagnosis is important to control the spread of the disease.

Prevalence of Mycobacterium avium subspecies paratuberculosis (MAP) infection in suspected diarrhoeic buffaloes and cattle reporting at Veterinary University in India

Murrah buffaloes, best breed for milk production are native of Haryana state. They contributes significantly to the farmer's income, livelihood and food (milk and meat) security, in the semi-tropical regions of North India. Johne's disease though endemic in the domestic livestock of the country, but reports are not available in the buffaloes suffering from morbidity due to progressive weakness and diarrhoea. We estimated the status of JD in diarrhoeic buffaloes and cattle reporting at Veterinary Clinical Complex of Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India, using conventional, serological and PCR assays.141 buffaloes suffering from chronic diarrhoea were screened to estimate sero-prevalence of MAP and 50.0 % young and 53.52 % adult animals were positive. Of 14 cattle screened, none of the young and 66.6 % adult cows were positive. In buffaloes, 66.1 and 6.77 %, fecal samples were positive in microscopy and IS900 PCR, respectively. Sero-prevalence of JD was very high in diarrhoeic buffaloes and cattle from Haryana state of India.Buffaloes positive for Mycobacterium avium subspecies paratuberculosis (MAP) infection had reduced total leukocyte count and lymphocytes.

Genetic Diversity Among Mycobacterium avium Subspecies Revealed by Analysis of Complete Genome Sequences

Mycobacterium avium comprises four subspecies that contain both human and veterinary pathogens. At the inception of this study, twenty-eight M. avium genomes had been annotated as RefSeq genomes, facilitating direct comparisons. These genomes represent strains from around the world and provided a unique opportunity to examine genome dynamics in this species. Each genome was confirmed to be classified correctly based on SNP genotyping, nucleotide identity and presence/absence of repetitive elements or other typing methods. The Mycobacterium avium subspecies paratuberculosis (Map) genome size and organization was remarkably consistent, averaging 4.8 Mb with a variance of only 29.6 kb among the 13 strains. Comparing recombination events along with the larger genome size and variance observed among Mycobacterium avium subspecies avium (Maa) and Mycobacterium avium subspecies hominissuis (Mah) strains (collectively termed non-Map) suggests horizontal gene transfer occurs in non-Map, but not in Map strains. Overall, M. avium subspecies could be divided into two major sub-divisions, with the Map type II (bovine strains) clustering tightly on one end of a phylogenetic spectrum and Mah strains clustering more loosely together on the other end. The most evolutionarily distinct Map strain was an ovine strain, designated Telford, which had >1,000 SNPs and showed large rearrangements compared to the bovine type II strains. The Telford strain clustered with Maa strains as an intermediate between Map type II and Mah. SNP analysis and genome organization analyses repeatedly demonstrated the conserved nature of Map versus the mosaic nature of non-Map M. avium strains. Finally, core and pangenomes were developed for Map and non-Map strains. A total of 80% Map genes belonged to the Map core genome, while only 40% of non-Map genes belonged to the non-Map core genome. These genomes provide a more complete and detailed comparison of these subspecies strains as well as a blueprint for how genetic diversity originated.

Comparison of multiplex and ordinary PCR for diagnosis of paratuberculosis and tuberculosis in blood samples (buffy coat) of cattle and buffaloes

BACKGROUND

Paratuberculosis and tuberculosis (TB) caused by Mycobacterium avium paratuberculosis (MAP) and Mycobacterium tuberculosis complex (MTC), respectively are economically important, chronic debilitating diseases affecting the dairy herds and are also potential zoonotic threats.

AIMS

Differential diagnosis of paratuberculosis and TB in blood samples of cattle and buffaloes.

METHODS

In this study, an in-house developed multiplex polymerase chain reaction (PCR) targeting MAP, Mycobacterium bovis and Mycobacterium smegmatis was used in blood samples (buffy coat) parallel with IS900 PCR and esxB PCR for diagnosis of paratuberculosis and TB, respectively; in a total of 202 cattle and buffaloes.

RESULTS

Out of 202 animals, 12 (5.9%) and 17 (8.4%) animals were positive for MAP by multiplex PCR and IS900 PCR, respectively; from which only 8 (4%) animals were positive by both tests; whereas 4 and 9 animals were exclusively positive by multiplex PCR and IS900 PCR, respectively. None of the animals were found to be positive for M. bovis and M. smegmatis by the multiplex PCR. However, the esxB PCR detected 13 (6.4%) animals positive for TB. In fact, 3 (1.5%) animals were found to be co-infected by both paratuberculosis and TB.

CONCLUSION

The in-house multiplex PCR detected MAP in buffy coat and there was a fair degree of agreement between the multiplex PCR and IS900 PCR in detection of MAP DNA though the latter detected more number of animals to be positive for MAP. Besides, esxB PCR showed a high diagnostic potential and can be used for diagnosis of TB from blood.

Development and evaluation of LAMP-coupled lateral flow device for the detection of MAP in livestock at point of care resource-limited areas

The Mycobacterium avium subspecies paratuberculosis (MAP) causes paratuberculosis (Johne's disease), a systemic and chronic inflammation of intestine that affects bovine, small ruminants like goat and sheep. The disease has a greater economic importance in cattle and in small ruminants. But its effective control is impeded due to lack of rapid and accurate diagnostics. The present study is aimed at developing a LAMP-coupled lateral flow device (LFD) for rapid detection of paratuberculosis in livestock animal species such as cattle and in small ruminants at resource-limited areas. LAMP primers with biotin and FITC end tags were designed for IS900 gene specific for MAP. To determine sensitivity of LAMP assay, 10-fold serial dilutions were made from 10 ng/μl MAP stock DNA and were compared with PCR. The detection limits of LAMP-coupled LFD were defined and reactions were repeated for reproducibility. The specificity was evaluated using other infectious bacteria such as M. bovis, M. tuberculosis, Brucella abortus, Leptospira interrogan, Yersinia enterocolitica, Salmonella typhimurium, Listeria monocytogens, and Staphylococcus aureus. A total of 95 samples turned positive for LAMP-coupled LFD out of 389 fecal samples. All the cultural-positive and PCR-positive samples showed positive in LAMP-coupled LFD. Nine samples with negative cultures turned positive in LAMP assay. The overall sensitivity and specificity of the LAMP-coupled LFD assays were 100% and 97.02% respectively in comparison with the culture as the gold standard method. The sensitivity detection limit of developed assay was 10 fg/μl and specificity was 100%. This assay successfully detected MAP not only by using bacterial DNA but also in clinical fecal samples. The clear band formation at control and test positions was observed on LAMP-coupled LFD. The developed assay is a simple, rapid, easy to perform, and is very useful in early diagnosis of Mycobacterium avium subsp. paratuberculosis at point of care resource-limited areas.

Evaluation of newly developed 'six recombinant secretary proteins based 'cocktail ELISA' and 'whole cell lysate' based 'indigenous ELISA' and tissue microscopy' with 'Gold standard' histo-pathology for the diagnosis of Johne's disease in slaughtered goats and buffaloes

Three screening tests {(newly developed, six recombinant secretory proteins based 'cocktail ELISA', in-house robust 'indigenous ELISA' based on semi-purified protoplasmic antigens and tissue microscopy were evaluated with 'Gold standard', histo-pathology for the diagnosis of Johne's disease in goats and buffaloes. Serum and tissues {mesenteric lymph nodes and intestines) were driven from farmer's goats (n = 77) and buffaloes (n = 40) slaughtered for harvesting meat and farm goats (n = 77), died and necropsied. Twenty seven (35%) goats and 23 (57.5%) buffaloes were positive in all the four tests. Of 134 tissues screened by histo-pathology, 79.8% MLN and 76.8%, intestines, were positive for MAP infection. In tissue microscopy, 55.2 and 52.3%, goats and buffaloes were positive, respectively. Of 117 sera screened by i_ELISA, 58.4 and 70.0%, goats and buffaloes were positive, respectively. Whereas, c_ELISA detected 55.8 and 62.5%, goats and buffaloes, positives, respectively. Twelve tissues (70.5%) of goats necropsied were positive, both in tissue microscopy and histo-pathology. Most significant gross findings were serous atrophy of the fat and mild to moderate, diffuse thickening of terminal ileum, especially at ileo-caecal junction with or without transverse / longitudinal corrugations. In histo-pathology grade III and IV lesions were significantly low as compared to grade I and II. Of the four tests used for screening 268 samples, histo-pathology was most sensitive (78.3%), followed by i_ELISA (62.3%), c_ELISA (58.9%) and tissue microscopy (58.9%). Between two ELISA tests, c_ELISA using six recombinants secretory proteins, had higher specificity as compared to i_ELISA.

Comparative Evaluation of Different Test Combinations for Diagnosis of Mycobacterium avium Subspecies paratuberculosis Infecting Dairy Herds in India

A total of 355 cows were sampled (serum, n = 315; faeces, n = 355; milk, n = 209) from dairy farms located in the Punjab state of India. Faeces and serum/milk samples were screened by acid fast staining and “indigenous ELISA,” respectively. IS900 PCR was used to screen faeces and milk samples. Bio-load of MAP in dairy cows was 36.9, 15.6, 16.3, and 14.4%, using microscopy, serum ELISA, milk ELISA and milk PCR, respectively. Estimated kappa values between different test combinations: serum and milk ELISA, faecal microscopy and faecal PCR, milk ELISA and milk PCR, faecal PCR and serum ELISA were 0.325, 0.241, 0.682, and 0.677, respectively. Estimation of the relative sensitivity and specificity of different tests in the present study indicated that “serum ELISA” and “milk ELISA” were good screening tests, add “milk PCR” was “confirmatory test” for MAP infection. Combination of milk ELISA with milk PCR may be adopted as a model strategy for screening and diagnosis of JD in lactating/dairy cattle herds in Indian conditions.

A polymerase chain reaction and enzyme linked immunosorbent assay based approach for diagnosis and differentiation between vaccinated and infected cattle with Mycobacterium bovis

BACKGROUND

In most African and Arabic countries tuberculosis (TB) causes great economic losses in bovine species and constitutes serious zoonotic problem. As the traditional diagnostic method delay the research because of low sensitivity and specificity, a rapid method of diagnosis is of outmost importance.

AIM

The study was designed to evaluate the two rapid diagnostic methods of TB in cattle, further to differentiate between infected and bacillus Calmette-Guerin (BCG) vaccinated animals.

MATERIALS AND METHODS

Intradermal tuberculin test was applied to 300 cattle. Of these cattle, 15 cattle were vaccinated from cattle negative to tuberculin test with BCG. Blood samples were taken for lymphocyte separation to apply polymerase chain reaction (PCR) upon and for serum preparation for the enzyme-linked immunosorbent assay (ELISA) application, this blood collected from 65 cattle classified into three groups, viz. positive tuberculin test (35 animals), negative tuberculin test (15 animals), and vaccinated cow with BCG (15 animals). From blood samples lymphocytes were separated and the isolated lymphocytes were subjected to PCR and serum for ELISA application. Blood samples, specimens from lymph nodes and specific tissues were taken for PCR and for cultivation and isolation of Mycobacterium bovis.

RESULTS AND CONCLUSIONS

The results of this study revealed that PCR can be used as rapid efficient and accurate diagnostic test in detection of ruminant TB. Moreover, cattle's ELISA reading showed higher sensitivity in positive tuberculin animals. However, the differentiations between vaccinated and infected animals not clear by using a single antigen only.

Expression profiles of different cytokine genes in peripheral blood mononuclear cells of goats infected experimentally with native strain of Mycobacterium avium subsp. paratuberculosis

Paratuberculosis (ParaTB), caused by Mycobacterium avium subspecies paratuberculosis (MAP) is a chronic enteritis of ruminants and may contribute to Crohn's disease in humans. Key features of host immunity to MAP infection include an early pro-inflammatory (Th1-like) response that eventually gives way to a predominant anti-inflammatory (Th2-like) response. Many studies have been conducted to understand the underlying mechanism of misdirected host immune response, however, these studies mainly focused on cattle. The present study is the first attempt to test the hypothesis of shift in Th1 to Th2 like responses during the progression of ParaTB in caprine species (small ruminant). Ten healthy male kids (<6 months old) of the same breed were selected for this study. Of the 10 kids, 6 were experimentally infected with native strain (S5) of MAP ("Indian Bison Type") and the remaining 4 kids were control. Kids were monitored for a period of 12 months post infection (MPI) and were tested for establishment of infection. Expression levels of IFNG, IL2, IL12, IL4, and IL10 genes were estimated before infection and at 4, 8, and 12 MPI in stimulated peripheral blood mononuclear cells (PBMCs) of infected and control kids. The study demonstrated the expression of IFNG and IL2 as classic Th1-like pro-inflammatory signatures; whereas, IL10 exhibited itself as classical Th2-like signature. The study also reports unexpected lowered expression of the IL12 gene simultaneously with increased expression of IFNG, lowered expression of the IL2 gene (compared to IFNG), and suppressed expression of the IL4.

Tissue localisation of Mycobacterium avium subspecies paratuberculosis following artificially induced intracellular and naked bacteraemia

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of Johne's disease or paratuberculosis, a chronic enteritis of ruminants. While Johne's disease is primarily expressed in the gastrointestinal tract, isolation of MAP from extra-intestinal tissues indicates that microbial dissemination via the haematogenous route may occur during the infection. This study examined the movement of peripheral blood mononuclear cells (PBMCs) infected with MAP and the dissemination of MAP following mycobacteraemia induced by IV inoculation over a time frame of 3 days. Viable MAP were detected in the peripheral blood by culture at 24, 48 and 72 h post IV inoculation in 3 of 4 sheep while a fourth sheep was blood culture positive at 24 and 48 h. Seventy-two hours following IV inoculation, MAP in tissues was unevenly distributed. MAP was predominantly distributed to the filtering organs, i.e. the lung, liver and spleen, however MAP was also isolated from lymph nodes, especially those draining the neck. MAP was not isolated from gastrointestinal tissues or lymph nodes, heart or kidney at 72 h following IV inoculation. The rapidity of localisation of MAP to tissues after onset of induced bacteraemia suggests that intermittent seeding into blood in natural infection would be sufficient to account for dissemination.

Efficacy of 'indigenous vaccine' using native 'Indian bison type' genotype of Mycobacterium avium subspecies paratuberculosis for the control of clinical Johne's disease in an organized goat herd

Therapeutic efficacy of a new 'Indigenous vaccine' prepared from native highly pathogenic 'Indian Bison Type' genotype of Mycobacterium avium subspecies paratuberculosis (MAP) of goat origin has been evaluated with respect to control of clinical Johne's disease in naturally infected Mehsana breed of goat in North Gujarat. Fifty goats from Sheep and Goats Research Station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, were randomly divided into 2 groups viz.,'Vaccinated'(n = 35) and 'Control'(n = 15). After vaccination, goats were monitored for physical condition, morbidity, mortality, body weights, shedding of MAP in feces, internal condition, gross lesions and humoral immune responses up to 120 days (at each interval of 30 days). At the end of 120 days trial, there was marked overall improvement in physical condition and body weights of vaccinated goats as compared to 'Control' goats. Vaccinated goats gained significantly (P < 0.05) higher body weights, hardly exhibited any lesions characteristic of JD, had significantly higher (P < 0.01) antibody titers and shedding of MAP was significantly (P < 0.01) reduced. Few of the vaccinated goats were positive for MAP DNA in faecal PCR and blood PCR before vaccination. However, all were found as negative at 120 days post vaccination (DPV). Overall vaccine exhibited effective in restriction of MAP infection and significant improvement in production parameters and reduction in mortality and morbidity due to JD. The trial in the herd will be continued.

Diagnosis of paratuberculosis in goats by cell mediated immune response, conventional and molecular diagnostic techniques

In the present study efficacy of single intradermal Johnin test, acid fast staining of faecal smear and IS 900 faecal polymerase chain reaction tests was evaluated in 200 goats for detection of Mycobacterium avium subsp paratuberculosis. Two hundred goats comprising 150 goats from an organised farm in Trichur district and 50 goats reared under field condition at farmers premise from Malappuram district of Kerala state formed the study population. Faecal smear from all the 200 goats was stained by Ziehl-Neelsen acid fast stain and faecal polymerase chain reaction (PCR) specific for M. avium subsp paratuberculosis (MAP); IS 900 was performed on all samples. All the animals were subjected to single intradermal Johnin test. Out of 200 goats screened for paratuberculosis, six goats (3%), 11 goats (5.5%) and 42 goats (21%) were found positive by Ziehl-Neelsen acid fast staining of faecal smear, single intradermal Johnin test and IS 900 PCR respectively. Results of the present study indicate that amplification of IS 900 insertion element was the most specific and sensitive diagnostic detection method. Single intradermal Johnin test and Ziehl-Neelsen acid fast staining did not show any significant difference.

Culture of Mycobacterium avium subspecies paratuberculosis (MAP) from blood and extra-intestinal tissues in experimentally infected sheep

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of Johne's disease or paratuberculosis, a chronic enteritis of ruminants, and has been suggested to play a role in Crohn's disease in humans. While Johne's disease is primarily expressed in the gastrointestinal tract, isolation of MAP from extra-intestinal tissues indicates that microbial dissemination via the haematogenous route may occur during the infection. Consequently, the occurrence of mycobacteraemia and dissemination to the liver and hepatic lymph node was investigated in 111 sheep. Disseminated infection was detected in 18 of the 53 sheep that were confirmed to be infected following oral exposure to MAP while the bacterium was isolated from the blood of only 4 of these animals. Disseminated infection was detected more frequently from animals with a positive compared to a negative faecal culture result, multibacillary compared to paucibacillary lesions, and clinical compared to subclinical disease. Detection of MAP in blood by culture was significantly associated with increased time post-exposure and clinical disease, with trends for increased detection in animals with multibacillary lesions and positive faecal culture results. Isolation of MAP from blood was difficult in the early stages of the disease and in paucibacillary animals as the bacteraemia may be intermittent, below the limit of detection or MAP may be present in a dormant non-culturable form. Prolonged incubation periods prior to growth in BACTEC were consistent with inhibition of growth or dormancy in some blood cultures.