Comparative evaluation of diagnostic tests for the detection of Mycobacterium avium subsp. paratuberculosis in the tissues of sheep affected with distinct pathology of paratuberculosis

Aims and objective: Paratuberculosis or Johne's disease is a chronic infectious granulomatous enteritis, mainly of cattle, sheep, goats, and other domestic and wild animals caused by Mycobacterium avium subsp. paratuberculosis (MAP). Currently, MAP has been recognized as an important animal pathogen with significant zoonotic and public health concerns. The early detection of infected animals using suitable diagnostic methods helps in developing control and preventive strategies for the herd. Therefore, the present study was aimed to determine the comparative efficacy of certain diagnostic methods used in the identification and confirmation of MAP in the ovine tissues with distinct pathology of paratuberculosis. Methods: The ileum and mesenteric lymph node (MLN) tissues were collected from 38 sheep infected with paratuberculosis from organized farms of Rajasthan. These animals were further classified as paucibacillary (PB; n = 15) or multibacillary (MB; n = 23) on the basis of histopathological findings and mycobacterial loads. The ileum and MLN tissues of these animals were subjected to IS900 and 251 gene polymerase chain reaction (PCR) and bacterial culture. The tissue sections from MB, PB, and uninfected control sheep groups were stained using indirect immunoperoxidase technique (IPT) and Ziehl–Neelsen (ZN) method. Results: On bacterial culture examination of the ileum and MLN tissues using Herrold's egg yolk medium, MAP was isolated in 14 (60.9%) MB and 5 (33.3%) PB sheep. Of 38 sheep, IS900 PCR detected 21 (55.2%) positive for MAP, of which 19 (82.6%) were MB and 2 (13.3%) were PB sheep. Similarly, 251 gene PCR detected 25 (65.7%) sheep positive for MAP infection, of which 21 (91.3%) were MB and 4 (27%) were PB sheep. Thus, 251 gene PCR was found superior to IS900 PCR in the detection of MAP from the tissues. In PB sheep, IPT and ZN tests were positive in 87.5% and 50% of ileum sections and 70% and 37.5% in MLN sections, respectively. In MB sheep, IPT and ZN tests detected all animals as positive for MAP organisms or antigen and had equal sensitivity in the detection of MAP. The overall sensitivity of IPT was found superior (95%) to ZN staining (80%) in the demonstration of acid-fast bacteria or its antigen in the tissues. Conclusion: The sensitivity of all the tests in the detection of MAP was lower in PB sheep than in MB sheep. Bacterial culture detected MAP in only 50% of sheep and was found less sensitive than other tests used in the present study. Comparing the overall sensitivity of both the PCR assays, 251 gene PCR was found superior to IS900 gene PCR. The sensitivity of IPT was found superior (95%) to the ZN staining (80%) in the demonstration of acid-fast bacteria in the tissues. In the present study, IPT was found superior in the detection of MAP in PB and MB form of ovine paratuberculosis. This test can be used in the confirmation of post mortem diagnosis and research of paratuberculosis along with histopathology. However, 251 gene PCR assay was found easier to perform than IPT and could be used as paratuberculosis screening test in endemic sheep farms for blood and fecal samples

Expression of inflammatory cytokine and inducible nitric oxide synthase genes in the small intestine and mesenteric lymph node tissues of pauci- and multibacillary sheep naturally infected with Mycobacterium avium ssp. paratuberculosis

Objective/Background: Paratuberculosis (Johne's disease) is a chronic infectious granulomatous enteritis, primarily affecting ruminants, and caused by Mycobacterium avium ssp. paratuberculosis (MAP). The disease is widely prevalent throughout the world with significant economic losses. MAP has also been implicated with human Crohn's disease. There exists a strong correlation between the immune response and development of various types of pathologies in ruminants. The polarization of the immune response, which is critical to clinical outcome of the paratuberculosis infection, is controlled by the differential expression of certain cytokines and inducible nitric oxide synthase (iNOS) in Johne's disease. In previous studies, the role of different cytokines (Th1 and Th2) has been occasionally studied in sheep paratuberculosis. In the present study, we studied differential expression of interferon (IFN)-γ, interleukin (IL)-1α, IL-10, transforming growth factor (TGF)-β, iNOS, and TRAF1 genes in MAP-infected sheep and established relationship with distinct pathologies. Methods: Tissue sections (small intestine, ileocecal junction, and mesenteric lymph nodes) were collected from sheep suspected for Johne's disease and appropriately preserved for RNA extraction, polymerase chain reaction (PCR) analysis, and histopathology. Pathologic grading was done on the basis of nature and extent of cellular infiltration, granuloma formation and abundance of acid-fast bacilli. Six sheep each with pauci (PB)- and multibacillary (MB) lesions and six healthy control sheep were selected for cytokine studies. MAP in tissue extracted genomic DNA of sheep was quantified by a quantitative PCR assay. Tissue extracted RNA was reversed transcribed to prepare c-DNA from which quantitative reverse transcription PCR (qRT-PCR) was performed to amplify IFN-γ, IL-1β, IL-10, TGF-β, β-actin, TRAF1, and iNOS with Quantitect SYBR Green Master Mix. qRT-PCR data were analyzed using 2−ΔΔCT method using β-actin gene as a control. All qRT-PCR results were compared by using one-way analysis of variance (least significance difference and Duncan tests) for p-value using SPSS (version 7.5) for expression of each gene in tissues from infected and control sheep. Results: In the small intestine, PB sheep showed significant enhancements in the expression of IL-10, TGF-β, iNOS, and IFN-γ in comparison to similar tissues from uninfected control sheep. IL-1α expression was significantly reduced (p <0.01). The expression of IL-10 in the mesenteric lymph node (MLN) tissue of PB sheep was significantly increased (p <0.01) as compared with the control sheep. MB sheep revealed significantly enhanced expression of TGF-β mRNA and reduction in the expression of IL-1α in comparison to control sheep. In the MLN of MB sheep, the expressions of IL-10 and TGF-β were significantly (p <0.01) increased, and IFN-γ was significantly downregulated in comparison to uninfected control sheep. When the cytokine expression was compared between two distinctly infected groups, the MB sheep showed highly significant decrease (p <0.01) in the expression of iNOS and IFN-γ in the small intestine and IFN-γ in the MLN tissues. Conclusion: The present study indicated that IFN-γ and iNOS were found to play important role in the induction of Th1 type immune response in PB sheep. MB sheep had significant reduction in expression of IFN-γ and iNOS and elevation of IL-10 and TGF-β, which was typical of Th2 cytokine pattern. Elevated expression of IL-10 and TGF-β in PB cases possibly suggests the role of T-regulatory cells and may follow an independent mechanism not typical of Th1 pattern. In view of significantly reduced expression in both forms of the disease, IL-1α may not be an important cytokine in ovine paratuberculosis

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Not AvailableA quantitative real-time PCR (qPCR) assay employing IS900 gene specific primers of Mycobacterium avium subsp. parartuberculosis (MAP) was compared with conventional PCR, bacterial culture and enzyme-linked immunosorbent assay in 38 sheep showing granulomatous enteritis and lymphadenitis with and without demonstration of acid-fast bacilli (AFB). The lesions were classified as multibacillary (MB) (n = 23), which had diffuse granulomatous lesions with abundant AFB, and paucibacillary (PB) (n = 15), which had focal or multifocal granulomatous lesions with few or no AFB. In the multibacillary group (MB), IS900 PCR detected 19 (82.6%), and qPCR detected all 23 (100%) sheep positive for MAP in the intestine and lymph node tissues. In the paucibacillary group (PB), IS900 PCR detected 2(13.3%), and qPCR detected all 15 (100%) sheep positive for MAP in tissues. When results of both groups were taken together, IS900 PCR detected 21(55.2%), and qPCR detected all 38 (100%) animals positive for MAP genome either in the intestine or lymph node tissues. On Herrold egg yolk medium, tissues of 14 (60.9%) MB and 5 (33.3%) PB sheep were found to be positive for MAP. Out of 27 sheep (PB = 8, MB = 19) tested by an ELISA, 21 (77.7%) were found to be positive for MAP antibody, of which 25% (2/8) and 100% (19/19) sheep were from PB and MB sheep,respectively. Based on the results of the present study, it was concluded that qPCR was a highly sensitive test in comparison to conventional PCR, ELISA and bacterial culture for the diagnosis of paratuberculosis on infected tissues especially from paucibacillary sheep.Not Availabl

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Not AvailableLymphadenitis cases in a dromedary camel herd located at Bikaner, Rajasthan, India is reported. Enlargement and suppuration of one or more peripheral lymph nodes including parotid, maxillary, prescapular, inferior cervical and popleteal lymph nodes were observed. The overall morbidity rate was 11.37%. Morbidity rate was highest in female and male animals in the age group of 6 years and above. The male and female animals below 2 years of age were least affected. The genomic DNA extracted from pure bacterial culture was sequenced and the NCBI blast analysis of the 16s rDNA sequences revealed 98 per cent homology with C. pseudotuberculosis. In vitro antimicrobial sensitivity testing revealed that the isolate was sensitive to many antibacterial agents but resistant to cloxacillin. The surgical drainage of pus and parenteral therapy with enrofloxacin resulted into clinical recovery.Not Availabl

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Not AvailableParatuberculosis is an economically important, chronic, and incurable disease in ruminants, caused by Mycobacterium avium subspecies paratuberculosis (MAP). Understanding the genetic variability of MAP strains is important in diagnosis, epidemiological investigation, and the formation of strategies for prevention and control of the disease. Methods: In the present study, a total of 61 MAP isolates obtained from different parts and species of India were typed using IS1311 polymerase chain reaction-restriction endonuclease analysis (PCR-REA) to analyze the genetic difference(s), if any, between them and the host adaptation. Results: Based on PCR-REA results, bison B type was detected in 54 (87%) MAP isolates obtained from cattle, sheep, and goats. Of these, 19 were from sheep of the Rajasthan (n = 17) and Bareilly (n = 2), North India regions, 28 were from cattle of Chennai, South India (n = 3), Bareilly, North India (n = 3), and Nagpur, West India (n = 22), and seven goat isolates from Bareilly, North India region. The ‘C’ type strain was detected in only seven cattle isolates obtained from the Bareilly region. Conclusion: The study revealed that in India, bison B-typeMAP strainswere prevalent in most of the ruminant species. These results have important epidemiological implications with regard to control and prevention of paratuberculosis in India.Not Availabl

Molecular epidemiology of Mycobacterium avium subspecies paratuberculosis in ruminants in different parts of India

Objective/Background: Paratuberculosis is an economically important, chronic, and incurable disease in ruminants, caused by Mycobacterium avium subspecies paratuberculosis (MAP). Understanding the genetic variability of MAP strains is important in diagnosis, epidemiological investigation, and the formation of strategies for prevention and control of the disease. Methods: In the present study, a total of 61 MAP isolates obtained from different parts and species of India were typed using IS1311 polymerase chain reaction-restriction endonuclease analysis (PCR-REA) to analyze the genetic difference(s), if any, between them and the host adaptation. Results: Based on PCR-REA results, bison B type was detected in 54 (87%) MAP isolates obtained from cattle, sheep, and goats. Of these, 19 were from sheep of the Rajasthan (n = 17) and Bareilly (n = 2), North India regions, 28 were from cattle of Chennai, South India (n = 3), Bareilly, North India (n = 3), and Nagpur, West India (n = 22), and seven goat isolates from Bareilly, North India region. The ‘C' type strain was detected in only seven cattle isolates obtained from the Bareilly region. Conclusion: The study revealed that in India, bison B-type MAP strains were prevalent in most of the ruminant species. These results have important epidemiological implications with regard to control and prevention of paratuberculosis in India

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Not AvailableAim: This study was aimed to detect ovine pulmonary adenocarcinoma (OPA) in sheep flocks affected with pulmonary disorders at organized farm. Materials and Methods: A total of 75 sheep died naturally were thoroughly examined for the lesions of OPA during necropsy. Tissue sections from affected portion of the lungs from each animal were collected aseptically and divided into two parts; one each for polymerase chain reaction (PCR) and another for histopathology. Results: On PCR examination of lung tissues, six sheep (8%) were found to be positive for JSRV. Two of them were 3-6 months of age and did not show clinical signs/gross lesions of OPA. Four adult sheep positive on PCR revealed characteristic lesions of OPA on gross and histopathological examination. Conclusion: In the absence of known specific antibody response to the infection with JSRV, there is no diagnostic serological test available. The PCR assay employed in this study on lung tissues, using primers based on the U3 region of the viral long terminal repeat for JSRV would be helpful in the screening of preclinical and clinical cases of OPA in sheep.Not Availabl

Diagnosis and prevalence of ovine pulmonary adenocarcinoma in lung tissues of naturally infected farm sheep

Aim: This study was aimed to detect ovine pulmonary adenocarcinoma (OPA) in sheep flocks affected with pulmonary disorders at organized farm. Materials and Methods: A total of 75 sheep died naturally were thoroughly examined for the lesions of OPA during necropsy. Tissue sections from affected portion of the lungs from each animal were collected aseptically and divided into two parts; one each for polymerase chain reaction (PCR) and another for histopathology. Results: On PCR examination of lung tissues, six sheep (8%) were found to be positive for JSRV. Two of them were 3-6 months of age and did not show clinical signs/gross lesions of OPA. Four adult sheep positive on PCR revealed characteristic lesions of OPA on gross and histopathological examination. Conclusion: In the absence of known specific antibody response to the infection with JSRV, there is no diagnostic serological test available. The PCR assay employed in this study on lung tissues, using primers based on the U3 region of the viral long terminal repeat for JSRV would be helpful in the screening of preclinical and clinical cases of OPA in sheep

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Not AvailableLymphadenitis cases in a dromedary camel herd located at Bikaner, Rajasthan, India is reported. Enlargement and suppuration of one or more peripheral lymph nodes including parotid, maxillary, prescapular, inferior cervical and popleteal lymph nodes were observed. The overall morbidity rate was 11.37 per cent. Morbidity rate was highest in female and male animals in the age group of 6 years and above. The male and female animals below 2 years of age were least affected. The genomic DNA extracted from pure bacterial culture was sequenced and the NCBI blast analysis of the 16s rDNA sequences revealed 98 per cent homology with C. pseudotuberculosis. In vitro antimicrobial sensitivity testing revealed that the isolate was sensitive to many antibacterial agents but resistant to cloxacillin. The surgical drainage of pus and parenteral therapy with enrofloxacin resulted into clinical recovery.Not Availabl