Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
1.
PLoS Negl Trop Dis ; 18(5): e0012223, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38805568

RESUMO

Bovine tuberculosis (bTB) is a chronic zoonotic disease affecting cattle of all age groups including wild animals. It poses a significant threat to public health and high economic losses to dairy farmers. While the disease has been eradicated from most of the developed countries through extensive surveillance, testing and culling strategy, it is endemic in Africa, Asia, and the Middle East countries. Currently, there is limited research regarding the prevalence of bTB in cattle in Bhutan. This study aimed to determine the seroprevalence of bTB in cattle in six districts of eastern Bhutan. A two-stage probability proportional to size (PPS) sampling strategy was used to determine the number of animals from which serum samples needed to be collected in each district and sub-district. All farms and cattle for sampling were randomly selected from the data in the annual livestock census of 2020. The samples were tested using bTB ELISA test kit. The seroprevalence and their 95% confidence intervals were calculated. Logistic regression models were constructed to assess the influence of various individual animal and environmental risk factors (breed, age, sex, source of animal, body condition scores of animals, respiratory system status) associated with sero-positivity in animals. The study revealed an apparent seroprevalence of 2.57% (25/971 cattle; 95% CI:1.58-3.57), with an estimated true seroprevalence of 0.91% (95% CI: 0.0-2.81). However, none of the variables were found to be significantly associated with bTB seroprevalence in cattle. We recommend, further sampling and employment of confirmatory testing to fully ascertain the extent of bTB in the cattle herds in eastern Bhutan for prevention and control.


Assuntos
Tuberculose Bovina , Animais , Bovinos , Butão/epidemiologia , Estudos Soroepidemiológicos , Tuberculose Bovina/epidemiologia , Tuberculose Bovina/microbiologia , Fatores de Risco , Feminino , Masculino , Mycobacterium bovis/imunologia , Prevalência , Anticorpos Antibacterianos/sangue
2.
Antibiotics (Basel) ; 12(2)2023 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-36830321

RESUMO

Data on the use of antimicrobials in humans and livestock may provide evidence to guide policy changes to mitigate the risk of antimicrobial resistance (AMR). However, there is limited information available about antimicrobial use in livestock in low- and middle-income countries, even though these nations are most vulnerable to the impact of AMR. This study aimed to assess the consumption of veterinary antimicrobials in Bhutan and identify areas for improvement to reduce the use of antimicrobials in livestock. National data on livestock numbers and annual procurement of veterinary antimicrobials over five years (2017-2021) were used to calculate rates of antimicrobial consumption and annual national expenditure on veterinary antimicrobials in Bhutan. The rate of antimicrobial consumption in Bhutan was 3.83 mg per population correction unit, which is lower than most countries in Europe, comparable with the rates of consumption in Iceland and Norway, and approximately 120-fold lower than published rates of antimicrobial consumption in South Asian countries, including Nepal and Pakistan. The low rates of antimicrobial consumption by the animal health sector in Bhutan could be attributable to stronger governance of antimicrobial use in Bhutan, higher levels of compliance with regulation, and better adherence to standard guidelines for antimicrobial treatment of livestock.

3.
Pathogens ; 10(3)2021 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-33799817

RESUMO

The present research shows the results of a national study documenting the occurrence and genetic diversity of Echinococcus and Taenia species across Bhutan. Environmental dog faecal samples (n = 953) were collected from 2016 to 2018 in all 20 Bhutanese districts, mainly in urbanised areas. Cystic echinococcosis cysts were isolated from 13 humans and one mithun (Bos frontalis). Isolation of taeniid eggs from faeces was performed by sieving/flotation technique, followed by DNA isolation, PCR and sequence analyses for species identification (gene target: small subunit of ribosomal RNA). Genetic diversity of E. granulosuss.s. was based on the sequence (1609 bp) of the cox1 gene. A total of 67 out of 953 (7%) dog faecal samples were positive for at least one taeniid species. From the 670 free-roaming dog faecal samples, 40 (5.9%) were positive for taeniid DNA, 22 (3.2%) of them were identified as E. granulosuss.s. and four (0.5%) as E. ortleppi (G5). From the 283 faecal samples originating from yak-grazing areas, 27 (9.5%) were taeniid positive, including eight (2.8%) infected with E. granulosuss.s. and four (1.4%) with E. ortleppi. E. granulosuss.s. was identified in all isolates from human and the cyst from mithun. A haplotype network (cox1 gene) from E. granulosuss.s, including isolates from 12 dogs, two human and one mithun, revealed eight different haplotypes. The most common cox1 haplotype was the globally distributed Eg01, followed by Eg40 and Eg37 (previously described in China). Five new cox1 haplotypes (EgBhu1-5) originated from human, dogs, and a mithun were identified. The study indicated the contamination of urban areas and pastures with Echinococcus eggs in seven districts in Bhutan. The molecular characterisation of E. granulosuss.l. revealed different E. granulosuss.s. haplotypes as well as E. ortleppi. The transmission of T. multiceps was documented only in the western part of the country. Considering the zoonotic feature of E. granulosus s.s. and E. ortleppi and the economic impact of coenurosis caused by T. multiceps (also known as gid) in Bhutan, the findings of this study represent a significant contribution towards an epidemiological baseline for the establishment of a national control programme.

4.
Trop Med Infect Dis ; 6(1)2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33669524

RESUMO

Tick infestation is the most reported parasitological problem in cattle in Bhutan. In May and June 2019, we collected ticks from 240 cattle in two districts of Eastern Bhutan. Tick presence, diversity, and infestation prevalence were examined by morphological identification of 3600 live adult ticks. The relationships between cattle, geographic factors, and infestation prevalence were assessed using logistic regression analyses. Habitat suitability for the tick species identified was determined using MaxEnt. Four genera and six species of ticks were found. These were Rhipicephalus microplus (Canestrini) (70.2% (95% confidence interval (CI): 68.7-71.7)), Rhipicephalus haemaphysaloides Supino (18.8% (95% CI: 17.5-20.1)), Haemaphysalis bispinosa Neumann (8.2% (95% CI: 7.3-9.1)), Haemaphysalis spinigera Neumann (2.5% (95% CI: 2-3)), Amblyomma testudinarium Koch (0.19% (95% CI: 0.07-0.4)), and a single unidentified Ixodes sp. Logistic regression indicated that the variables associated with infestation were: longitude and cattle age for R. microplus; latitude for R. haemaphysaloides; and altitude and cattle breed for H. bispinosa and H. spinigera. MaxEnt models showed land cover to be an important predictor for the occurrence of all tick species examined. These findings provide information that can be used to initiate and plan enhanced tick surveillance and subsequent prevention and control programs for ticks and tick-borne diseases in cattle in Bhutan.

5.
PLoS One ; 16(2): e0247302, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33617588

RESUMO

Livestock farming plays an important role in supporting the livelihood of resource-poor subsistence farmers in Bhutan. However, ticks and tick-borne diseases (TBDs) are one of the major constraints to livestock farming due to their negative effect on health and production. To date, no study has been conducted in Bhutan to assess farmers' knowledge, attitude, and practices (KAP) about ticks and TBDs in cattle, although such information is essential in ensuring the development and adoption of effective prevention and control measures. Therefore, a KAP survey was conducted among 246 cattle owners in the Samkhar sub-district of eastern Bhutan in June 2019, using a structured questionnaire. Based on our scoring criteria, 52% [95%CI: 45.5-58.4] had adequate knowledge about ticks as potential vectors of diseases. Logistic regression analysis showed that the individuals who practiced a stall-feeding system of cattle rearing were 2.8 times [OR = 2.8 (95%CI: 1.66-4.78)] more likely to have adequate knowledge than others. Sixty-eight percent [95%CI: 62.5-74.4] had a favorable attitude toward tick prevention and control programs. Men were 1.95 times [OR = 1.95 (95%CI: 1.09-3.55)] more likely to have a favorable attitude than women, and the individuals who practiced a stall-feeding system were 2.59 times [OR = 2.59 95%CI: 1.45-4.78)] more likely to have a favorable attitude than others, after adjusting for the effect of other variables in the model. Overall, only 38% [95%CI 32.5-45] of the respondents reported tick infestation as one of the most important animal health problems, but 100% reported using acaricides to control ticks in cattle. Despite a high level of acaricide usage, the level of knowledge was low among the farmers interviewed. Findings from this study underline the importance of considering identified knowledge gaps and initiating education efforts to improve the adoption of effective tick prevention and control measures among farmers.


Assuntos
Fazendeiros/estatística & dados numéricos , Controle de Ácaros e Carrapatos/estatística & dados numéricos , Doenças Transmitidas por Carrapatos/prevenção & controle , Acaricidas/farmacologia , Adolescente , Adulto , Animais , Butão , Bovinos , Doenças dos Bovinos/prevenção & controle , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Infestações por Carrapato/prevenção & controle , Infestações por Carrapato/veterinária , Doenças Transmitidas por Carrapatos/veterinária , Carrapatos/efeitos dos fármacos , Adulto Jovem
6.
Transbound Emerg Dis ; 68(4): 1835-1849, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33058533

RESUMO

Remote and rural communities in low- and middle-income countries (LMICs) are disproportionately affected by infectious animal diseases due to their close contact with livestock and limited access to animal health personnel). However, animal disease surveillance and diagnosis in LMICs is often challenging, and turnaround times between sample submission and diagnosis can take days to weeks. This diagnostic gap and subsequent disease under-reporting can allow emerging and transboundary animal pathogens to spread, with potentially serious and far-reaching consequences. Point-of-care tests (POCTs), which allow for rapid diagnosis of infectious diseases in non-laboratory settings, have the potential to significantly disrupt traditional animal health surveillance paradigms in LMICs. This literature review sought to identify POCTs currently available for diagnosing infectious animal diseases and to determine facilitators and barriers to their use and uptake in LMICs. Results indicated that some veterinary POCTs have been used for field-based animal disease diagnosis in LMICs with good results. However, many POCTs target a small number of key agricultural and zoonotic animal diseases, while few exist for other important animal diseases. POCT evaluation is rarely taken beyond the laboratory and into the field where they are predicted to have the greatest impact, and where conditions can greatly affect test performance. A lack of mandated test validation regulations for veterinary POCTs has allowed tests of varying quality to enter the market, presenting challenges for potential customers. The use of substandard, improperly validated or unsuitable POCTs in LMICs can greatly undermine their true potential and can have far-reaching negative impacts on disease control. To successfully implement novel rapid diagnostic pathways for animal disease in LMICs, technical, regulatory, socio-political and economic challenges must be overcome, and further research is urgently needed before the potential of animal disease POCTs can be fully realized.


Assuntos
Doenças dos Animais , Doenças Transmissíveis , Doenças dos Animais/diagnóstico , Doenças dos Animais/epidemiologia , Animais , Doenças Transmissíveis/diagnóstico , Doenças Transmissíveis/epidemiologia , Doenças Transmissíveis/veterinária , Países em Desenvolvimento , Sistemas Automatizados de Assistência Junto ao Leito , Testes Imediatos , Zoonoses/diagnóstico
7.
BMC Vet Res ; 16(1): 183, 2020 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-32513172

RESUMO

BACKGROUND: Rabies kills approximately 59,000 people each year worldwide. Rapid and accurate diagnosis of rabies is important for instituting rapid containment measures and for advising the exposed people for postexposure treatment. The application of a rapid diagnostic tests in the field can greatly enhance disease surveillance and diagnostic activities, especially in resource poor settings. In this study, a total of 179 brain tissue samples collected from different rabies suspect animal species (113 dogs, 50 cattle, 10 cats, 3 goats, 2 horses, and 1 bear) were selected and tested using both rapid immunochromatographic kit and the reference standard fluorescent antibody test (FAT). We evaluated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of a rapid antigen detection test kit produced by BioNote, Inc. (Hwaseong-si, Korea) relative to a FAT for its fit-for-purpose for confirmation of clinical cases of rabies for early response and enhancing rabies surveillance. RESULTS: Among 179 samples examined in this study, there was a concordance in results by the rapid test and FAT in 115 positive samples and 54 negative samples. Test results were discordant in 10 samples which were positive by FAT, but negative (false negative) by rapid kit. The rapid test kit showed a sensitivity of 92% (95% CI: 85.9-95.6) and specificity of 100% (95% CI: 93.4-100) using FAT as the reference standard. The positive and negative predictive values were found to be 100% (95% CI:96.7-100) and 84.4% (95% CI: 73.6-91.3), respectively. Overall, there was 94.4% (95% CI: 90-96.9) test agreement between rapid test and FAT (Kappa value = 0.874) with a positive percent agreement and negative percent agreement of 92 and 100%, respectively. CONCLUSIONS: Our finding demonstrated that the rapid test kit (BioNote) can be used for rabies surveillance and confirming clinical case of rabies in animals for making rapid decisions particularly controlling rabies outbreaks in resource poor settings.


Assuntos
Cromatografia de Afinidade/veterinária , Testes Imunológicos/veterinária , Vírus da Raiva/isolamento & purificação , Raiva/veterinária , Animais , Antígenos Virais , Butão , Encéfalo/virologia , Cromatografia de Afinidade/métodos , Testes Diagnósticos de Rotina/veterinária , Imunofluorescência/veterinária , Testes Imunológicos/métodos , Mamíferos , Raiva/diagnóstico , Vírus da Raiva/imunologia , Sensibilidade e Especificidade
8.
Transbound Emerg Dis ; 67(6): 2494-2506, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32311239

RESUMO

Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hooved animals. Global outbreaks have highlighted the significant economic, trade, psychosocial and animal welfare impacts that can arise from the detection of disease in previously 'FMD-free' countries. Rapid and early diagnosis provides significant advantages in disease control and minimization of deleterious consequences. We describe the process of further development and validation of a reverse-transcription loop-mediated isothermal amplification foot-and-mouth disease virus (RT-LAMP-FMDV) test, using a published LAMP primer set, for use in the field. An internal positive control (IPC) was designed and introduced for use with the assay to mitigate any intrinsic interference from the unextracted field samples and avoid false negatives. Further modifications were included to improve the speed and operability of the test, for use by non-laboratory trained staff operating under field conditions, with shelf-stable reaction kits which require a minimum of liquid handling skills. Comparison of the assay performance with an established laboratory-based real-time reverse transcriptase PCR (rRT-PCR) test targeting the 3D region of FMD virus (Tetracore Inc) was investigated. LAMP has the potential to complement current laboratory diagnostics, such as rRT-PCR, as a preliminary tool in the investigation of FMD. We describe a strategic approach to validation of the test for use in the field using extracted RNA samples of various serotypes from Thailand and then finally unextracted field samples collected from FMD-suspected animals (primarily oral lesion swabs) from Bhutan and Australia. The statistical approach to validation was performed by Frequentist and Bayesian latent class methods, which both confirmed this new RT-LAMP-FMDV test as fit-for-purpose as a herd diagnostic tool with diagnostic specificity >99% and sensitivity 79% (95% Bayesian credible interval: 65, 90%) on unextracted field samples (oral swabs).


Assuntos
Vírus da Febre Aftosa/isolamento & purificação , Febre Aftosa/diagnóstico , Técnicas de Diagnóstico Molecular/veterinária , Técnicas de Amplificação de Ácido Nucleico/veterinária , Animais , Austrália , Teorema de Bayes , Butão , Febre Aftosa/virologia , Vírus da Febre Aftosa/genética , Sensibilidade e Especificidade , Tailândia
9.
Vet Med Sci ; 4(4): 288-295, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29974632

RESUMO

Johne's disease is an economically important ruminant disease predominantly affecting cattle, sheep and goats. The economic losses are due to early culling, reduced growth rate, progressive weight loss and reduced production. It is caused by Mycobacterium avium subspecies paratuberculosis (MAP). Johne's disease was reported in cattle in Bhutan, based on clinical signs and histopathology; in the late 1990s samples from one mithun that was suspected to have died due to this disease was confirmed by molecular testing at the Faculty of Veterinary Science, University of Sydney, Australia. However, no detailed study on prevalence of JD has been attempted in Bhutan. Objective of this study was to conduct serosurveillance to determine the national prevalence of Johne's disease in cattle for the period 2013-2014 to provide the basis for planning a future control strategy. A national serosurvey was conducted wherein a two-stage sampling procedure was used with 95% confidence and an error level of ±0.05. The sample size required for the survey was calculated using the software-Survey Toolbox for Livestock Diseases, available as Epitools at http://www.ausvet.com.au. A total of 1123 serum samples were collected from an administrative structure of 52 villages, 40 sub-districts and 15 districts. Serum samples were tested using commercially available antibody enzyme linked immunosorbent assay. Statistical analysis was performed using GraphPad Prism 5.0. Illustration such as maps was produced using QGIS version 2.18 'Las Palmas. The mean national apparent prevalence of Johne's disease was found to be 2.31 (26/1123) (95% CI: 0.80-4.50) with an estimated true prevalence was found to be 8.00 (95% CI: 2.00-17.00). Trongsa district had the highest prevalence (12.96) followed by Zhemgang (4.34), Lhuntse (4.25), Sarpang (3.89), Bumthang (3.60), Trashigang (2.67) and Haa (2.63). Prevalence for all other districts was 2.00 or below. Seropositive samples were reported from all over the country with varying levels of sero-positivity. In the recent past many more cattle were imported from India to boost dairy production. Nevertheless, the wide distribution of seroreactive JD cattle all over the country is a concern for future control. Therefore, in future, a detailed study on the impact of cattle import with regard to disease incursion such as Johne's disease and other diseases should be undertaken.


Assuntos
Doenças dos Bovinos/microbiologia , Mycobacterium avium subsp. paratuberculosis/imunologia , Paratuberculose/epidemiologia , Animais , Anticorpos Antibacterianos/sangue , Butão/epidemiologia , Bovinos , Doenças dos Bovinos/epidemiologia , Paratuberculose/microbiologia , Prevalência , Estudos Soroepidemiológicos
10.
Parasitol Int ; 66(2): 139-141, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28025118

RESUMO

In this pilot study, fecal samples were collected from community dogs around slaughterhouses and from the city of Thimphu (n=138) as well as from carnivores in the forest area around a farm in Bhutan (n=28). Samples were analyzed microscopically for the presence of taeniid eggs by the floatation and sieving method. Further molecular analyses of 20 samples of community dogs positive for taeniid eggs confirmed 10 Echinococcus granulosus sensu lato and one Taenia hydatigena case. From 14 environmental fecal samples from the forest area positive for taeniid eggs, one contained E. granulosus s.l., six T. hydatigena and one Taenia taeniaeformis DNA. In the remaining samples considered positive for taeniid eggs, no molecular confirmation could be achieved. Additionally, Echinococcus cysts were collected from locally slaughtered cattle and imported cattle organs. Seven Echinococcus cysts (one fertile) from the local animals and 35 (four fertile) from imported cattle organs were confirmed as E. granulosus (G1-3) by PCR/sequencing. One Echinococcus cyst each from a local animal and from an imported cattle organ (both fertile) were confirmed to be Echinococcus ortleppi (G5). Sterile Echinococcus cysts were also collected from local yaks (n=10), and all revealed to be E. granulosus (G1-G3). Hospital records of cystic echinococcosis in humans and the presence of Echinococcus spp. in dogs and ungulates indicate the existence of local transmission for both E. ortleppi and E. granulosus in Bhutan.


Assuntos
Doenças dos Bovinos/transmissão , Bovinos/parasitologia , Doenças do Cão/transmissão , Cães/parasitologia , Equinococose/veterinária , Echinococcus/isolamento & purificação , Matadouros , Animais , Butão/epidemiologia , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Doenças do Cão/epidemiologia , Doenças do Cão/parasitologia , Equinococose/epidemiologia , Equinococose/parasitologia , Equinococose/transmissão , Echinococcus/genética , Echinococcus granulosus/genética , Echinococcus granulosus/isolamento & purificação , Fazendas , Fezes/parasitologia , Genótipo , Humanos , Estágios do Ciclo de Vida/genética , Projetos Piloto , Reação em Cadeia da Polimerase/veterinária , Análise de Sequência de DNA , População Urbana
11.
Artigo em Inglês | MEDLINE | ID: mdl-25077074

RESUMO

Control of Johne's disease, caused by Mycobacterium avium subspecies paratuberculosis (MAP) in ruminants using commercially available vaccine reduces production losses, mortality, fecal shedding and histopathological lesions but does not provide complete protection from infection and interferes with serological diagnosis of Johne's disease and bovine tuberculosis. At this time no recombinant antigens have been found to provide superior protection compared to whole killed or live-attenuated MAP vaccines. Therefore, there is a need to evaluate more candidate MAP antigens. In this study recombinant MAP antigens MAP2698c and MAP3567 were formulated with four different MONTANIDE™ (ISA 50V2, 61VG, 71VG, and 201VG) adjuvants and evaluated for their ability to produce specific immune responses in vaccinated sheep. The cellular immune response was measured with an interferon-gamma (IFN-γ) release assay and the humoral immune response was measured by antibody detection enzyme linked immunosorbent assay. Recombinant vaccine formulation with the antigen MAP2698c and MONTANIDE™ ISA 201VG adjuvant produced strong whole-MAP as well as MAP2698c-specific IFN-γ responses in a high proportion of the vaccinated sheep. The formulation caused less severe injection site lesions in comparison to other formulations. The findings from this study suggest that the MAP2698c + 201VG should be evaluated in a challenge trial to determine the efficacy of this vaccine candidate.


Assuntos
Antígenos de Bactérias/imunologia , Vacinas Bacterianas/imunologia , Imunidade Celular , Imunidade Humoral , Mycobacterium avium subsp. paratuberculosis/imunologia , Paratuberculose/imunologia , Animais , Anticorpos Antibacterianos/sangue , Anticorpos Antibacterianos/imunologia , Vacinas Bacterianas/administração & dosagem , Ensaio de Imunoadsorção Enzimática , Interferon gama/biossíntese , Testes de Liberação de Interferon-gama , Ovinos , Vacinação
12.
Vet Immunol Immunopathol ; 160(1-2): 129-32, 2014 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-24788024

RESUMO

Evasion of host defense mechanisms and survival inside infected host macrophages are features of pathogenic mycobacteria including Mycobacterium avium subspecies paratuberculosis, the causative agent of Johne's disease in ruminants. Protein tyrosine phosphatase A (PtpA) has been identified as a secreted protein critical for survival of mycobacteria within infected macrophages. The host may mount an immune response to such secreted proteins. In this study, the humoral immune response to purified recombinant M. avium subsp. paratuberculosis PtpA was investigated using sera from a cohort of sheep infected with M. avium subsp. paratuberculosis and compared with uninfected healthy controls. A significantly higher level of reactivity to PtpA was observed in sera collected from M. avium subspecies paratuberculosis infected sheep when compared to those from uninfected healthy controls. PtpA could be a potential candidate antigen for detection of humoral immune responses in sheep infected with M. avium subspecies paratuberculosis.


Assuntos
Regulação Enzimológica da Expressão Gênica/imunologia , Mycobacterium avium subsp. paratuberculosis , Paratuberculose/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Doenças dos Ovinos/enzimologia , Animais , Estudos de Casos e Controles , Ensaio de Imunoadsorção Enzimática/veterinária , Paratuberculose/imunologia , Paratuberculose/microbiologia , Proteínas Tirosina Fosfatases/genética , Ovinos , Doenças dos Ovinos/imunologia , Doenças dos Ovinos/microbiologia
13.
Clin Vaccine Immunol ; 21(6): 831-7, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24695774

RESUMO

Johne's disease in ruminants is a chronic infection of the intestines caused by Mycobacterium avium subsp. paratuberculosis. An important strategy to control disease is early detection, and a potentially efficient method for early detection is measurement of cell-mediated immune responses developed by the host in response to exposure or infection. One method is to measure lymphoproliferation and cytokine release from the host cells when exposed to the organism or parts of the organism. In this study, 10 recombinant M. avium subsp. paratuberculosis proteins known to be upregulated under in vitro stress conditions were evaluated by examining their ability to evoke memory as a result of exposure by vaccination or oral challenge with live Mycobacterium avium subsp. paratuberculosis. Out of 10 proteins, MAP2698c was found to induce higher cell-mediated immune responses in vaccinated and challenged sheep in comparison to healthy controls. The findings suggest that not all stress-regulated proteins have the diagnostic potential to detect cell-mediated immune responses in ovine paratuberculosis.


Assuntos
Proteínas de Choque Térmico/imunologia , Interferon gama/sangue , Ativação Linfocitária/imunologia , Paratuberculose/diagnóstico , Doenças dos Ovinos/diagnóstico , Animais , Proteínas de Bactérias/imunologia , Proliferação de Células , Diagnóstico Precoce , Citometria de Fluxo/veterinária , Imunidade Celular , Linfócitos/imunologia , Mycobacterium avium subsp. paratuberculosis/imunologia , Paratuberculose/imunologia , Proteínas Recombinantes/imunologia , Ovinos , Doenças dos Ovinos/microbiologia
14.
Vet Immunol Immunopathol ; 158(1-2): 46-52, 2014 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-23815825

RESUMO

Serum antibody enzyme-linked immunosorbent assay is the most commonly used test for diagnosis of Mycobacterium avium subsp. paratuberculosis infection in ruminants. However, the assay requires serum preabsorption with Mycobacterium phlei proteins to reduce cross reactions potentially contributed by the exposure of livestock to environmental mycobacteria. To trial the discovery of novel antigens which do not require serum absorption, synthetic MAP-specific peptides were selected based on in silico research to identify putative B cell epitopes. Four peptides from previously identified stress-regulated proteins were synthesized and evaluated using enzyme linked immunosorbent assay to detect Mycobacterium avium subsp. paratuberculosis specific antibodies in sheep. Two peptides were from hypothetical MAP proteins (MAP3567 and MAP1168c) and two were from proteins with known function (MAP2698c, an acyl-acyl carrier protein desaturase-DesA2 and MAP2487c a carbonic anhydrase). The ability of each peptide to discriminate between unexposed and MAP exposed (infected and vaccinated) animals was similar to that of the parent recombinant MAP antigen, with area under receiver operating curve values of 0.86-0.93. Assays run with a combination of two peptides showed slightly higher reactivity than those of individual peptides. Peptides evaluated in this study had diagnostic potential similar to corresponding recombinant proteins but not superior to a complex native MAP antigen or a commercial assay. Further study is required to investigate other peptides for their diagnostic potential, and this may be simpler and cheaper than subunit protein-based research.


Assuntos
Anticorpos Antibacterianos/sangue , Antígenos de Bactérias , Epitopos de Linfócito B , Mycobacterium avium subsp. paratuberculosis/imunologia , Paratuberculose/microbiologia , Doenças dos Ovinos/microbiologia , Animais , Antígenos de Bactérias/genética , Área Sob a Curva , Ensaio de Imunoadsorção Enzimática/veterinária , Epitopos de Linfócito B/genética , Mycobacterium avium subsp. paratuberculosis/genética , Paratuberculose/sangue , Paratuberculose/imunologia , Projetos Piloto , Reprodutibilidade dos Testes , Ovinos , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/imunologia
15.
Clin Vaccine Immunol ; 20(12): 1817-26, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24132604

RESUMO

Mycobacterium avium subsp. paratuberculosis causes Johne's disease (JD) in ruminants. Proteomic studies have shown that M. avium subsp. paratuberculosis expresses certain proteins when exposed to in vitro physiological stress conditions similar to the conditions experienced within a host during natural infection. Such proteins are hypothesized to be expressed in vivo, are recognized by the host immune system, and may be of potential use in the diagnosis of JD. In this study, 50 recombinant maltose binding protein (MBP)-M. avium subsp. paratuberculosis fusion proteins were evaluated using serum samples from sheep infected with M. avium subsp. paratuberculosis, and 29 (58%) were found to be antigenic. Among 50 fusion proteins, 10 were evaluated in MBP fusion and factor Xa-cleaved forms. A total of 31 proteins (62%) were found to be antigenic in either MBP fusion or factor Xa-cleaved forms. Antigenicity after cleavage and removal of the MBP tag was marginally enhanced.


Assuntos
Ensaio de Imunoadsorção Enzimática/veterinária , Proteínas Ligantes de Maltose/imunologia , Paratuberculose/imunologia , Proteínas Recombinantes de Fusão/imunologia , Doenças dos Ovinos/imunologia , Animais , Anticorpos Antibacterianos/imunologia , Antígenos de Bactérias/imunologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Fator Xa/metabolismo , Proteínas Ligantes de Maltose/sangue , Mycobacterium avium subsp. paratuberculosis/imunologia , Ovinos/sangue , Ovinos/microbiologia , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/microbiologia
16.
Vet Immunol Immunopathol ; 149(3-4): 186-96, 2012 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-22868202

RESUMO

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne's disease (JD) in ruminants. MAP is known to enter a dormant phase outside the host, typically on soil. In vitro experiments have reported regulation of certain MAP genes when exposed to stressors similar to what is thought to produce dormancy. It is believed that in vivo regulation of dormancy genes and associated proteins by MAP may play a role in evading the host defence mechanisms and induce the host immune response against these dormancy-related proteins. Five proteins encoded by dormancy-related genes that were previously found to be upregulated under stress conditions and predicted through in silico analysis to possess immune epitopes (three hypothetical proteins and two proteins involved in fatty acid metabolism) were selected. Recombinant proteins were produced, purified and evaluated by indirect enzyme-linked immunosorbent assay (ELISA) for immunogenicity using a panel of sera obtained from sheep unexposed and exposed to MAP. The antibody levels of the exposed group were significantly higher than the unexposed group (P<0.001). Individually, the five proteins were found to discriminate between sera from sheep exposed to MAP compared to unexposed sheep. At 91% diagnostic specificity, the diagnostic sensitivity of the recombinant antigen ELISA ranged from 24% to 42% and AUC(ROC) from 0.7015 to 0.8405.


Assuntos
Proteínas de Bactérias/imunologia , Mycobacterium avium subsp. paratuberculosis/imunologia , Paratuberculose/imunologia , Doenças dos Ovinos/imunologia , Doenças dos Ovinos/microbiologia , Animais , Anticorpos Antibacterianos/sangue , Área Sob a Curva , Proteínas de Bactérias/genética , Ensaio de Imunoadsorção Enzimática/veterinária , Imunidade Humoral/imunologia , Paratuberculose/microbiologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Sensibilidade e Especificidade , Ovinos , Regulação para Cima/imunologia
17.
Clin Vaccine Immunol ; 19(6): 855-64, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22496492

RESUMO

Johne's disease in ruminants is caused by Mycobacterium avium subsp. paratuberculosis. Diagnosis of M. avium subsp. paratuberculosis infection is difficult, especially in the early stages. To date, ideal antigen candidates are not available for efficient immunization or immunodiagnosis. This study reports the in silico selection and subsequent analysis of epitopes of M. avium subsp. paratuberculosis proteins that were found to be upregulated under stress conditions as a means to identify immunogenic candidate proteins. Previous studies have reported differential regulation of proteins when M. avium subsp. paratuberculosis is exposed to stressors which induce a response similar to dormancy. Dormancy may be involved in evading host defense mechanisms, and the host may also mount an immune response against these proteins. Twenty-five M. avium subsp. paratuberculosis proteins that were previously identified as being upregulated under in vitro stress conditions were analyzed for B and T cell epitopes by use of the prediction tools at the Immune Epitope Database and Analysis Resource. Major histocompatibility complex class I T cell epitopes were predicted using an artificial neural network method, and class II T cell epitopes were predicted using the consensus method. Conformational B cell epitopes were predicted from the relevant three-dimensional structure template for each protein. Based on the greatest number of predicted epitopes, eight proteins (MAP2698c [encoded by desA2], MAP2312c [encoded by fadE19], MAP3651c [encoded by fadE3_2], MAP2872c [encoded by fabG5_2], MAP3523c [encoded by oxcA], MAP0187c [encoded by sodA], and the hypothetical proteins MAP3567 and MAP1168c) were identified as potential candidates for study of antibody- and cell-mediated immune responses within infected hosts.


Assuntos
Proteínas de Bactérias/imunologia , Epitopos/imunologia , Mycobacterium avium subsp. paratuberculosis/imunologia , Animais , Proteínas de Bactérias/genética , Epitopos/genética , Perfilação da Expressão Gênica , Mycobacterium avium subsp. paratuberculosis/genética , Paratuberculose/diagnóstico , Paratuberculose/imunologia , Conformação Proteica , Estresse Fisiológico
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...