Assessment of antigenic supplementation of bovine purified protein derivative for diagnosis of subclinical infection with Mycobacterium bovis in cattle
Assessment of antigenic supplementation of bovine purified protein derivative for diagnosis of subclinical infection with Mycobacterium bovis in cattle
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DOI：
10.1016/j.micpath.2017.05.012
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发表时间：
2017-07-01
影响因子：
3.8
通讯作者：
Hinojoza-Loza, E.
中科院分区：
文献类型：
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作者：
Alvarez, A. H.;Gutierrez-Ortega, A.;Hinojoza-Loza, E.
牛结核（bTB）通常在体内和体外诊断的基础上延迟超敏反应与一个复杂的抗原池称为牛结核菌素（PPDB）。bTB的ifn - γ释放试验（IGRA）是一种基于血液的试验，可在逃避皮肤试验的早期阶段提高对感染牛的检测。改进的ifn - γ测试与特定的蛋白质进行，以提高灵敏度。DosR调控子相关抗原是众所周知的分枝杆菌蛋白，在感染的非复制阶段表达，这有助于提高对疑似个体的亚临床形式结核病的诊断。本课题组在ifn - γ检测阴性牛的淋巴结中发现了DosR基因mb2054c、mb2057c和mb2660c的转录本。这使我们假设dosr相关蛋白可能增强ifn - γ测试假阴性动物对PPDB的ifn - γ反应，导致明显的亚临床感染。通过IGRA和死后组织样本微生物学分析对300只动物进行评估，以验证牛支原体感染。我们发现300只动物中有176只与单独PPDB相比，用两种纯化蛋白鸡尾酒补充IGRA总体上增加了OD，并仔细检查了亚临床感染；当PPDB补充四种DosR抗原的鸡尾酒时为30%，当PPDB补充六种抗原的鸡尾酒（四种DosR和两种RD1抗原）时为70%。45只动物显示大量ifn - γ过量产生，但仍为阴性，40只动物将结果改为阳性测试。在176只ifn - γ高产动物中，只有18只对牛分枝杆菌分离呈阳性。57只在屠宰时无明显病变且IGRA检测结果为阴性的动物在组织样本中含有牛支原体DNA。综上所述，Mb1762c、Mb2054c、Mb2057c和Mb2660c添加PPDB后，具有提高体外ifn - γ检测bTB诊断敏感性的潜力。(C) 2017 Elsevier Ltd.版权所有。
Bovine tuberculosis (bTB) is usually diagnosed in vivo and ex vivo on the basis of delayed hypersensitivity reactions with a complex pool of antigens named bovine tuberculin (PPDB). The IFN-gamma release assay (IGRA) for bTB is a blood-based assay that improves detection of infected cattle at early stages that escape skin testing. Improvements to IFN-gamma testing with specific proteins have been performed to increase sensitivity. DosR regulon-related antigens are well known mycobacterial proteins expressed during the non-replicative phases of infection, this has been useful to improve the diagnosis of subclinical forms of TB in suspected individuals. Transcripts of DosR genes mb2054c, mb2057c, and mb2660c have been identified by our group in lymph nodes of IFN-gamma test negative cattle. This led us to hypothesize that DosR-related proteins may potentiate the IFN-gamma response to PPDB in animals with a false negative IFN-gamma test, making evident subclinical infection. Three hundred animals were evaluated by means of IGRA and postmortem microbiological analysis of tissue samples to validate M. bovis infection. We found that 176 out of 300 animals showed an overall increased OD in complemented IGRA with two purified protein cocktails in comparison to PPDB alone, and were scrutinized for a subclinical infection; thirty percent when PPDB was supplemented with a cocktail of four DosR antigens, and 70% when PPDB was supplemented with a cocktail of six antigens (four DosR and two RD1 antigens). Forty five animals showed a substantial IFN-gamma overproduction but remained negative, and 40 animals changed the result to a positive test. Only 18 out of 176 IFN-gamma high producing animals were also positive to M. bovis isolation. Fifty seven animals with no visible lesions at slaughter and with a negative IGRA test result contained M. bovis DNA in tissue samples. In conclusion, Mb1762c, Mb2054c, Mb2057c, and Mb2660c have the potential to increase sensitivity of the IFN-gamma in vitro test for bTB diagnosis when supplemented to PPDB. (C) 2017 Elsevier Ltd. All rights reserved.