Vordermeier H M, Whelan A, Cockle P J, Farrant L, Palmer N, Hewinson R G
TB Research Group, Department of Bacterial Diseases, Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone KT15 3NB, United Kingdom.
Clin Diagn Lab Immunol. 2001 May;8(3):571-8. doi: 10.1128/CDLI.8.3.571-578.2001.
In Great Britain an independent scientific review for the government has concluded that the development of a cattle vaccine against Mycobacterium bovis infection holds the best long-term prospect for tuberculosis control in British herds. A precondition for vaccination is the development of a complementary diagnostic test to differentiate between vaccinated animals and those infected with M. bovis so that testing and slaughter-based control strategies can continue alongside vaccination. To date bacillus Calmette-Guérin (BCG), an attenuated strain of M. bovis, is the only available vaccine for the prevention of tuberculosis. However, tests based on tuberculin purified protein derivative cannot distinguish between M. bovis infection and BCG vaccination. Therefore, specific antigens expressed by M. bovis but absent from BCG constitute prime candidates for differential diagnostic reagents. Recently, two such antigens, ESAT-6 and CFP-10, have been reported to be promising candidates as diagnostic reagents for the detection of M. bovis infection in cattle. Here we report the identification of promiscuous peptides of CFP-10 that were recognized by M. bovis-infected cattle. Five of these peptides were formulated into a peptide cocktail together with five peptides derived from ESAT-6. Using this peptide cocktail in T-cell assays, M. bovis-infected animals were detected, while BCG-vaccinated or Mycobacterium avium-sensitized animals did not respond. The sensitivity of the peptide cocktail as an antigen in a whole-blood gamma interferon assay was determined using naturally infected field reactor cattle, and the specificity was determined using blood from BCG-vaccinated and noninfected, nonvaccinated animals. The sensitivity of the assay in cattle with confirmed tuberculosis was found to be 77.9%, with a specificity of 100% in BCG-vaccinated or nonvaccinated animals. This compares favorably with the specificity of tuberculin when tested in noninfected or vaccinated animals. In summary, our results demonstrate that this peptide cocktail can discriminate between M. bovis infection and BCG vaccination with a high degree of sensitivity and specificity.
在英国，一项为政府开展的独立科学评估得出结论：研发针对牛分枝杆菌感染的牛用疫苗是英国牛群结核病防控的最佳长期前景。疫苗接种的一个前提条件是开发一种辅助诊断检测方法，以区分接种疫苗的动物和感染牛分枝杆菌的动物，这样基于检测和屠宰的防控策略就能与疫苗接种同时继续实施。迄今为止，卡介苗（BCG），一种牛分枝杆菌的减毒株，是唯一可用于预防结核病的疫苗。然而，基于结核菌素纯化蛋白衍生物的检测无法区分牛分枝杆菌感染和卡介苗接种情况。因此，牛分枝杆菌表达但卡介苗不表达的特异性抗原成为鉴别诊断试剂的主要候选物。最近，据报道两种这样的抗原，ESAT - 6和CFP - 10，有望成为检测牛感染牛分枝杆菌的诊断试剂。在此我们报告了对CFP - 10的混杂肽段的鉴定，这些肽段能被感染牛分枝杆菌的牛识别。其中五个肽段与来自ESAT - 6的五个肽段一起配制成肽混合物。在T细胞检测中使用这种肽混合物，能检测出感染牛分枝杆菌的动物，而接种卡介苗或感染鸟分枝杆菌致敏的动物无反应。使用自然感染的现场反应牛测定该肽混合物作为全血γ干扰素检测中抗原的敏感性，并使用接种卡介苗以及未感染、未接种疫苗动物的血液测定其特异性。在确诊为结核病的牛中该检测的敏感性为77.9%，在接种卡介苗或未接种疫苗的动物中特异性为100%。与在未感染或接种疫苗动物中检测结核菌素的特异性相比，这一结果很有优势。总之，我们的结果表明这种肽混合物能够以高度的敏感性和特异性区分牛分枝杆菌感染和卡介苗接种情况。
