Delayed type hypersensitivity (DTH) based skin test is an important onsite animal herd screening procedure for detecting the early stages of the chronic mycobacterial infections. DTH testing plays a vital role in the diagnosis of paratuberculosis infection. However, there are questions over the specificity of this test due to cross-reactive epitopes present on the purified protein derivative (PPD) prepared from the whole cell secretory proteins. PPD may contain proteins shared with other mycobacteria especially environmental species. Therefore, it is needed to test alternate paratuberculosis specific secretory antigens. Present study explored the potential of recombinant secretory proteins (MAP2168c, MAP1693c, MAP3547c, MAP4308c and MAP2677c) as DTH markers. The published literature shows that these proteins as strong cell mediated markers with specificity to paratuberculosis bacilli. To determine the positive skin thickness cutoff, herds of farm animals with history of endemic paratuberculosis were selected and thickness of >2.0 mm was reported as the positive cutoff. Preliminary findings on pilot scale animals report the usefulness of recombinant secretory proteins as DTH markers over traditional Johnin assay. Traditional Johnin reported more false positives and negatives compared to gold standard fecal PCR and field reference plate ELISA test. Present findings encourage and demand further research.

基于迟发型超敏反应（DTH）的皮肤测试是一种重要的现场动物群筛选程序，可用于检测慢性分枝杆菌感染的早期阶段。DTH测试在诊断副结核感染中起着至关重要的作用。但是，由于从全细胞分泌蛋白制备的纯化蛋白衍生物（PPD）上存在交叉反应性表位，因此该测试的特异性存在疑问。PPD可能包含与其他分枝杆菌（尤其是环境物种）共享的蛋白质。因此，需要测试替代性结核旁特异性分泌抗原。目前的研究探索了重组分泌蛋白（MAP2168c，MAP1693c，MAP3547c，MAP4308c和MAP2677c）作为DTH标记的潜力。已发表的文献表明，这些蛋白质是强力细胞介导的标记物，对结核菌副杆菌具有特异性。为了确定阳性皮肤厚度临界值，选择了具有地方性副肺结核病史的牲畜群，并报告厚度> 2.0 mm作为阳性临界值。中试规模动物的初步发现报告了重组分泌蛋白作为DTH标记物的作用，优于传统的Johnin测定法。与金标准粪便PCR和现场参考板ELISA试验相比，传统的Johnin报告了更多的假阳性和阴性。目前的发现鼓励并需要进一步的研究。据报道0mm为正截止值。中试规模动物的初步发现报告了重组分泌蛋白作为DTH标记物的作用，优于传统的Johnin测定法。与金标准粪便PCR和现场参考板ELISA试验相比，传统的Johnin报告了更多的假阳性和阴性。目前的发现鼓励并需要进一步的研究。据报道0mm为正截止值。中试规模动物的初步发现报告了重组分泌蛋白作为DTH标记物的作用，优于传统的Johnin测定法。与金标准粪便PCR和现场参考板ELISA试验相比，传统的Johnin报告了更多的假阳性和阴性。目前的发现鼓励并需要进一步的研究。