前言

自結核桿菌發現至今，已有近140年歷史，但結核病仍然是對全球健康的重大威脅，是導致死亡的主要原因，特別是在發展中國家。由于結核病全球死亡率與艾滋病并列第一，大多數國家都在響應世衛組織“2035年結束結核病戰略”。

作為一個結核病負擔高的國家，中國開發了新的工具，特別是在結核病診斷方面，以減少結核病的流行。目前方法并不優于結核菌素皮膚試驗，也不能區分潛在結核桿菌感染和活動性結核且漏診率較高，僅60%~80%的活動性肺結核可采用現有的診斷方法檢出。

因此，識別新的宿主和病原體的生物標志物是提高結核病診斷準確性的關鍵。最近，科學家們正致力于破譯每一種結核桿菌基因或蛋白質功能。在4，000多個結核桿菌開放閱讀框架(ORF)中，分泌蛋白(如ESAT-6、CFP-10和Ag85A/B)被認為能刺激抗原特異性免疫應答，并被廣泛用于診斷和疫苗研制。然而，這些蛋白質的使用仍然受到限制。

臨床上，因為它們不能用于結核病感染和結核病的鑒別診斷，只有70%的陽性臨床結核病患者被這些蛋白所識別。醫科院病原所金奇實驗室已對1250種蛋白質(約占結核桿菌蛋白的三分之一)的功能進行了全面的研究。

 結核桿菌膜蛋白抗原性研究 

醫科院病原所最近發表文章：Analysis of the Antigenic Properties of Membrane Proteins of Mycobacterium tuberculosis，(2019) 9:3042 | https://doi.org/10.1038/s41598-019-39402-z 1，集中研究結核桿菌膜蛋白。結合桿菌膜蛋白一直被認為是免疫原，是指與生物膜相互作用或構成生物膜的蛋白質，包括永久錨定或構成膜的完整膜蛋白，以及僅暫時附著在脂質雙層或其他整體蛋白質上的外周膜蛋白。

為了更好地了解這些蛋白，科學家表達并純化了所有結核桿菌膜蛋白，并通過三輪血清學免疫檢測來確定其作為潛在血清學診斷標志物的價值。此外，還進行了兩輪細胞免疫試驗，以評價這些蛋白質作為篩選生物標記物的適用性。進一步分析結核病患者細胞抗原反應所產生的膜蛋白抗原，可加速抗原生物標志物的研究，提高結核病診斷和疫苗的研制水平。

研究路線圖

Wes全自動定量western blot系統承擔了本研究最重要的血清抗原分析（219種結核桿菌膜蛋白病人血清結合實驗）

Identification of M. tb serological antigens by Western blotting.

Although humoural immunity remains an auxiliary means of diagnosing TB, we expected the results of Western blotting to provide us with useful M.tb-specific 6 antigens for serum IgG, as based on our previous method. Transmembrane proteins play important roles in the transport of substances and immune protection. To assess the antigenic properties of the induced humoral response in patients, Western Blotting was performed to identify serological antigens in pulmonary TB patients (Table 1) and healthy controls (Table 2). To avoid the influence of Bacillus Clamette- Guérin (BCG) vaccination, the healthy controls included individuals with or without a BCG vaccine scar. Additionally, a positive protein response to active pulmonary TB patient serum was used to screen control candidate serum (data not show). All serum samples were pretreated to remove the E. coli background as reported previously and bovine albumin (BSA) and commercial Rv0934 were used as the negative and positive control. To evaluate the antigenicity of each M.tb protein, the serum response intensity ratio of expression level of the target proteins to that of Rv0934 was calculated; if the ratio was equal to or greater than 1, the protein was confirmed in second and third rounds. After the first round of testing, we obtained positive responses for 161 of the 219 membrane protein candidates (approximately 74%). After the second round, 52 membrane proteins had a ratio greater than that of Rv0934 (Fig. 2, Supplemental Tables S1, Figs S2–S4); the yellow bars indicate positive proteins, and the ratio ranged from 0.02% to 338%. After three rounds, 18 of the remaining membrane proteins had ratios above 1, (Fig. 2, dark blue bars). The ratio of Rv1111c (427–981) was particularly high (a mean ratio at 3.38).