Influenza A virus infection engenders a poor antibody response against the ectodomain of matrix protein 2.
Influenza A virus infection engenders a poor antibody response against the ectodomain of matrix protein 2.
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DOI：
10.1186/1743-422x-3-102
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发表时间：
2006-12-06
期刊：
影响因子：
4.8
通讯作者：
Gerhard W
中科院分区：
文献类型：
--
作者：
Feng J;Zhang M;Mozdzanowska K;Zharikova D;Hoff H;Wunner W;Couch RB;Gerhard W
基质蛋白2(M 2)是甲型流感病毒(IAV)完整的四聚体膜蛋白。它的胞外区(M2e)在人IAV毒株之间显示出明显的很小的多样性。由于M2e特异性抗体(Abs)已被证明可以降低动物感染的严重程度，人们正在研究M2e对广泛的IAV毒株提供保护的能力。目前，关于人类体内M2e特异性抗体浓度的信息很少。以前的两项研究分别使用了针对M2e多肽和重组M2蛋白的ELISA法和Western印迹法作为免疫吸附剂，报告的抗体效价很低或检测不到。一个重要的警告是，这些分析可能没有检测到所有能够与天然四聚体M2e结合的抗体。因此，我们开发了一种可能检测所有M2e四聚体特异性抗体的方法。我们建立了一个在四环素反应元件控制下表达全长四聚体M2(HeLa-M2)或空载体(HeLa-C10)的HeLa细胞系。然后将这些细胞系平行用作免疫吸附材料进行ELISA法。用纯化的小鼠抗体和嵌合抗体(鼠可变区、人恒定区)分别测定小鼠和人血清中的M2e特异性抗体效价。我们发现，在检测反复感染IAV后康复的小鼠血清中的M2e特异性抗体时，基于细胞的ELISA法比固定化M2e肽更有效。尽管如此，即使在连续两次感染后，效价仍然很低(<；5μg/ml)，但在第三次感染后，效价上升到~50μg/ml。与游离M2e多肽的竞争表明，感染产生的M2e特异性抗体中约有20%与M2e多肽发生反应。在表现为自然获得性流感病毒感染的人类中，24对血清中有11对显示≥特异性M2e抗体效价增加4倍。抗体反应似乎持续时间很短，因为所有患者和对照组的抗体滴度在感染开始时都很低(平均为0.2μg/ml)，尽管有证据表明曾接触过IAV。这些结果提供了令人信服的证据，表明M2e特异性抗体介导的保护目前在人类中缺乏或不理想。
Matrix protein 2 (M2) is an integral tetrameric membrane protein of influenza A virus (IAV). Its ectodomain (M2e) shows remarkably little diversity amongst human IAV strains. As M2e-specific antibodies (Abs) have been shown to reduce the severity of infection in animals, M2e is being studied for its capability of providing protection against a broad range of IAV strains. Presently, there is little information about the concentration of M2e-specific Abs in humans. Two previous studies made use of ELISA and Western blot against M2e peptides and recombinant M2 protein as immunosorbents, respectively, and reported Ab titers to be low or undetectable. An important caveat is that these assays may not have detected all Abs capable of binding to native tetrameric M2e. Therefore, we developed an assay likely to detect all M2e tetramer-specific Abs. We generated a HeLa cell line that expressed full length tetrameric M2 (HeLa-M2) or empty vector (HeLa-C10) under the control of the tetracycline response element. These cell lines were then used in parallel as immunosorbents in ELISA. The assay was standardized and M2e-specific Ab titers quantified by means of purified murine or chimeric (mouse variable regions, human constant regions) M2e-specific Abs in the analysis of mouse and human sera, respectively. We found that the cell-based ELISA was substantially more effective than immobilized M2e peptide in detecting M2e-specific Abs in sera of mice that had recovered from repetitive IAV infections. Still, titers remained low (< 5 μg/ml) even after two consecutive infections but increased to ~50 μg/ml after the third infection. Competition with free M2e peptide indicated that ~20% of M2e-specific Abs engendered by infection reacted with M2e peptide. In humans presenting with naturally acquired influenza virus infection, 11 of 24 paired sera showed a ≥ 4-fold increase in M2e-specific Ab titer. The Ab response appeared to be of short duration as titers were very low (average 0.2 μg/ml) in all patients at onset of infection and in controls, in spite of evidence for previous exposure to IAV. The results provide convincing evidence that M2e-specific Ab-mediated protection is currently lacking or suboptimal in humans.