The M Protein of SARS-CoV: Basic Structural and Immunological Properties

Hu, Yongwu; Wen, Jie; Tang, Lin; Zhang, Haijun; Zhang, Xiaowei; Li, Yan; Wang, Jing; Han, Yujun; Li, Guoqing; Shi, Jianping; Tian, Xiangjun; Jiang, Feng; Zhao, Xiaoqian; Wang, Jun; Liu, Siqi; Zeng, Changqing; Wang, Jian; Yang, Huanming

At least eight predicted antigenic sites have been localized in this region. It has been postulated that these sites inside the virion might be related to the viral antigenicity after endocytosis when the virion is collapsed and the non-exterior regions of the M protein molecules are released into the host cytoplasm and exposed, or immediately after translation and subsequent modification before integrating into the host membranous components. The immunological results were generally consistent with the predicted antigenic regions and basic structure analysis of the M protein with bioinformatics tools. Four segments, 1-20, 137-157, 189-211, 206-221, were showed to react with antibodies of SARS patients. These segments, as predicted by bioinformatics tools, exhibit high hydrophilicity. The 1-20 segment is an exterior region, and the others are interior regions. The predicted TM region with high hydrophobicity was found to be non-immunoreactive experimentally, and our findings conformed well to results obtained by using bioinformatics tools.