College of Animal Science & Technology, Shihezi University, Shihezi, Xinjiang Province, People's Republic of China ; Department of Rickettsiology, National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, People's Republic of China.
PLoS One. 2013 Oct 22;8(10):e78189. doi: 10.1371/journal.pone.0078189. eCollection 2013.
Molecular characterization of the MSP2/P44 protein of Anaplasma phagocytophilum may determine not only if the bacterium is capable of invading hosts but also whether it generates antigenic variation for the purpose of escaping the host immune response, resulting in various pathologic injuries and serious clinical outcomes. Chinese anaplasmosis patients usually present with serious manifestations, and the fatality rate is as high as 26.5%. In this study, we amplified, cloned and sequenced the msp2/p44 genes of three Chinese A. phagocytophilum isolates from Laizhou Bay, Shandong Province, where human granulocytic anaplasmosis (HGA) patients present severe clinical manifestations, and analyzed their genetic characterization and structural features. We also compared them with the HZ and Webster A. phagocytophilum strains. The sequences for both strains are available in GenBank. Analyses indicated that Chinese A. phagocytophilum isolates were significantly different from the HZ and Webster strains in terms of nucleotide sequences, amino acid sequences and protein secondary and tertiary structures. Moreover, the number of immunologic B-cell epitopes (19) of the MSP2 protein of the Chinese isolates was higher than that of the A. phagocytophilum strains HZ (16) and Webster (9). This genetic diversity of the MSP2/P44 protein of Chinese A. phagocytophilum isolates might be relevant and might have serious clinical outcomes. This observation could provide a clue to further understand the pathogenesis of Chinese A. phagocytophilum.
嗜吞噬细胞无形体 MSP2/P44 蛋白的分子特征不仅决定了细菌是否能够侵入宿主，还决定了其是否为逃避宿主免疫反应而产生抗原变异，从而导致各种病理损伤和严重的临床后果。中国无形体病患者通常表现出严重的症状，死亡率高达 26.5%。在这项研究中，我们扩增、克隆和测序了来自山东省莱州湾的三株中国嗜吞噬细胞无形体分离株的 msp2/p44 基因，这些分离株与人类粒细胞无形体病（HGA）患者的严重临床表现有关，并分析了它们的遗传特征和结构特征。我们还将它们与 HZ 和 Webster 嗜吞噬细胞无形体株进行了比较。这两个菌株的序列都可在 GenBank 中获得。分析表明，中国嗜吞噬细胞无形体分离株在核苷酸序列、氨基酸序列和蛋白质二级、三级结构方面与 HZ 和 Webster 株有显著差异。此外，中国分离株 MSP2 蛋白的免疫 B 细胞表位（19 个）数量高于 HZ（16 个）和 Webster（9 个）株。中国嗜吞噬细胞无形体分离株 MSP2/P44 蛋白的这种遗传多样性可能与其严重的临床后果有关。这一观察结果可能为进一步了解中国嗜吞噬细胞无形体的发病机制提供线索。
