Quinn A, Ward K, Fischetti V A, Hemric M, Cunningham M W
Departments of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA.
Infect Immun. 1998 Sep;66(9):4418-24. doi: 10.1128/IAI.66.9.4418-4424.1998.
The class I epitope of streptococcal M protein is an epidemiological marker for acute rheumatic fever (ARF)-associated serotypes of group A streptococci and is recognized by anti-M protein monoclonal antibody (MAb) 10B6. Using MAb 10B6, we determined the relationship between the class I epitope of M protein and the alpha-helical coiled-coil protein myosin. MAb 10B6 reacted by enzyme-linked immunosorbent assay and Western blotting with human cardiac myosin and rabbit skeletal myosin and its heavy meromyosin (HMM) subfragment. Overlapping synthetic peptides of M5 protein were used to identify the region of M5 protein recognized by MAb 10B6. Two C repeat peptides (C2A and C3) containing the amino acid sequence KGLRRDLDASREAK reacted with MAb 10B6. Partial sequence identity, RRDL, was found in the HMM fragment of myosin, which reacted with MAb 10B6. However, not all peptides of M5 protein and myosin containing the RRDL sequence reacted with MAb 10B6. ARF sera and sera from uncomplicated pharyngitis (UNC) reacted with C repeat region peptides of M protein, while acute glomerulonephritis sera were not as reactive. Affinity-purified human antibody to peptide C3 reacted with myosin. The data demonstrate that the class I epitope of M protein is immunologically cross-reactive with myosin and the HMM subfragment, and antibodies to peptide C3 and myosin were present in ARF and UNC sera.
A群链球菌的I类表位是急性风湿热（ARF）相关血清型的流行病学标志物，可被抗M蛋白单克隆抗体（MAb）10B6识别。我们使用MAb 10B6确定了M蛋白的I类表位与α-螺旋卷曲螺旋蛋白肌球蛋白之间的关系。通过酶联免疫吸附测定和蛋白质印迹法，MAb 10B6与人心肌肌球蛋白、兔骨骼肌肌球蛋白及其重酶解肌球蛋白（HMM）亚片段发生反应。利用M5蛋白的重叠合成肽来鉴定被MAb 10B6识别的M5蛋白区域。两条含有氨基酸序列KGLRRDLDASREAK的C重复肽（C2A和C3）与MAb 10B6发生反应。在与MAb 10B6发生反应的肌球蛋白的HMM片段中发现了部分序列一致性RRDL。然而，并非所有含有RRDL序列的M5蛋白和肌球蛋白肽都能与MAb 10B6发生反应。ARF血清和单纯性咽炎（UNC）血清与M蛋白的C重复区域肽发生反应，而急性肾小球肾炎血清的反应性则较弱。亲和纯化的针对肽C3的人抗体与肌球蛋白发生反应。数据表明，M蛋白的I类表位与肌球蛋白和HMM亚片段存在免疫交叉反应，并且ARF和UNC血清中存在针对肽C3和肌球蛋白的抗体。
