Shet Anita, Kaplan Edward, Johnson Dwight, Cleary Patrick Paul
Department of Pediatrics, World Health Organization Collaborating Center for Reference & Research on Streptococci, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
Indian J Med Res. 2004 May;119 Suppl:95-8.
BACKGROUND & OBJECTIVES: Group A streptococcal C5a peptidase (SCPA) is a major virulence surface factor. Its highly conserved nature among all tested serotypes of group A streptococci (GAS) as well as animal protection studies make SCPA a prime vaccine candidate. The present study was undertaken to explore the human immunogenicity to SCPA using an indirect enzyme-linked immunosorbent assay.
Children (n=72) who had signs and symptoms of acute pharyngitis and had GAS isolated from the throat at initial visit were included. Acute and convalescent sera were collected 4 weeks apart. ELISA was performed using recombinant SCPA peptide as antigen.
The mean convalescent anti-SCPA level was twice the level of mean acute anti-SCPA and the difference was statistically significant (P < 0.0001). There was a rise in convalescent anti-SCPA in all children aged 2-12 yr.
INTERPRETATION & CONCLUSION: Our observations confirmed that SCPA was highly immunogenic in children infected with group A streptococcal pharyngitis. Further studies need to be done to characterize the immune response including antibody subclass.
A 组链球菌 C5a 肽酶（SCPA）是一种主要的毒力表面因子。它在所有测试的 A 组链球菌（GAS）血清型中具有高度保守性，以及动物保护研究表明 SCPA 是主要的疫苗候选物。本研究旨在使用间接酶联免疫吸附测定法探索人对 SCPA 的免疫原性。
纳入初次就诊时患有急性咽炎体征和症状且咽喉部分离出 GAS 的儿童（n = 72）。相隔 4 周采集急性期和恢复期血清。使用重组 SCPA 肽作为抗原进行 ELISA。
恢复期抗 SCPA 的平均水平是急性期抗 SCPA 平均水平的两倍，差异具有统计学意义（P < 0.0001）。所有 2 - 12 岁儿童的恢复期抗 SCPA 均有升高。
我们的观察结果证实，SCPA 在感染 A 组链球菌性咽炎的儿童中具有高度免疫原性。需要进一步研究以表征免疫反应，包括抗体亚类。
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