Rosana Yeva, Lusiana Diana Intan Gabriella, Yasmon Andi
Department of Microbiology, Faculty of Medicine, Universitas Indonesia-Cipto Mangunkusumo Hospital, Jakarta, Indonesia.
Department of Microbiology, Master's Programme in Biomedical Science, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia.
Iran J Microbiol. 2022 Aug;14(4):606-610. doi: 10.18502/ijm.v14i4.10248.
Blocking the attachment of diphtheria toxins to host cells through the intact receptor binding site ( B) was the initial mechanism of action of the diphtheria vaccine. Diphtheria outbreaks in populations with good vaccination coverage can be caused by mutations or changes in the genetic structure of the B protein. The aim of this study was to characterize the Tox B protein produced by isolated from 2018 to 2019 in patients in Jakarta who had already received the diphtheria vaccine.
Of the 89 throat swab specimens of patients with a clinical diagnosis of diphtheria, 10 were positive for diphtheria and toxin. PCR was used to amplify the B DNA fragment in the 10 positive isolates. DNA sequencing was conducted with overlapping primers and the DNA sequences were analysed by using SeqScape V2.7.
Of the 10 isolates, nine isolate showed a DNA mutation (G30A), but the mutation did not change the amino acid encoding arginin (silent mutation). Our findings indicate that the efficacy of the diphtheria vaccine used in Indonesia has not decreased because of mutations in the B genes not change the amino acid.
Overall, there are no amino acid changes in the B protein, indicating that the outbreaks are not affected by mutation in B. Another possible mechanism - overexpression of the toxin - is likely responsible for causing diphtheria in patients who have a complete history of immunization in Indonesia.
通过完整的受体结合位点（B）阻断白喉毒素与宿主细胞的附着是白喉疫苗最初的作用机制。在疫苗接种覆盖率良好的人群中发生白喉疫情，可能是由B蛋白基因结构的突变或变化引起的。本研究的目的是对2018年至2019年从雅加达已接种白喉疫苗的患者中分离出的菌株所产生的Tox B蛋白进行特征分析。
在89份临床诊断为白喉的患者咽喉拭子标本中，10份白喉和毒素检测呈阳性。采用聚合酶链反应（PCR）扩增10株阳性分离株中的B DNA片段。使用重叠引物进行DNA测序，并使用SeqScape V2.7分析DNA序列。
在10株分离株中，9株分离株显示出DNA突变（G30A），但该突变未改变编码精氨酸的氨基酸（沉默突变）。我们的研究结果表明，印度尼西亚使用的白喉疫苗的效力并未因B基因的突变而降低，因为该突变未改变氨基酸。
总体而言，B蛋白没有氨基酸变化，这表明疫情不受B基因突变的影响。另一种可能的机制——毒素的过度表达——可能是导致印度尼西亚有完整免疫史的患者患白喉的原因。
