Clinical Relevance of CagA-specific Antibodies Related to CagA Status of Heliobacter pylori Isolates Using Immunofluorescence Test and PCR
Clinical Relevance of CagA-specific Antibodies Related to CagA Status of Heliobacter pylori Isolates Using Immunofluorescence Test and PCR
复制标题
使用免疫荧光测试和 PCR 检测与幽门螺杆菌 CagA 状态相关的 CagA 特异性抗体的临床相关性
作者：
R. Krausse;L. Garten;T. Harder;U. Ullmann;T. Birkner;M. Doniec;H. Grimm
摘要背景：cagA（细胞毒素相关基因A）蛋白存在于约50%的幽门螺杆菌菌株中;其与胃十二指肠疾病的临床相关性尚不确定。
患者和方法：用免疫印迹法检测189例经内镜和组织学证实的胃十二指肠疾病患者血清中cagA IgG抗体的频率。此外，38 H.采用免疫荧光试验（IFT）和PCR方法分别检测pylori cagA蛋白和cagA基因序列。
结果如下：在胃肠道疾病（慢性胃炎、胃溃疡、十二指肠溃疡和慢性胃炎）和正常胃粘膜患者中，抗cagA IgG抗体阳性率分别为54.3%~ 60.0%和28.6%。不同临床实体之间的抗cagA IgG血清阳性率无显著差异。CagA阳性（cagA+）H. PCR和IFT检测pylori菌株的阳性率分别为44.7%和50%。23例cagA+菌株感染者中有22例有抗cagA抗体。以PCR为金标准，cagA IgG Western blot的敏感性和特异性分别为100.0%和35.0%，cagA IFT的敏感性和特异性分别为76.5%和71.4%。cagA+H.慢性胃炎、胃溃疡和十二指肠溃疡患者PCR和IFT检出pylori菌株的阳性率分别为66.7%、80%和30.4%（P < 0.05和P < 0.01）。
结论：本研究中，H. IgG蛋白质印迹法诊断的幽门螺杆菌感染对疾病的严重程度没有预测价值。相反，H.通过IFT或PCR诊断的幽门螺杆菌分离株是严重疾病的预测标志物，因此，在评估感染菌株的毒力方面也具有临床相关性。
AbstractBackground: The cagA (cytotoxin-associated gene A) protein is found in about 50% of Helicobacter pylori strains; its clinical relevance in gastroduodenal disease is uncertain.
Patients and Methods: The frequency of IgG antibodies to cagA was studied by using a commercial Western blot assay in sera of 189 patients with endoscopically and histologically confirmed gastroduodenal disease. In addition, 38 H. pylori strains isolated from biopsies were analyzed by immunofluorescence test (IFT) and PCR for detection of cagA protein and cagA gene sequences, respectively.
Results: 54.3–60.0% of all patients with gastrointestinal diseases (chronic gastritis, gastric or duodenal ulcer and chronic duodenitis) and 28.6% with a normal mucosa were found to be positive for anti-cagA IgG antibodies. There was no significant difference in anti-cagA IgG seroprevalence between the different clinical entities. CagA-positive (cagA+) H. pylori strains were detected in 44.7% and 50% of the 38 isolates by PCR and IFT, respectively. 22 of 23 patients infected with cagA+ strains had anti-cagA antibodies. Using PCR as a gold standard, the sensitivity and specificity of the cagA IgG Western blot were 100.0% and 35.0%, respectively; the sensitivity and specificity of the cagA IFT were 76.5% and 71.4%, respectively. The incidence of the cagA+H. pylori strains detected either by PCR or IFT was significantly higher (p < 0.05 and p < 0.01, respectively) in patients with chronic duodenitis, gastric or duodenal ulcer compared to patients with chronic gastritis (66.7%, 80% and 30.4%, respectively).
Conclusion: In this study the cagA-specific serological status in H. pylori infections as diagnosed by IgG Western blot was of no predictive value for severity of disease. In contrast, the cagA status of H. pylori isolates, diagnosed by IFT or PCR, was a predictive marker for severe disease and, therefore, also of clinical relevance in the assessment of the virulence of the infecting strain.