背景:同时检测疟疾抗原的免疫测定平台,包括富含组氨酸的蛋白2(HRP2)/HRP3和疟原虫乳酸脱氢酶(pLDH),是用于快速诊断测试评估的有用的流行病学工具。这项研究提供了两个多重平台的比较评估,以鉴定存在或不存在HRP2/HRP3表达的恶性疟原虫,表明hrp2/hrp3缺失和其他疟原虫物种。此外,在这些平台上进行的疟疾抗原测量之间的相关性在用测定标准或国际标准进行校准后进行评估,并检查疟原虫物种之间的交叉反应性.
方法:由世界卫生组织(WHO)国际疟原虫抗原标准组成的由77名成员组成的标本小组,恶性疟原虫和诺氏疟原虫的培养寄生虫,和恶性疟原虫单一感染的临床标本,间日疟原虫,和疟原虫以全血和干血斑(DBS)标本形式产生。HRP2,恶性疟原虫特异性pLDH(PfLDH)的测定,间日疟原虫特异性pLDH(PvLDH),和所有人类疟原虫物种泛疟疾pLDH(PanLDH)在人类疟疾阵列Q-Plex和xMAP平台上进行了评估。
结果:与Q-Plex相比,xMAP对全血和DBS中hrp2缺失的恶性疟原虫和疟原虫物种的鉴定具有更高的正一致性百分比。对于全血样本,PfLDH(Pearsonr=0.9926)和PvLDH(r=0)两个平台之间呈高度正相关。9792),HRP2的中度正相关(r=0.7432),与PanLDH的相关性较差(r=0.6139)。在DBS上两个平台之间的Pearson相关性分析中,相同的测定结果分别为r=0.9828,r=0.7679,r=0.6432和r=0.8957。xMAPHRP2测定似乎与HRP3交叉反应,而Q-Plex没有。Q-PlexPfLDH测定法与疟疾疟原虫交叉反应,而xMAP没有。对于这两个平台,在PvLDH测定中检测到P.knowlesi。世卫组织国际标准允许在HRP2、PfLDH、和全血和DBS中的PvLDH测定。
结论:Q-Plex和xMAP在鉴定具有hrp2/hrp3缺失的恶性疟原虫突变体方面表现出良好的一致性,和其他疟原虫物种。两个平台的定量结果,归一化为HRP2、PfLDH、和PvLDH,显示出良好的一致性,并应允许对这两个平台产生的结果进行比较和分析。
BACKGROUND: Immunoassay platforms that simultaneously detect malaria antigens including histidine-rich protein 2 (
HRP2)/HRP3 and Plasmodium lactate dehydrogenase (pLDH), are useful epidemiological tools for rapid diagnostic test evaluation. This study presents the comparative evaluation of two multiplex platforms in identifying Plasmodium falciparum with presence or absence of
HRP2/HRP3 expression as being indicative of
hrp2/hrp3 deletions and other Plasmodium species. Moreover, correlation between the malaria antigen measurements performed at these platforms is assessed after calibrating with either assay standards or international standards and the cross-reactivity among Plasmodium species is examined.
METHODS: A 77-member panel of specimens composed of the World Health Organization (WHO) international Plasmodium antigen standards, cultured parasites for P. falciparum and Plasmodium knowlesi, and clinical specimens with mono-infections for P. falciparum, Plasmodium vivax, and Plasmodium malariae was generated as both whole blood and dried blood spot (DBS) specimens. Assays for HRP2, P. falciparum-specific pLDH (PfLDH), P. vivax-specific pLDH (PvLDH), and all human Plasmodium species Pan malaria pLDH (PanLDH) on the Human Malaria Array Q-Plex and the xMAP platforms were evaluated with these panels.
RESULTS: The xMAP showed a higher percent positive agreement for identification of hrp2-deleted P. falciparum and Plasmodium species in whole blood and DBS than the Q-Plex. For whole blood samples, there was a highly positive correlation between the two platforms for PfLDH (Pearson r = 0.9926) and PvLDH (r = 0. 9792), moderate positive correlation for HRP2 (r = 0.7432), and poor correlation for PanLDH (r = 0.6139). In Pearson correlation analysis between the two platforms on the DBS, the same assays were r = 0.9828, r = 0.7679, r = 0.6432, and r = 0.8957, respectively. The xMAP
HRP2 assay appeared to cross-react with HRP3, while the Q-Plex did not. The Q-Plex PfLDH assay cross-reacted with P. malariae, while the xMAP did not. For both platforms, P. knowlesi was detected on the PvLDH assay. The WHO international standards allowed normalization across both platforms on their
HRP2, PfLDH, and PvLDH assays in whole blood and DBS.
CONCLUSIONS: Q-Plex and xMAP show good agreement for identification of P. falciparum mutants with hrp2/hrp3 deletions, and other Plasmodium species. Quantitative results from both platforms, normalized into international units for HRP2, PfLDH, and PvLDH, showed good agreement and should allow comparison and analysis of results generated by either platform.