Three different genotypes of chikungunya virus (CHIKV) have been classified: East/Central/South African (ECSA), West African (WA), and Asian. Previously, a rapid immunochromatographic (IC) test detecting CHIKV E1-antigen showed high sensitivity for certain ECSA-genotype viruses, but this test showed poor performance against the Asian-genotype virus that is spreading in the American continents. We found that the reactivity of one monoclonal antibody (MAb) used in the IC rapid diagnostic test (RDT) is affected by a single amino acid substitution in E1. Therefore, we developed new MAbs that exhibited specific recognition of all three genotypes of CHIKV. Using a combination of the newly generated MAbs, we developed a novel version of the IC RDT with improved sensitivity to Asian-genotype CHIKV. To evaluate the sensitivity, specificity, and cross-reactivity of the new version of the IC RDT, we first used CHIKV isolates and E1-pseudotyped lentiviral vectors. We then used clinical specimens obtained in Aruba in 2015 and in Bangladesh in 2017 for further evaluation of RDT sensitivity and specificity. Another alphavirus, sindbis virus (SINV), was used to test RDT cross-reactivity. The new version of the RDT detected Asian-genotype CHIKV at titers as low as 10^4 plaque-forming units per mL, a concentration that was below the limit of detection of the old version. The new RDT had sensitivity to the ECSA genotype that was comparable with that of the old version, yielding 92% (92 out of 100) sensitivity (95% confidence interval 85.0–95.9) and 100% (100 out of 100) specificity against a panel of 100 CHIKV-positive and 100 CHIKV-negative patient sera obtained in the 2017 outbreak in Bangladesh. Our newly developed CHIKV antigen-detecting RDT demonstrated high levels of sensitivity and lacked cross-reactivity against SINV. These results suggested that our new version of the CHIKV E1-antigen RDT is promising for use in areas in which the Asian and ECSA genotypes of CHIKV circulate. Further validation with large numbers of CHIKV-positive and -negative clinical samples is warranted. (323 words).

中文翻译：

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跨基因型针对基孔肯雅病毒E1抗原的单克隆抗体在免疫色谱快速诊断测试中的应用前景广阔。

基孔肯雅病毒（CHIKV）的三种不同基因型已被分类：东/中/南非（ECSA），西非（WA）和亚洲。以前，检测CHIKV E1抗原的快速免疫色谱（IC）测试显示出对某些ECSA基因型病毒的高敏感性，但该测试显示了对在美洲大陆传播的亚洲基因型病毒的不良性能。我们发现，IC快速诊断测试（RDT）中使用的一种单克隆抗体（MAb）的反应性受E1中的单个氨基酸取代影响。因此，我们开发了新的单克隆抗体，这些抗体显示出对CHIKV的所有三种基因型的特异性识别。通过结合使用新生成的单克隆抗体，我们开发了新型IC RDT，对亚洲基因型CHIKV的敏感性更高。为了评估敏感性，特异性，和新版IC RDT的交叉反应性，我们首先使用CHIKV分离株和E1假型慢病毒载体。然后，我们使用2015年在阿鲁巴和2017年在孟加拉国获得的临床标本进一步评估RDT的敏感性和特异性。另一种alpha病毒即sindbis病毒（SINV）用于测试RDT的交叉反应性。新版本的RDT检测到的亚洲基因型CHIKV滴度低至每毫升10 ^ 4个噬菌斑形成单位，其浓度低于旧版本的检测极限。新的RDT对ECSA基因型的敏感性与旧版本相当，产生92％（100分之92）的敏感性（95％置信区间85.0-95）。在2017年孟加拉国暴发中获得的一组100例CHIKV阳性和100例CHIKV阴性的患者血清具有9）和100％（100分之100）的特异性。我们新开发的CHIKV抗原检测RDT显示出高水平的敏感性，并且缺乏针对SINV的交叉反应性。这些结果表明，我们的新版CHIKV E1抗原RDT有望用于CHIKV亚洲和ECSA基因型传播的地区。有必要对大量CHIKV阳性和阴性临床样品进行进一步验证。（323个字）。有必要对大量CHIKV阳性和阴性临床样品进行进一步验证。（323个字）。有必要对大量CHIKV阳性和阴性临床样品进行进一步验证。（323个字）。