Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic.
Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic.
PLoS Negl Trop Dis. 2019 Nov 21;13(11):e0007832. doi: 10.1371/journal.pntd.0007832. eCollection 2019 Nov.
Canine leishmaniasis (CanL) is a severe chronic disease caused by Leishmania infantum and transmitted by sand flies of which the main vector in the Western part of the Mediterranean basin is Phlebotomus perniciosus. Previously, an immunochromatographic test (ICT) was proposed to allow rapid evaluation of dog exposure to P. perniciosus. In the present study, we optimized the prototype and evaluated the detection accuracy of the ICT in field conditions. Possible cross-reactions with other hematophagous arthropods were also assessed.
METHODOLOGY/PRINCIPAL FINDINGS: The ICT was optimized by expressing the rSP03B protein in a HEK293 cell line, which delivered an increased specificity (94.92%). The ICT showed an excellent reproducibility and inter-person reliability, and was optimized for use with whole canine blood which rendered an excellent degree of agreement with the use of serum. Field detectability of the ICT was assessed by screening 186 dogs from different CanL endemic areas with both the SGH-ELISA and the ICT, and 154 longitudinally sampled dogs only with the ICT. The ICT results corresponded to the SGH-ELISA for most areas, depending on the statistical measure used. Furthermore, the ICT was able to show a clear seasonal fluctuation in the proportion of bitten dogs. Finally, we excluded cross-reactions between non-vector species and confirmed favorable cross-reactions with other L. infantum vectors belonging to the subgenus Larroussius.
CONCLUSIONS/SIGNIFICANCE: We have successfully optimized the ICT, now also suitable to be used with whole canine blood. The test is able to reflect the seasonal fluctuation in dog exposure and showed a good detectability in a field population of naturally exposed dogs, particularly in areas with a high seroprevalence of bitten dogs. Furthermore, our study showed the existence of favorable cross-reactions with other sand fly vectors thereby expanding its use in the field.
犬利什曼病（CanL）是一种由利什曼原虫引起的严重慢性疾病，通过沙蝇传播，其中在西地中海盆地的主要媒介是白蛉属。此前，提出了一种免疫层析试验（ICT）来快速评估狗接触白蛉属的情况。在本研究中，我们对原型进行了优化，并评估了 ICT 在现场条件下的检测准确性。还评估了与其他吸血节肢动物的可能交叉反应。
方法/主要发现：通过在 HEK293 细胞系中表达 rSP03B 蛋白对 ICT 进行了优化，这提高了特异性（94.92%）。ICT 显示出极好的重现性和人与人之间的可靠性，并针对全犬血进行了优化，与使用血清相比具有极好的一致性。通过对来自不同利什曼病流行地区的 186 只狗同时使用 SGH-ELISA 和 ICT 以及仅对 154 只纵向采样狗使用 ICT 进行筛选，评估了 ICT 的现场检测能力。根据使用的统计措施，ICT 结果与 SGH-ELISA 对应大多数地区。此外，ICT 能够清楚地显示出被叮咬狗的比例的季节性波动。最后，我们排除了非媒介物种之间的交叉反应，并证实了与属于 Larroussius 亚属的其他利什曼原虫媒介的有利交叉反应。
结论/意义：我们已经成功地优化了 ICT，现在也可以与全犬血一起使用。该测试能够反映狗接触的季节性波动，并在自然暴露的犬类现场种群中表现出良好的检测能力，尤其是在被叮咬狗的血清阳性率较高的地区。此外，我们的研究表明与其他沙蝇媒介存在有利的交叉反应，从而扩大了其在野外的应用。
