Liu Jiayou, Drexel Jan, Andrews Blaine, Eberts Matt, Breitschwerdt Ed, Chandrashekar Ramaswamy
Assay R&D, IDEXX Laboratories Inc, Westbrook, ME, USA.
Town and Country Veterinary Clinic, Green Forest, AR, USA.
Top Companion Anim Med. 2018 Dec;33(4):114-118. doi: 10.1053/j.tcam.2018.09.003. Epub 2018 Sep 13.
Vector-borne agents comprise medically important infections affecting dogs throughout much of the world. Sensitive detection of antibodies directed at tick-borne disease-causing organisms in dogs is diagnostically important for veterinarians, pets and their owners, and epidemiologically important for public health surveillance. The SNAP 4Dx Plus Test (IDEXX Laboratories, Inc., Westbrook, ME) identifies antibodies to or infection with multiple tick-borne pathogens and canine heartworm antigen in a single assay. Recently, VetScan FLEX4 Rapid Test (Abaxis, Inc., Union City, CA) was launched as a new assay to detect tick-borne pathogen antibodies and heartworm antigen. In the present study, we evaluated the comparative performance of SNAP 4Dx Plus (SNAP) and FLEX4 Rapid Test (FLEX4) using samples selected based on geographic distributions for canine vector borne diseases, including Borrelia burgdorferi (n = 105), Anaplasma phagocytophilum (160), Anaplasma platys (115), Ehrlichia canis (154), Ehrlichia ewingii (163), Ehrlichia chaffeensis (151) and Dirofilaria immitis (105). Canine vector borne diseases infection status was established for each sample by a combination of reference methods that included necropsy (D. immitis, heartworm disease), Western immunoblotting (B. burgdorferi), immunofluorescence assays (A. phagocytophilum and E. canis) and species-specific ELISAs (A. platys, E. canis, E. ewingii and E. chaffeensis). For comparisons among the 2 assays, samples were evaluated per the manufacturers' instructions for each test kit. By testing each same sample set compared to the defined reference results, sensitivities differed substantially between SNAP and FLEX4, at 95.5 vs. 40.9%, respectively for B. burgdorferi, 97.1% vs. 61.4% for E. canis, 98.2% vs. 59.3% for E. ewingii, 64.3% vs. 35.7% for E. chaffeensis, 84.5% vs. 12.7% for A. phagocytophilum, 83.3% vs. 33.3% for A. platys, and 94.1% vs. 88.2% for D. immitis. Specificities for both rapid assay tests ranged from 98% to 100%. Based upon the comparative results derived from this study, the SNAP test was more sensitive than the FLEX4 test for detection of antibodies to all tick-borne pathogens and heartworm disease (Dirofilaria immitis) antigen in dogs.
媒介传播病原体包括在世界大部分地区影响犬类的具有重要医学意义的感染源。对犬类中针对蜱传致病生物的抗体进行灵敏检测，对兽医、宠物及其主人具有诊断重要性，对公共卫生监测具有流行病学重要性。SNAP 4Dx Plus检测（IDEXX实验室公司，缅因州韦斯特布鲁克）可在一次检测中鉴定针对多种蜱传病原体的抗体或感染以及犬心丝虫抗原。最近，VetScan FLEX4快速检测（Abaxis公司，加利福尼亚州联合市）作为一种检测蜱传病原体抗体和心丝虫抗原的新检测方法被推出。在本研究中，我们使用根据犬类媒介传播疾病的地理分布选择的样本，评估了SNAP 4Dx Plus（SNAP）和FLEX4快速检测（FLEX4）的比较性能，这些样本包括伯氏疏螺旋体（n = 105）、嗜吞噬细胞无形体（160）、血小板无形体（115）、犬埃立克体（154）、尤因埃立克体（163）、查菲埃立克体（151）和犬恶丝虫（105）。通过包括尸检（犬恶丝虫，心丝虫病）、免疫印迹法（伯氏疏螺旋体）、免疫荧光测定法（嗜吞噬细胞无形体和犬埃立克体）和种特异性酶联免疫吸附测定法（血小板无形体、犬埃立克体）（尤因埃立克体和查菲埃立克体）在内的参考方法组合，确定每个样本的犬类媒介传播疾病感染状态。为了在这两种检测方法之间进行比较，根据每个检测试剂盒的制造商说明对样本进行评估。通过将每个相同的样本集与定义的参考结果进行比较测试，SNAP和FLEX4之间的灵敏度差异很大，伯氏疏螺旋体分别为95.5%对40.9%，犬埃立克体为97.1%对61.4%，尤因埃立克体为98.2%对59.3%，查菲埃立克体为64.3%对35.7%，嗜吞噬细胞无形体为84.5%对12.7%，血小板无形体为83.3%对33.3%，犬恶丝虫为94.1%对88.2%。两种快速检测方法的特异性范围为98%至100%。根据本研究得出的比较结果，SNAP检测在检测犬类中所有蜱传病原体的抗体和心丝虫病（犬恶丝虫）抗原方面比FLEX4检测更灵敏。
