Jacobson R H, Chang Y F, Shin S J
Diagnostic Laboratory, College of Veterinary Medicine, Cornell University, Ithaca, NY 14852-5786, USA.
Semin Vet Med Surg Small Anim. 1996 Aug;11(3):172-82. doi: 10.1016/s1096-2867(96)80030-2.
Serological assays for detection of canine antibodies to the Lyme agent generally have been difficult to validate because an acceptable standard of comparison such as unequivocal proof of infection status has not been available. For practical and logistical reasons, it has not been possible to use culture of organism from infected animals, seroconversion in a large number of field dogs, or clinical criteria as the standard of comparison for validation of assays. Therefore, estimates of diagnostic sensitivity and specificity based on an appropriate gold standard have not been available. When it was discovered how to infect laboratory dogs via ticks infected with Borrelia burgdorferi, it was possible to define the kinetics and magnitude of the antibody response that might be expected in nature. ELISA and Western immunoblot data from experimental dogs were then compared and correlated with results of the same tests on dogs from endemic and nonendomic areas. Coupled with studies on cross-reactive antibodies elicited from other infectious agents or autoimmune phenomena, it was possible to account for interfering antibodies and to establish estimates of diagnostic sensitivity and specificity for the ELISA based on objective criteria. Such validated assays can predict, with a relatively high degree of proficiency, the infection and/or vaccinal status of animals. These assays have shown that some dogs, vaccinated with the commercially available whole-cell Lyme bacterins develop typical signs of Lyme disease but have no evidence of an underlying infection; antibody elicited only by the vaccine and not by infection is detectable in these animals. Western immunoblot can also confirm infection in animals of equivocal ELISA status if their bands have been evaluated for specificity of antibodies to B burgdorferi. Serology can be a very useful aid in the diagnosis of Lyme disease, but it requires that the assays used have been subjected to rigorous validation criteria. When that is not performed, an unacceptable level of false-positive and false-negative test results is virtually assured.
用于检测犬类抗莱姆病病原体抗体的血清学检测方法通常难以验证，因为缺乏可接受的比较标准，如明确的感染状态证据。出于实际和后勤方面的原因，无法使用从感染动物分离的病原体培养物、大量野外犬的血清转化情况或临床标准作为检测方法验证的比较标准。因此，基于适当金标准的诊断敏感性和特异性估计值无法获得。当发现如何通过感染伯氏疏螺旋体的蜱虫感染实验犬时，就有可能确定在自然情况下可能预期的抗体反应动力学和强度。然后将实验犬的ELISA和Western免疫印迹数据与来自流行区和非流行区犬的相同检测结果进行比较和关联。结合对其他传染病原体或自身免疫现象引发的交叉反应抗体的研究，就有可能解释干扰抗体，并基于客观标准建立ELISA诊断敏感性和特异性的估计值。这种经过验证的检测方法能够以较高的准确性预测动物的感染和/或疫苗接种状态。这些检测方法表明，一些接种市售全细胞莱姆病疫苗的犬出现了莱姆病的典型症状，但没有潜在感染的证据；在这些动物中可检测到仅由疫苗而非感染引发的抗体。如果对Western免疫印迹条带针对伯氏疏螺旋体抗体的特异性进行评估，也可以确认ELISA结果不明确的动物是否感染。血清学在莱姆病诊断中可能是非常有用的辅助手段，但它要求所使用的检测方法经过严格的验证标准。如果不这样做，几乎肯定会出现不可接受的假阳性和假阴性检测结果水平。
