Rebeski D E, Winger E M, Aigner H, Wright P, Crowther J, Dwinger R H
FAO/IAEA Agriculture and Biotechnology Laboratory, Seibersdorf, Austria.
Vet Parasitol. 1998 Oct;79(2):109-22. doi: 10.1016/s0304-4017(98)00162-9.
Samples of bovine serum from uninfected and African trypanosomes-infected animals were tested before and after gamma-irradiation, using three sandwich enzyme-linked immunosorbent assays (ELISA). Each test system utilized a different monoclonal antibody, reputedly allowing the specific detection of conserved-invariant cytoplasmic antigens of trypanonosomes, T. congolense, T. vivax, and T. brucei, respectively. Results have identified two groups of samples. The first contained samples where there were unequivocal ELISA results indicating positivity and negativity, for non-irradiated samples. In this group, irradiation had no effect on the diagnostic sensitivity of the assays. All samples shown to be positive before irradiation remained positive and those shown to be negative, remained negative. There was, however, a statistically significant reduction in signal in each of the ELISAs following irradiation. The second group contained samples identified before irradiation as flanking the diagnostic negative/positive threshold of OD > or =0.05. These showed a negative bias after irradiation of the order of OD -0.01, which was shown to be statistically significant by paired t-statistics. Without correction of the given diagnostic negative/positive threshold, bovine sera with OD values around the threshold were expected to deliver more false negative test results upon irradiation. This was confirmed when serological data were compared with parasitological findings; where three times more false negative test results were found from irradiated serum samples. Consequently, for this group of irradiated bovine samples tested by ELISA, the re-adjustment of the diagnostic negative/positive threshold of the ELISAs using defined irradiated serum samples is recommended; otherwise, the frequency of false negative results might be increased.
使用三种夹心酶联免疫吸附测定（ELISA），对未感染和感染非洲锥虫动物的牛血清样本在γ射线辐照前后进行了检测。每个检测系统使用一种不同的单克隆抗体，据称分别能够特异性检测刚果锥虫、活泼锥虫和布氏锥虫锥虫保守不变的细胞质抗原。结果确定了两组样本。第一组包含未辐照样本，ELISA结果明确显示阳性和阴性。在这一组中，辐照对检测的诊断敏感性没有影响。所有辐照前显示为阳性的样本仍为阳性，显示为阴性的样本仍为阴性。然而，辐照后每种ELISA中的信号均有统计学显著降低。第二组包含辐照前确定为位于诊断阴性/阳性阈值OD≥0.05两侧的样本。这些样本辐照后显示出约OD -0.01的负偏差，配对t检验显示该偏差具有统计学显著性。如果不校正给定的诊断阴性/阳性阈值，预计OD值在阈值附近的牛血清在辐照后会产生更多假阴性检测结果。将血清学数据与寄生虫学结果进行比较时证实了这一点；辐照血清样本的假阴性检测结果多出三倍。因此，对于通过ELISA检测的这组辐照牛样本，建议使用确定的辐照血清样本重新调整ELISA的诊断阴性/阳性阈值；否则，可能会增加假阴性结果的频率。
