Oleaga-Pérez A, Pérez-Sánchez R, Astigarraga A, Encinas-Grandes A
Laboratory of Parasitology, IRNA, CSIC, Salamanca, Spain.
Vet Parasitol. 1994 Mar;52(1-2):97-111. doi: 10.1016/0304-4017(94)90040-x.
Ornithodoros erraticus is the European vector of African Swine Fever. It is therefore essential to know on which pig farms the tick is present in order to prevent contact with swine. Currently, studies are being made to ascertain this through the detection of anti-O. erraticus antibodies in the sera of swine, using three extracts from the salivary glands of the parasite (SGE): a complete extract (SGE-1), a soluble antigens extract (SGE-2), and a tissue antigens extract (SGE-3). The results of the present work show that SGE-2 gives the best differentiation between swine bitten by O. erraticus and unbitten swine in the enzyme-linked immunosorbent assay (ELISA). Using this extract, an optical density (OD) five-fold higher than the basal OD indicates that the pigs carry anti-O. erraticus antibodies. A serological study carried out in Salamanca with 8083 sera from 1756 pig farms revealed the presence of the parasite on 135 farms. However, during this study we noticed that some sera of unbitten animals gave false-positive reactions. Western blot analysis of SGE-2 of these false-positive sera demonstrated the same bands (except for two) as the real anti-O. erraticus sera. We observed, in ELISA and Western blot analysis, that such false-positive sera only recognised carbohydrate epitopes on SGE-2. This reactivity disappeared on deglycosylated SGE-2 (SGE-2-P). Therefore, SGE-2-P is the antigen that confers the greatest specificity to serology. In this study it was also observed that the low levels of anti-O. erraticus antibodies found in some cases may be because the swine were bitten some months previously on a different farm or that the current farm harboured only a few specimens of O. erraticus, so pig-tick contact is unlikely and hence the pigs either only develop a primary response or the time between contacts is very long and the levels of antibodies fall. Since pigs could be bitten on a different farm, the presence of low levels of anti-O. erraticus antibodies in pig sera do not necessarily indicate the presence of the tick on the farm where sampling was carried out.
缘饰钝缘蜱是非洲猪瘟在欧洲的传播媒介。因此，了解哪些养猪场存在这种蜱虫对于防止猪只与之接触至关重要。目前，正在开展研究，通过检测猪血清中抗缘饰钝缘蜱抗体来确定这一点，使用该寄生虫唾液腺的三种提取物（唾液腺提取物，SGE）：完整提取物（SGE - 1）、可溶性抗原提取物（SGE - 2）和组织抗原提取物（SGE - 3）。本研究结果表明，在酶联免疫吸附测定（ELISA）中，SGE - 2在区分被缘饰钝缘蜱叮咬的猪和未被叮咬的猪方面表现最佳。使用这种提取物时，光密度（OD）比基础OD高五倍表明猪携带抗缘饰钝缘蜱抗体。在萨拉曼卡对来自1756个养猪场的8083份血清进行的血清学研究显示，有135个农场存在这种寄生虫。然而，在这项研究中我们注意到，一些未被叮咬动物的血清出现了假阳性反应。对这些假阳性血清的SGE - 2进行的蛋白质印迹分析显示，与真正的抗缘饰钝缘蜱血清具有相同的条带（除了两条）。我们在ELISA和蛋白质印迹分析中观察到，此类假阳性血清仅识别SGE - 2上的碳水化合物表位。这种反应性在去糖基化的SGE - 2（SGE - 2 - P）上消失。因此，SGE - 2 - P是赋予血清学最大特异性的抗原。在本研究中还观察到，某些情况下发现的抗缘饰钝缘蜱抗体水平较低，可能是因为猪几个月前在不同农场被叮咬过，或者当前农场仅藏有少量缘饰钝缘蜱标本，所以猪与蜱的接触不太可能发生，因此猪要么只产生初次反应，要么接触间隔时间很长且抗体水平下降。由于猪可能在不同农场被叮咬，猪血清中抗缘饰钝缘蜱抗体水平较低并不一定表明在采样农场存在这种蜱虫。
