Background

Bovine tropical theileriosis (BTT) is a haemoprotozoan tick-borne disease that implicates huge losses to livestock in terms of considerable mortality and morbidity in tropical and subtropical regions of the globe. Currently available diagnostic methods have less specificity and sensitivity towards the detection of Theileria species. Therefore, an attempt was made to diagnose Theileria annulata by targeting a multi-copy gene, viz. mitochondrially encoded cytochrome b (MT-CYB) gene via polymerase chain reaction (PCR) in different agro-zones of India.

Methods and Results

129 cattle blood samples were collected from major livestock rearing regions of India and processed for both molecular and microscopic techniques. Screening of Giemsa-stained thin blood smears was able to detect 14 samples (10.85%) as positive for T. annulata. However, the MT-CYB gene-based PCR assay detected 107 samples (82.94%) positive for T. annulata out of 129 samples. Furthermore, the MT-CYB gene-based PCR assay was standardized in terms of its sensitivity and specificity. Specificity of PCR assay was evaluated against other common haemoprotozoan parasites of tropical countries viz. Babesia bigemina, Anaplasma marginale and Trypanosoma evansi. The multi-copy MT-CYB gene-based PCR assay provided an optimum level of sensitivity (up to the level of 10 femtogram) and high specificity. Haematological examination (Hb, PCV and TLC) of 113 samples revealed significantly (p < 0.05) decreased Hb and PCV levels in positive animals in comparison with the control group of healthy animals. However, the control group had significantly higher (p < 0.001) TLC levels than the positive group.

Conclusion

The MT-CYB gene-based PCR assay was found to be highly sensitive that can accurately detect the occurrence of T. annulata infection in carrier animals which are potential infection sources to healthier populations in naive demographic locations through infected ticks.

中文翻译：

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基于多拷贝核酸的牛热带泰勒虫病诊断试验

背景

牛热带泰勒虫病 (BTT) 是一种由血原虫蜱传播的疾病，在全球热带和亚热带地区的死亡率和发病率相当高，对牲畜造成巨大损失。目前可用的诊断方法对检测泰勒虫物种的特异性和敏感性较低。因此，尝试通过靶向多拷贝基因（即。印度不同农区通过聚合酶链反应 (PCR) 线粒体编码细胞色素 b (MT-CYB) 基因。

方法和结果

从印度的主要牲畜饲养区采集了 129 份牛血样，并针对分子和显微技术进行了处理。吉姆萨染色薄血涂片的筛选能够检测出 14 个样本 (10.85%) 为T. annulata 阳性。然而，基于 MT-CYB 基因的 PCR 检测在 129 个样本中检测到 107 个样本 (82.94%) 对T. annulata呈阳性。此外，基于 MT-CYB 基因的 PCR 测定在其敏感性和特异性方面是标准化的。PCR 检测的特异性针对热带国家的其他常见血原虫寄生虫进行了评估，即。大叶巴贝虫、边缘无形体和伊氏锥虫. 基于多拷贝 MT-CYB 基因的 PCR 测定提供了最佳水平的灵敏度（高达 10 飞克水平）和高特异性。113 份样本的血液学检查（Hb、PCV 和 TLC）显示 ，与健康动物的对照组相比，阳性动物的 Hb 和 PCV 水平显着降低（ p < 0.05）。然而，对照组的 TLC水平显着高于阳性组（ p <0.001）。

结论

发现基于 MT-CYB 基因的 PCR 测定具有高度敏感性，可以准确地检测携带动物中环虫感染的发生，这些携带动物是通过受感染的蜱对幼稚人口统计学地点的健康人群的潜在感染源。