Beniwal R K, Nichani A K, Sharma R D, Rakha N K, Suri D, Sarup S
Department of Veterinary Medicine, Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana, India.
Trop Anim Health Prod. 1997 Nov;29(4 Suppl):109S-113S. doi: 10.1007/BF02632947.
Bovine tropical theileriosis caused by Theileria annulata is an economically important disease of cattle in India. The disease has assumed paramount importance with the intensification of cross-breeding programmes aimed at enhancing milk production in the country. To control this disease, a cell culture vaccine was developed in this department by continuous passaging of T. annulata (Hisar) schizonts in vitro. Current work in this department has concentrated on the epidemiology of theileriosis: development of the cell culture vaccine for very young calves and pregnant cows; evaluation of serological responses using immunofluorescent antibody (IFA) tests and Enzyme-linked immunosorbent antibody assays (ELISA); studies on the duration of immunity stimulated by the cell culture vaccine; the immune/susceptible status of calves born to vaccinated dams. Results have shown the following. Clinical cases of theileriosis were mainly observed in young calves below two months of age followed by adults in exotic and cross-bred animals. Amongst indigenous animals, only young calves below two months of age suffered from clinical disease. Clinical cases of theileriosis mainly occurred between the months of April to October. The T. annulata schizont cell culture vaccine developed in the department was extensively used in the susceptible calves and pregnant/lactating cows in the field. Sufficiently high antibody titres were detected by both schizont as well as piroplasm antigen using both ELISA and IFAT. The results indicated that the vaccine was safe, potent and effective for all breeds and age groups of cattle under field conditions. ELISA was standardised for T. annulata using three antigens, viz.: soluble piroplasm, soluble schizont and cellular schizont antigens. Comparison of results with IFAT showed that ELISA is more sensitive, objective, reliable and specific as well as less cumbersome than IFAT. Piroplasm, cellular schizont and soluble schizont antigens were found to be suitable for the detection of antitheilerial antibodies as per their order in ELISA. Studies on the duration of immunity stimulated by the T. annulata schizont cell culture vaccine indicated that immunity started waning after six months. Calves born of dams immunised against T. annulata with the cell culture vaccine were found to be fully susceptible to theileriosis soon after birth. This indicated that there was no passive transfer of immunity from dams to their offspring through colostrum.
由环形泰勒虫引起的牛热带泰勒虫病是印度牛群中一种具有重要经济影响的疾病。随着该国旨在提高牛奶产量的杂交育种计划的强化，这种疾病变得至关重要。为了控制这种疾病，该部门通过在体外连续传代环形泰勒虫（希萨尔株）裂殖体开发了一种细胞培养疫苗。该部门目前的工作集中在泰勒虫病的流行病学研究：为非常年幼的犊牛和怀孕母牛开发细胞培养疫苗；使用免疫荧光抗体（IFA）试验和酶联免疫吸附抗体测定（ELISA）评估血清学反应；研究细胞培养疫苗刺激的免疫持续时间；接种疫苗的母牛所生犊牛的免疫/易感状态。结果如下。泰勒虫病的临床病例主要在两个月龄以下的幼龄犊牛中观察到，其次是外来品种和杂交品种的成年牛。在本地品种动物中，只有两个月龄以下的幼龄犊牛患临床疾病。泰勒虫病的临床病例主要发生在4月至10月之间。该部门开发的环形泰勒虫裂殖体细胞培养疫苗在田间易感犊牛和怀孕/泌乳母牛中广泛使用。使用ELISA和IFAT检测裂殖体以及梨形虫抗原均检测到足够高的抗体滴度。结果表明，该疫苗在田间条件下对所有品种和年龄组的牛都是安全、有效和高效的。使用三种抗原（即可溶性梨形虫、可溶性裂殖体和细胞裂殖体抗原）对环形泰勒虫的ELISA进行了标准化。与IFAT的结果比较表明，ELISA比IFAT更敏感、客观、可靠和特异，并且比IFAT更简便。在ELISA中，梨形虫、细胞裂殖体和可溶性裂殖体抗原按顺序被发现适合用于检测抗泰勒虫抗体。对环形泰勒虫裂殖体细胞培养疫苗刺激的免疫持续时间的研究表明，免疫在六个月后开始减弱。发现用细胞培养疫苗免疫环形泰勒虫的母牛所生的犊牛在出生后很快就对泰勒虫病完全易感。这表明免疫没有通过初乳从母牛被动转移到其后代。
