Patarroyo J H, Prates A A, Tavares C A, Mafra C L, Vargas M I
Laboratorio de Biologia e Controle de Hematozoários-BIOAGRO, Departamento de Veterinária, Universidade Federal de Viçosa, MG, Brazil.
Vet Parasitol. 1995 Oct;59(3-4):189-99. doi: 10.1016/0304-4017(94)00756-3.
Bovine babesiosis caused by Babesia bovis remains a significant constraint to beef and milk cattle production throughout the world. Exoantigens released by the parasites in culture supernatants are a potential source of antigen to induce protective immunity. An attenuated strain of B. bovis from Brazil, catalogued as BbUFV1, was maintained in vitro by the MASP method, and exoantigen-containing supernatant fluids were collected daily to form a pool representing a 72-h culture cycle for preparation of the vaccine. Exoantigen concentration was estimated using a two-site EIA. Three groups of susceptible non-splenectomised male Bos taurus cattle, 14 months old, were used. Group A (vaccinated) received two subcutaneous immunizations with a 21-day interval of B. bovis supernatant, content 6500 EIA units of exoantigens plus 1.5 mg saponin, and Group B (adjuvant control) received two injections of adjuvant alone. Four weeks after the second immunization, Groups A, B and C (control) were challenged intravenously with 10(8) virulent parasites of a heterologous B. bovis strain. The results showed that exoantigens present in in vitro cultures can induce a high degree of protection against virulent heterologous challenge exposure. In Group A only one animal showed discrete parasitaemia; all developed a fever and slight decreases in PCV, with a rapid return to normal values. One animal of Group B died; the survivors showed fever, anaemia and parasitaemia. All animals of Group C died between 7 and 13 days after challenge. Vaccination elicited both humoral and cell-mediated immune responses. In Group A, after the challenge, the maximum antibody titer was 12,800. When vaccinated, cattle were tested at the moment of challenge for B. bovis-specific cell-mediated immunity by the monocytemigration inhibition test. A mean inhibition index of 60 +/- 0.33 was observed. Preliminary Western blot analysis of the immunogen revealed at least four proteins of molecular weight ranging between 30 and 160 kDa.
由牛巴贝斯虫引起的牛巴贝斯虫病仍然是全球肉牛和奶牛生产的一个重大制约因素。寄生虫在培养上清液中释放的外抗原是诱导保护性免疫的潜在抗原来源。来自巴西的一株减毒牛巴贝斯虫菌株，编号为BbUFV1，通过MASP方法在体外保存，每天收集含外抗原的上清液以形成代表72小时培养周期的混合液，用于制备疫苗。使用双位点酶免疫测定法估计外抗原浓度。使用三组14月龄易感的未切除脾脏的雄性黄牛。A组（接种疫苗组）接受两次皮下免疫，间隔21天，接种牛巴贝斯虫上清液，含6500酶免疫测定单位的外抗原加1.5毫克皂苷，B组（佐剂对照组）仅接受两次佐剂注射。第二次免疫后四周，A、B和C组（对照组）静脉注射10⁸ 个异源牛巴贝斯虫菌株的强毒寄生虫。结果表明，体外培养物中存在的外抗原可诱导对强毒异源攻击暴露的高度保护。A组只有一只动物出现离散性寄生虫血症；所有动物都发烧，红细胞压积略有下降，并迅速恢复到正常值。B组有一只动物死亡；存活动物出现发烧、贫血和寄生虫血症。C组所有动物在攻击后7至13天内死亡。接种疫苗引发了体液免疫和细胞介导的免疫反应。在A组中，攻击后最大抗体滴度为12800。接种疫苗后，在攻击时通过单核细胞迁移抑制试验检测牛对牛巴贝斯虫特异性细胞介导的免疫。观察到平均抑制指数为60±0.33。对免疫原的初步蛋白质印迹分析显示至少有四种分子量在30至160 kDa之间的蛋白质。
