Bayissa Berecha, Sirak Asegedech, Worku Adane, Zewude Aboma, Zeleke Yemisrach, Chanyalew Mahlet, Gumi Balako, Berg Stefan, Conlan Andrew, Hewinson R Glyn, Wood James L N, Vordermeier H Martin, Ameni Gobena
Animal Health and Zoonotic Research Unit, Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
Vaccine Production and Drug Formulation Directorate, National Veterinary Institute, Debre Zeit, Ethiopia.
Front Vet Sci. 2021 Jul 22;8:702402. doi: 10.3389/fvets.2021.702402. eCollection 2021.
Bovine tuberculosis (bTB) is prevalent in intensive dairy farms in Ethiopia. Vaccination could be an alternative control approach given the socio-economic challenges of a test-and-slaughter control strategy. The efficacy of the BCG was evaluated on 40 Holstein-Friesian (HF) and zebu crossbred calves recruited from single intradermal cervical comparative tuberculin (SICCT) test negative herds and randomly allocated into two groups. Twenty-two calves were vaccinated within 2 weeks of age, and 18 were kept as a control. Six weeks post-vaccination, the two groups were exposed and kept mixed with known SICCT test positive cows for 1 year. Immune responses were monitored by interferon gamma (IFN-γ) release assay (IGRA), SICCT test, and antibody assay. Vaccinated calves developed strong responses to the SICCT test at the sixth week post-vaccination, but did not respond to ESAT-6/CFP-10 peptide antigen-based IGRA. During the exposure, IFN-γ response to the specific peptide cocktail [ = 26.96; < 0.001] and skin reaction to the specific proteins cocktail [ ; < 0.001] increased progressively in both groups while their antibody responses were low. The prevalence of bTB was 88.9% (95% CI: 65.3-98.6) and 63.6% (95% CI: 40.7-83.8) in the control and vaccinated calves, respectively, based on isolation, giving a direct protective efficacy estimate of 28.4% (95% CI: -2.7 to 50.1). The proportion of vaccinated calves with lesion was 7.0% (34/484) against 11.4% (45/396) in control calves, representing a 38% (95% CI: 5.8-59.4) reduction of lesion prevalence. Besides, the severity of pathology was significantly lower (Mann-Whitney -test, < 0.05) in vaccinated (median score = 2.0, IQR = 0-4.75) than in control (median score = 5, IQR = 3.0-6.25) calves. Moreover, survival from infection in vaccinated calves was significantly (log-rank test: χ = 6.749, < 0.01) higher than that of the control calves. In conclusion, the efficacy of BCG was low, but the reduced frequency and severity of lesion in vaccinated calves could suggest its potential role in containing onward transmission.
牛结核病（bTB）在埃塞俄比亚的集约化奶牛场中普遍存在。鉴于检测和扑杀控制策略面临的社会经济挑战，疫苗接种可能是一种替代控制方法。对从单剂量皮内颈侧比较结核菌素（SICCT）检测呈阴性的牛群中招募的40头荷斯坦-弗里生（HF）和瘤牛杂交犊牛进行了卡介苗（BCG）效力评估，并将其随机分为两组。22头犊牛在2周龄内接种疫苗，18头作为对照。接种疫苗6周后，将两组犊牛与已知SICCT检测呈阳性的奶牛接触并混养1年。通过干扰素γ（IFN-γ）释放试验（IGRA）、SICCT检测和抗体检测来监测免疫反应。接种疫苗的犊牛在接种后第6周对SICCT检测产生了强烈反应，但对基于ESAT-6/CFP-10肽抗原的IGRA没有反应。在接触期间，两组对特定肽混合物的IFN-γ反应[ = 26.96； < 0.001]和对特定蛋白质混合物的皮肤反应[ ； < 0.001]均逐渐增加，而它们的抗体反应较低。基于 分离，对照犊牛和接种疫苗的犊牛中bTB的患病率分别为88.9%（95%置信区间：65.3 - 98.6）和63.6%（95%置信区间：40.7 - 83.8），直接保护效力估计为28.4%（95%置信区间： - 2.7至50.1）。接种疫苗的犊牛中出现病变的比例为7.0%（34/484），而对照犊牛为11.4%（45/396），病变患病率降低了38%（95%置信区间：5.8 - 59.4）。此外，接种疫苗的犊牛（中位数评分 = 2.0，四分位距 = 0 - 4.75）的病理学严重程度明显低于对照犊牛（中位数评分 = 5，四分位距 = 3.0 - 6.25）（Mann-Whitney -检验， < 0.05）。此外，接种疫苗的犊牛从 感染中的存活率显著高于对照犊牛（对数秩检验：χ = 6.749， < 0.01）。总之，卡介苗的效力较低，但接种疫苗的犊牛病变频率和严重程度的降低可能表明其在控制疾病传播方面的潜在作用。 （注：原文中部分表述不完整，翻译时尽量忠实原文，可能存在一定理解困难。）
