Gormley Eamonn, Ní Bhuachalla Deirdre, O'Keeffe James, Murphy Denise, Aldwell Frank E, Fitzsimons Tara, Stanley Paul, Tratalos Jamie A, McGrath Guy, Fogarty Naomi, Kenny Kevin, More Simon J, Messam Locksley L McV, Corner Leigh A L
School of Veterinary Medicine, University College Dublin (UCD), Dublin, Ireland.
Dept of Agriculture, Food and the Marine, Head of Wildlife Unit, Agriculture House, Dublin, Ireland.
PLoS One. 2017 Jan 25;12(1):e0168851. doi: 10.1371/journal.pone.0168851. eCollection 2017.
A field trial was conducted to investigate the impact of oral vaccination of free-living badgers against natural-transmitted Mycobacterium bovis infection. For a period of three years badgers were captured over seven sweeps in three zones and assigned for oral vaccination with a lipid-encapsulated BCG vaccine (Liporale-BCG) or with placebo. Badgers enrolled in Zone A were administered placebo while all badgers enrolled in Zone C were vaccinated with BCG. Badgers enrolled in the middle area, Zone B, were randomly assigned 50:50 for treatment with vaccine or placebo. Treatment in each zone remained blinded until the end of the study period. The outcome of interest was incident cases of tuberculosis measured as time to seroconversion events using the BrockTB Stat-Pak lateral flow serology test, supplemented with post-mortem examination. Among the vaccinated badgers that seroconverted, the median time to seroconversion (413 days) was significantly longer (p = 0.04) when compared with non-vaccinated animals (230 days). Survival analysis (modelling time to seroconversion) revealed that there was a significant difference in the rate of seroconversion between vaccinated and non-vaccinated badgers in Zones A and C throughout the trial period (p = 0.015). For badgers enrolled during sweeps 1-2 the Vaccine Efficacy (VE) determined from hazard rate ratios was 36% (95% CI: -62%- 75%). For badgers enrolled in these zones during sweeps 3-6, the VE was 84% (95% CI: 29%- 97%). This indicated that VE increased with the level of vaccine coverage. Post-mortem examination of badgers at the end of the trial also revealed a significant difference in the proportion of animals presenting with M. bovis culture confirmed lesions in vaccinated Zone C (9%) compared with non-vaccinated Zone A (26%). These results demonstrate that oral BCG vaccination confers protection to badgers and could be used to reduce incident rates in tuberculosis-infected populations of badgers.
进行了一项田间试验，以研究对自由生活的獾进行口服疫苗接种对自然传播的牛分枝杆菌感染的影响。在三年时间里，在三个区域进行了七次捕捉獾的行动，并将其分为两组，分别口服脂质包裹的卡介苗（Liporale-BCG）或安慰剂。A区的獾接受安慰剂治疗，而C区的所有獾都接种了卡介苗。位于中间区域的B区的獾被随机分配，50%接受疫苗治疗，50%接受安慰剂治疗。每个区域的治疗在研究期结束前一直保持盲态。感兴趣的结果是结核病的发病情况，通过使用BrockTB Stat-Pak侧向流动血清学检测来测量血清转化事件的时间，并辅以尸检。在血清转化的接种疫苗的獾中，血清转化的中位时间（413天）与未接种疫苗的动物（230天）相比显著更长（p = 0.04）。生存分析（模拟血清转化时间）显示，在整个试验期间，A区和C区接种疫苗和未接种疫苗的獾之间的血清转化率存在显著差异（p = 0.015）。对于在第1 - 2次捕捉行动中纳入的獾，根据风险率比确定的疫苗效力（VE）为36%（95% CI：-62% - 75%）。对于在第3 - 6次捕捉行动中纳入这些区域的獾，VE为84%（95% CI：29% - 97%）。这表明疫苗效力随着疫苗接种覆盖率的提高而增加。试验结束时对獾的尸检还显示，接种疫苗的C区出现牛分枝杆菌培养确诊病变的动物比例（9%）与未接种疫苗的A区（26%）相比存在显著差异。这些结果表明，口服卡介苗接种可为獾提供保护，并可用于降低獾结核病感染群体的发病率。
