Orsel K, Dekker A, Bouma A, Stegeman J A, de Jong M C M
Faculty of Veterinary Medicine, Department of Farm Animal Health, Utrecht University, Yalelaan 7-9, 3584 Utrecht, CL, The Netherlands.
Vaccine. 2005 Sep 30;23(41):4887-94. doi: 10.1016/j.vaccine.2005.05.014.
The aim of vaccination during an epidemic of foot and mouth disease (FMD) is not to induce clinical protection, but to reduce virus transmission. Since no quantitative data were available on the effectiveness of vaccination in cattle, we investigated whether a single vaccination against FMD could reduce virus transmission in groups of calves by estimating the reproduction ratio R, i.e. the average number of secondary cases caused by one infectious animal in a susceptible population. We performed two experiments with six groups of either four vaccinated or four non-vaccinated calves each. Vaccination was carried out with O(1) Manisa vaccine. Two weeks after vaccination, two calves per group were inoculated intra-nasally with FMDV field isolate O/NET 2001. The two other calves were contact-exposed to the inoculated calves. Contact infections were observed by clinical inspection, virus isolation and RT-PCR on heparinised blood, oro-pharyngeal fluid and probang samples and antibody response to non-structural proteins. In all six non-vaccinated groups, transmission to contact-exposed calves was recorded; in the vaccinated groups, virus transmission was observed to one contact-exposed calf. In the non-vaccinated groups R(c) was 2.52 and significantly above 1, whereas in the vaccinated groups R(v)=0.18 and significantly below 1, indicating that vaccination may successfully be applied as additional intervention tool to reduce virus transmission in a future epidemic of FMD.
在口蹄疫（FMD）流行期间进行疫苗接种的目的不是诱导临床保护，而是减少病毒传播。由于没有关于牛群疫苗接种效果的定量数据，我们通过估计繁殖率R（即易感群体中一只感染动物引起的二代病例的平均数量）来研究针对口蹄疫的单次疫苗接种是否能降低犊牛群体中的病毒传播。我们进行了两组实验，每组有六组，每组分别有四只接种疫苗或四只未接种疫苗的犊牛。使用O（1）马尼萨疫苗进行接种。接种疫苗两周后，每组两只犊牛经鼻内接种口蹄疫病毒野毒株O/NET 2001。另外两只犊牛与接种的犊牛进行接触感染。通过临床检查、病毒分离以及对肝素化血液、口咽液和探条样本进行逆转录聚合酶链反应（RT-PCR）以及对非结构蛋白的抗体反应来观察接触感染情况。在所有六个未接种疫苗的组中，均记录到向接触感染犊牛的病毒传播；在接种疫苗的组中，仅观察到一只接触感染犊牛出现病毒传播。在未接种疫苗的组中，R（c）为2.52，显著高于1，而在接种疫苗的组中，R（v）=0.18，显著低于1，这表明在未来口蹄疫流行时，疫苗接种可作为一种额外的干预手段成功用于减少病毒传播。
