Knight-Jones T J D, Bulut A N, Gubbins S, Stärk K D C, Pfeiffer D U, Sumption K J, Paton D J
The Pirbright Institute, Pirbright, UK; The Royal Veterinary College (VEEPH), University of London, UK.
The Şap institute, Ankara, Turkey.
Vaccine. 2015 Feb 4;33(6):805-11. doi: 10.1016/j.vaccine.2014.12.010. Epub 2014 Dec 17.
Despite years of biannual mass vaccination of cattle, foot-and-mouth disease (FMD) remains uncontrolled in Anatolian Turkey. To evaluate protection after mass vaccination we measured post-vaccination antibodies in a cohort of cattle (serotypes O, A and Asia-1). To obtain results reflecting typical field protection, participants were randomly sampled from across Central and Western Turkey after routine vaccination. Giving two-doses one month apart is recommended when cattle are first vaccinated against FMD. However, due to cost and logistics, this is not routinely performed in Turkey, and elsewhere. Nested within the cohort, we conducted a randomised trial comparing post-vaccination antibodies after a single-dose versus a two-dose primary vaccination course. Four to five months after vaccination, only a third of single-vaccinated cattle had antibody levels above a threshold associated with protection. A third never reached this threshold, even at peak response one month after vaccination. It was not until animals had received three vaccine doses in their lifetime, vaccinating every six months, that most (64% to 86% depending on serotype) maintained antibody levels above this threshold. By this time cattle would be >20 months old with almost half the population below this age. Consequently, many vaccinated animals will be unprotected for much of the year. Compared to a single-dose, a primary vaccination course of two-doses greatly improved the level and duration of immunity. We concluded that the FMD vaccination programme in Anatolian Turkey did not produce the high levels of immunity required. Higher potency vaccines are now used throughout Turkey, with a two-dose primary course in certain areas. Monitoring post-vaccination serology is an important component of evaluation for FMD vaccination programmes. However, consideration must be given to which antigens are present in the test, the vaccine and the field virus. Differences between these antigens affect the relationship between antibody titre and protection.
尽管多年来对牛进行了每半年一次的大规模疫苗接种，但口蹄疫（FMD）在土耳其安纳托利亚地区仍未得到控制。为了评估大规模疫苗接种后的保护效果，我们测量了一组牛（O型、A型和亚洲1型血清型）接种疫苗后的抗体。为了获得反映典型田间保护效果的结果，在常规疫苗接种后，从土耳其中部和西部随机抽取参与者。首次给牛接种口蹄疫疫苗时，建议间隔一个月接种两剂。然而，由于成本和后勤问题，在土耳其及其他地方，这并非常规操作。在该队列中，我们进行了一项随机试验，比较单剂量与两剂量初次疫苗接种疗程后接种疫苗的抗体情况。接种疫苗四至五个月后，仅三分之一单剂量接种的牛的抗体水平高于与保护相关的阈值。三分之一的牛即使在接种疫苗一个月后的峰值反应时也从未达到该阈值。直到动物一生中接种了三剂疫苗，每六个月接种一次，大多数（根据血清型不同为64%至86%）才将抗体水平维持在该阈值以上。到那时，牛将超过20个月大，几乎一半的牛群低于这个年龄。因此，许多接种疫苗的动物在一年中的大部分时间里都没有得到保护。与单剂量相比，两剂量的初次疫苗接种疗程大大提高了免疫水平和持续时间。我们得出结论，土耳其安纳托利亚地区的口蹄疫疫苗接种计划未能产生所需的高免疫水平。现在土耳其各地都使用了效力更高的疫苗，在某些地区采用两剂量的初次疗程。监测接种疫苗后的血清学是口蹄疫疫苗接种计划评估的重要组成部分。然而，必须考虑检测、疫苗和田间病毒中存在哪些抗原。这些抗原之间的差异会影响抗体滴度与保护之间的关系。
