Australian Animal Health Laboratory, CSIRO-Health and Biosecurity, Geelong, Australia.
Plum Island Animal Disease Center, USDA-ARS, Orient Point, New York, USA.
Antiviral Res. 2017 Sep;145:114-122. doi: 10.1016/j.antiviral.2017.07.020. Epub 2017 Aug 3.
Potency tests for commercial oil-adjuvanted foot-and-mouth disease (FMD) vaccines are usually carried out in cattle, using a full dose (2 ml) of vaccine and homologous virus challenge. However, in sheep the recommended vaccine dose is half of the cattle dose (1 ml) and most vaccines have not been potency tested for this species, especially with heterologous viruses. To determine the efficacy of a high potency (>6PD) FMD virus (FMDV) O1Manisa vaccine in sheep, we carried out a study using a heterologous FMDV (FMDV O/SKR/2010 - Mya-98 strain) challenge. Groups of seven animals each were vaccinated with 2×, 1×, 1/2× or 1/4× dose (2 ml, 1 ml, 0.5 ml or 0.25 ml respectively) and challenged at 7 days post vaccination (dpv). Only 3 of the 7 sheep in the group vaccinated with 2 ml were protected. With 2 additional groups, receiving double or single doses and challenged at 14 dpv, 4 of 7 sheep were protected in each group. None of the sheep had measurable neutralising antibodies against the vaccine or challenge virus at 7 dpv. However, all vaccinated animals challenged at 14 dpv had a homologous neutralising response against FMDV O1 Manisa on the day of challenge and all but one animal also had a heterologous response to FMDV O/SKR/2010. Infectious FMDV and viral RNA could be found in nasal swabs between 1 and 6 days post challenge (dpc) in most vaccinated sheep, but those vaccinated with higher doses or challenged at 14 dpv showed significant decreases in the level of FMDV detection. Intermittent virus shedding was noticed between 1 and 35 dpc in all vaccinated groups, but persistent infection could be demonstrated only in 4 sheep (20%). This study showed that at the recommended dose, a high potency (>6 PD) FMDV O1Manisa vaccine does not protect sheep against a heterologous challenge at 7 dpv. However, partial protection was observed when a double dose was used at 7 dpv or when double or single dose vaccinated sheep were challenged at 14 dpv.
商业佐剂口蹄疫（FMD）疫苗的效力测试通常在牛中进行，使用全剂量（2 毫升）疫苗和同源病毒挑战。然而，在绵羊中，推荐的疫苗剂量是牛剂量的一半（1 毫升），并且大多数疫苗尚未针对该物种进行效力测试，尤其是针对异源病毒。为了确定高效力（>6PD）FMD 病毒（FMDV）O1Manisa 疫苗在绵羊中的功效，我们使用异源 FMDV（FMDV O/SKR/2010-Mya-98 株）进行了一项研究。每组 7 只动物分别接受 2×、1×、1/2×或 1/4×剂量（2 毫升、1 毫升、0.5 毫升或 0.25 毫升）接种，并在接种后 7 天（dpv）进行攻毒。仅在接受 2 毫升接种的 7 只绵羊中有 3 只受到保护。在另外 2 个组中，每组接受双剂量或单剂量接种，并在 14 dpv 进行攻毒，每组有 7 只绵羊中的 4 只受到保护。在 7 dpv 时，没有绵羊对疫苗或攻毒病毒产生可测量的中和抗体。然而，所有在 14 dpv 接种并攻毒的动物在攻毒当天都对 FMDV O1 Manisa 产生了同源中和反应，除 1 只动物外，所有动物对 FMDV O/SKR/2010 也产生了异源反应。在大多数接种绵羊中，攻毒后 1 至 6 天（dpc）可在鼻拭子中检测到传染性 FMDV 和病毒 RNA，但接种较高剂量或在 14 dpv 攻毒的动物显示出 FMDV 检测水平的显著降低。在所有接种组中，攻毒后 1 至 35 dpc 期间都观察到间歇性病毒排出，但仅在 4 只绵羊（20%）中可以证明持续性感染。本研究表明，在推荐剂量下，高效力（>6PD）FMDV O1Manisa 疫苗不能保护绵羊免受 7 dpv 的异源攻毒。然而，当在 7 dpv 时使用双剂量，或当在 14 dpv 时接种双剂量或单剂量的绵羊进行攻毒时，观察到部分保护。
