Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Gauteng, South Africa.
Equine Vet J. 2013 Sep;45(5):604-7. doi: 10.1111/evj.12015. Epub 2013 Jan 7.
African horse sickness is an insect-transmitted, noncontagious disease of equids caused by African horse sickness virus (AHSV). Mortality can exceed 90% in fully susceptible horse populations. A live-attenuated (modified live) cell-culture-adapted (MLV) polyvalent AHSV vaccine is widely used to control African horse sickness in endemic areas in southern Africa. Field studies detailing antibody responses of vaccinated horses are lacking.
To determine antibody titres to the 9 known serotypes of AHSV in a cohort of broodmares that were regularly vaccinated with the MLV AHSV vaccine and to measure the passive transfer and rate of decay of maternal antibody to the individual virus serotypes in foals.
Serum was collected from 15 mares before foaling and from their foals after foaling and monthly thereafter for 6 months. Antibody titres to each of the 9 AHSV serotypes were determined by serum virus neutralisation assay.
There was marked variation in the antibody response of the mares to individual AHSV serotypes even after repeated vaccination, with consistently higher titre responses to some virus serotypes. Likewise, the duration of maternally derived antibodies in foals differed among serotypes.
Data from this study confirm variation of the neutralising antibody response of individual mares to repeated vaccination with polyvalent AHSV vaccine. Virus strains of individual AHSV serotypes included in the vaccine may vary in their inherent immunogenicity. Passively acquired maternal antibodies to AHSV vary markedly among foals born to vaccinated mares, with further variation in the duration of passive immunity to individual AHSV serotypes.
These data are relevant to the effective utilisation of live-attenuated AHSV vaccines in endemic regions, and potentially to the use of vaccines in response to future incursions of AHSV into previously free regions. Further studies involving a larger population will be required to determine the optimal time for vaccinating foals.
非洲马瘟是一种由非洲马瘟病毒（AHSV）引起的昆虫传播、非接触性传染病，主要影响马科动物。在完全易感的马群中，死亡率超过 90%。一种活减毒（改良活）细胞培养适应（MLV）多价 AHSV 疫苗广泛用于控制南部非洲流行地区的非洲马瘟。缺乏详细描述接种马的抗体反应的田间研究。
确定定期接种 MLV AHSV 疫苗的母马群中对 9 种已知 AHSV 血清型的抗体滴度，并测量母马向幼驹个体病毒血清型的被动转移和母源抗体衰减率。
在分娩前和分娩后从 15 匹母马及其幼驹收集血清，并在随后的 6 个月内每月收集一次。通过血清病毒中和试验测定对 9 种 AHSV 血清型的抗体滴度。
即使经过多次接种，母马对个别 AHSV 血清型的抗体反应也存在明显差异，对某些病毒血清型的反应始终较高。同样，幼驹中母源抗体的持续时间也因血清型而异。
本研究的数据证实了个体母马对多价 AHSV 疫苗重复接种的中和抗体反应存在差异。疫苗中包含的个别 AHSV 血清型的病毒株在其固有免疫原性方面可能存在差异。接种母马所生幼驹获得的被动获得的 AHSV 抗体差异很大，对个别 AHSV 血清型的被动免疫持续时间也存在进一步的差异。
这些数据与在流行地区有效利用活减毒 AHSV 疫苗有关，并且可能与在未来 AHSV 侵入先前无病地区时使用疫苗有关。需要进一步的研究涉及更大的人群，以确定为幼驹接种疫苗的最佳时间。
