Peta Faith R M, Sirdar M M, van Bavel Peter, Mutowembwa P B, Visser N, Olowoyo J, Seheri M, Heath Livio
Transboundary Animal Diseases: Vaccine Production Programme, Onderstepoort Veterinary Research Institute, Agricultural Research Council, Pretoria, South Africa.
Department of Medical Virology, School of Medicine, Sefako Makgatho Health Sciences University, Pretoria, South Africa.
Front Vet Sci. 2021 Dec 15;8:750223. doi: 10.3389/fvets.2021.750223. eCollection 2021.
South Africa (SA) experiences sporadic foot and mouth disease (FMD) outbreaks irrespective of routine prophylactic vaccinations of cattle using imported commercial vaccines. The problem could be mitigated by preparation of vaccines from local virus strains related to those circulating in the endemically infected buffalo populations in the Kruger National Park (KNP). This study demonstrates the individual number of protective doses (PD) of five vaccine candidate strains after homologous virus challenge, as well as the vaccines safety and onset of humoral immunity in naïve cattle. Furthermore, the duration of post-vaccination immunity over a 12-month period is shown, when a multivalent vaccine prepared from the five strains is administered as a primary dose with or without booster vaccinations. The five monovalent vaccines were shown to contain a 50% PD between 4 and 32, elicit humoral immunity with antibody titers ≥2.0 log10 from day 7 post-vaccination, and cause no adverse reactions. Meanwhile, the multivalent vaccine elicited antibody titers ≥2.0 log10 and clinical protection up to 12 months when one or two booster vaccinations were administered within 6 months of the primary vaccination. An insignificant difference between the application of one or two booster vaccinations was revealed. Owing to the number of PDs, we anticipate that the multivalent vaccine could be used successfully for prophylactic and emergency vaccinations without adjustment of the antigen payloads. Furthermore, a prophylactic vaccination regimen comprising primary vaccination of naïve cattle followed by two booster vaccinations 1.5 and 6 months later could potentially maintain herd immunity over a period of 12 months.
南非（SA）无论使用进口商业疫苗对牛进行常规预防性接种，仍会不时爆发口蹄疫（FMD）疫情。通过使用与克鲁格国家公园（KNP）地方性感染水牛群体中流行的病毒株相关的本地病毒株制备疫苗，这一问题有望得到缓解。本研究展示了五种候选疫苗毒株在同源病毒攻击后的个体保护剂量（PD）数量，以及在未接触过疫苗的牛群中的疫苗安全性和体液免疫的起始情况。此外，还展示了在接种由这五种毒株制备的多价疫苗作为初免剂量（有无加强免疫）后，12个月内的疫苗接种后免疫持续时间。结果表明，这五种单价疫苗的50%保护剂量在4至32之间，接种后第7天即可诱导抗体滴度≥2.0 log10的体液免疫，且无不良反应。同时，在初免后6个月内进行一次或两次加强免疫时，多价疫苗可诱导抗体滴度≥2.0 log10并提供长达12个月的临床保护。一次或两次加强免疫的应用之间差异不显著。鉴于保护剂量的数量，我们预计多价疫苗无需调整抗原含量即可成功用于预防性和紧急接种。此外，一种预防性接种方案，即对未接触过疫苗的牛进行初免，随后在1.5个月和6个月后进行两次加强免疫，有可能在12个月内维持畜群免疫力。
