Wichgers Schreur Paul J, Oymans Judith, Kant Jet, van de Water Sandra, Kollár Anna, Dehon Yves, Soós Pál, Pénzes Zoltán, van Keulen Lucien, Kortekaas Jeroen
Department of Virology, Wageningen Bioveterinary Research, Wageningen University and Research, Lelystad, The Netherlands.
BunyaVax B.V., Lelystad, The Netherlands.
NPJ Vaccines. 2021 Jan 8;6(1):8. doi: 10.1038/s41541-020-00271-7.
Rift Valley fever virus (RVFV) is a mosquito-transmitted bunyavirus that causes severe outbreaks among wild and domesticated ruminants, of which sheep are the most susceptible. Outbreaks are characterised by high mortality rates among new-born lambs and abortion storms, in which all pregnant ewes in a flock may abort their foetuses. In endemic areas, Rift Valley fever (RVF) can be controlled by vaccination with either inactivated or live-attenuated vaccines. Inactivated vaccines are safe for animals during all physiological stages, including pregnancy. However, optimal efficacy of these vaccines depends on multiple vaccinations and yearly re-vaccination. Live-attenuated vaccines are generally highly efficacious after a single vaccination, but currently available live-attenuated vaccines may transmit to the ovine foetus, resulting in stillbirths, congenital malformations or abortion. We have previously reported the development of a novel live-attenuated RVFV vaccine, named RVFV-4s. This vaccine virus was created by splitting the M genome segment and deleting the major virulence determinant NSs, and was shown to be safe even for the most susceptible species, including pregnant ewes. The demonstrated efficacy and safety profile suggests that RVFV-4s holds promise for veterinary and human application. The RVFV-4s vaccine for veterinary application, here referred to as vRVFV-4s, was shown to provide complete protection after a single vaccination of lambs, goats and cattle. In this work, we evaluated the efficacy of the vRVFV-4s vaccine in pregnant ewes. Anticipating on the extremely high susceptibility of pregnant ewes for RVFV, both a single vaccination and double vaccination were evaluated in two independent experiments. The combined results suggest that a single vaccination with vRVFV-4s is sufficient to protect pregnant ewes and to prevent transmission to the ovine foetus.
裂谷热病毒（RVFV）是一种由蚊子传播的布尼亚病毒，可在野生和家养反刍动物中引发严重疫情，其中绵羊最为易感。疫情的特征是新生羔羊死亡率高以及流产风暴，即一群中的所有怀孕母羊都可能流产。在流行地区，裂谷热（RVF）可通过接种灭活疫苗或减毒活疫苗来控制。灭活疫苗在包括怀孕期在内的所有生理阶段对动物都是安全的。然而，这些疫苗的最佳效力取决于多次接种和每年重新接种。减毒活疫苗通常在单次接种后具有高效力，但目前可用的减毒活疫苗可能会传播给绵羊胎儿，导致死产、先天性畸形或流产。我们之前报道了一种新型减毒活RVFV疫苗的研发，名为RVFV-4s。这种疫苗病毒是通过拆分M基因组片段并删除主要毒力决定因素NSs而产生的，并且已证明即使对包括怀孕母羊在内的最易感物种也是安全的。已证明的效力和安全性表明RVFV-4s在兽医和人类应用方面具有前景。用于兽医应用的RVFV-4s疫苗，在此称为vRVFV-4s，在对羔羊、山羊和牛进行单次接种后显示能提供完全保护。在这项工作中，我们评估了vRVFV-4s疫苗在怀孕母羊中的效力。鉴于怀孕母羊对RVFV的极高易感性，在两个独立实验中对单次接种和两次接种都进行了评估。综合结果表明，用vRVFV-4s进行单次接种足以保护怀孕母羊并防止传播给绵羊胎儿。
