Institute of Preventive Veterinary Medicine, College of Animal Sciences of Zhejiang University, 866 Yuhangtang road, Hangzhou, 310058, China.
Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Hangzhou, China.
BMC Microbiol. 2020 Feb 4;20(1):26. doi: 10.1186/s12866-020-1713-2.
Outbreaks of Classical swine fever virus (CSFV) cause significant economic losses in the swine industry. Vaccination is the major method to prevent and control the disease. As live attenuated vaccines fail to elicit differentiable immunity between infected and vaccinated animals, subunit vaccine was considered as an alternative candidate to prevent and eradicate CSFV. Subunit vaccines present advantages in DIVA immunogenicity and safety. The technology was limited due to the low yield and the high cost with multiple and large doses. The native E2 signal peptide has not been well defined before. Here, the aim of this study is to develop a cost-effective and efficacious E2 vaccine candidate against CSFV with signal peptide and E2 sequence selection.
A novel CSFV E2 sequence (E2ZJ) was identified from an epidemic strain of Zhejiang for outstanding secretion in baculovirus and enhanced immunogenicity. E2 secretion induced with the selected signal peptide, SPZJ (SP23), increase at least 50% as compared to any other signal peptides tested. Besides, unique antigenic features were identified in E2ZJ. As indicated with immunized sera in IFA against CSFV infection, E2ZJ elicited CSFV antibodies at the earlier stage than other E2 types tested in mice. Moreover, higher level of neutralizing and CSFV antibodies against CSFV with E2ZJ was detected than other E2s with the same dosage at 28 dpi. Further, E2ZJ successfully elicited neutralizing immunity in piglets. A single dose of 5 μg of E2ZJ was sufficient to induce protective antibodies against CSFV in piglets and provided 100% protection against lethal virus challenge.
Our studies provide evidence that E2ZJ guided by a novel E2 signal peptide (SPZJ) was efficiently secreted and presented significantly improved immunogenicity than conventional E2 vaccines. Moreover, a single dose of 5 μg E2ZJ is efficacious against CSFV in piglets.
经典猪瘟病毒（CSFV）的爆发会给养猪业造成巨大的经济损失。接种疫苗是预防和控制该病的主要方法。由于活减毒疫苗不能在感染动物和接种动物之间产生可区分的免疫应答，因此亚单位疫苗被认为是预防和根除 CSFV 的替代候选疫苗。亚单位疫苗具有 DIVA 免疫原性和安全性优势。由于产量低、成本高、需要多次大剂量接种，该技术受到限制。天然 E2 信号肽以前没有得到很好的定义。本研究旨在通过选择信号肽和 E2 序列，开发一种具有成本效益且有效的针对 CSFV 的 E2 疫苗候选物。
从浙江流行株中鉴定出一种新型 CSFV E2 序列（E2ZJ），该序列在杆状病毒中具有出色的分泌能力和增强的免疫原性。与所测试的任何其他信号肽相比，选择的信号肽 SPZJ（SP23）诱导的 E2 分泌至少增加了 50%。此外，在 E2ZJ 中还鉴定出独特的抗原特征。IFA 中用免疫血清检测到针对 CSFV 感染的 E2ZJ，在小鼠中比其他 E2 类型更早地引发 CSFV 抗体。此外，在 28dpi 时，用相同剂量的 E2ZJ 检测到针对 CSFV 的中和抗体和 CSFV 抗体水平高于其他 E2 类型。此外，E2ZJ 成功在仔猪中诱导了中和免疫。仔猪只需单剂量 5μg 的 E2ZJ 即可诱导针对 CSFV 的保护性抗体，对致死性病毒攻击提供 100%的保护。
我们的研究表明，新型 E2 信号肽（SPZJ）指导的 E2ZJ 得到了有效的分泌，其免疫原性明显优于传统的 E2 疫苗。此外，仔猪中只需单剂量 5μg 的 E2ZJ 即可有效抵抗 CSFV。
