Laboratory of Animal Infectious Disease, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, Xinjiang Uygur Autonomous Region, China.
Chinese Academy of Sciences (CAS) Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.
Front Immunol. 2024 Jul 3;15:1408510. doi: 10.3389/fimmu.2024.1408510. eCollection 2024.
Equid alphaherpesvirus 1 (EqAHV1) is a viral pathogen known to cause respiratory disease, neurologic syndromes, and abortion storms in horses. Currently, there are no vaccines that provide complete protection against EqAHV1. Marker vaccines and the differentiation of infected and vaccinated animals (DIVA) strategy are effective for preventing and controlling outbreaks but have not been used for the prevention of EqAHV1 infection. Glycoprotein 2 (gp2), located on the envelope of viruses (EqAHV1), exhibits high antigenicity and functions as a molecular marker for DIVA. In this study, a series of EqAHV1 mutants with deletion of gp2 along with other virulence genes (TK, UL24/TK, gI/gE) were engineered. The mutant viruses were studied and then in an experiment using Golden Syrian hamsters to assess the extent of viral attenuation and the immune response elicited by the mutant viruses in comparison to the wild-type (WT) virus. Compared with the WT strain, the YM2019 Δgp2, ΔTK/gp2, and ΔUL24/TK/gp2 strains exhibited reduced growth in RK-13 cells, while the ΔgI/gE/gp2 strain exhibited significantly impaired proliferation. The YM2019 Δgp2 strain induced clinical signs and mortality in hamsters. In contrast, the YM2019 ΔTK/gp2 and ΔUL24/TK/gp2 variants displayed diminished pathogenicity, causing no observable clinical signs or fatalities. Immunization with nasal vaccines containing YM2019 ΔTK/gp2 and ΔUL24/TK/gp2 elicited a robust immune response in hamsters. In particular, compared with the vaccine containing the ΔTK/gp2 strain, the vaccine containing the ΔUL24/TK/gp2 strain demonstrated enhanced immune protection upon challenge with the WT virus. Furthermore, an ELISA for gp2 was established and refined to accurately differentiate between infected and vaccinated animals. These results confirm that the ΔUL24/TK/gp2 strain is a safe and effective live attenuated vaccine candidate for controlling EqAHV1 infection.
马疱疹病毒 1 型（EqAHV1）是一种已知可引起马呼吸道疾病、神经综合征和流产风暴的病毒病原体。目前，尚无针对 EqAHV1 的完全保护疫苗。标记疫苗和区分感染和接种动物（DIVA）策略可有效预防和控制疫情爆发，但尚未用于预防 EqAHV1 感染。糖蛋白 2（gp2）位于病毒（EqAHV1）的包膜上，具有高抗原性，可作为 DIVA 的分子标记。在本研究中，构建了一系列缺失 gp2 及其他毒力基因（TK、UL24/TK、gI/gE）的 EqAHV1 突变体。通过对突变病毒的研究，并在一项使用金黄地鼠的实验中，评估了突变病毒相对于野生型（WT）病毒的病毒衰减程度和免疫反应。与 WT 株相比，YM2019Δgp2、ΔTK/gp2 和ΔUL24/TK/gp2 株在 RK-13 细胞中的生长能力降低，而ΔgI/gE/gp2 株的增殖能力显著受损。YM2019Δgp2 株在金黄地鼠中引起临床症状和死亡。相比之下，YM2019ΔTK/gp2 和ΔUL24/TK/gp2 变异株的致病性降低，未观察到临床症状或死亡。鼻腔疫苗免疫金黄地鼠可引起强烈的免疫反应。特别是，与含ΔTK/gp2 株的疫苗相比，含ΔUL24/TK/gp2 株的疫苗在接种 WT 病毒后显示出增强的免疫保护作用。此外，建立并优化了针对 gp2 的 ELISA，以准确区分感染和接种动物。这些结果证实，ΔUL24/TK/gp2 株是控制 EqAHV1 感染的安全有效的活减毒候选疫苗。
