Key Laboratory of Veterinary Biotechnology, Faculty of Veterinary Medicine, Vietnam National University of Agriculture, Gia Lam, Ha Noi 12406, Vietnam.
Center on Biologics Development and Evaluation, Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
Viruses. 2024 Aug 19;16(8):1326. doi: 10.3390/v16081326.
African swine fever (ASF) is a highly contagious and severe hemorrhagic transboundary swine viral disease with up to a 100% mortality rate, which leads to a tremendous socio-economic loss worldwide. The lack of safe and efficacious ASF vaccines is the greatest challenge in the prevention and control of ASF. In this study, we generated a safe and effective live-attenuated virus (LAV) vaccine candidate VNUA-ASFV-LAVL3 by serially passaging a virulent genotype II strain (VNUA-ASFV-L2) in an immortalized porcine alveolar macrophage cell line (3D4/21, 50 passages). VNUA-ASFV-LAVL3 lost its hemadsorption ability but maintained comparable growth kinetics in 3D4/21 cells to that of the parental strain. Notably, it exhibited significant attenuation of virulence in pigs across different doses (10, 10, and 10 TCID). All vaccinated pigs remained healthy with no clinical signs of African swine fever virus (ASFV) infection throughout the 28-day observation period of immunization. VNUA-ASFV-LAVL3 was efficiently cleared from the blood at 14-17 days post-infection, even at the highest dose (10 TCID). Importantly, the attenuation observed in vivo did not compromise the ability of VNUA-ASFV-LAVL3 to induce protective immunity. Vaccination with VNUA-ASFV-LAVL3 elicited robust humoral and cellular immune responses in pigs, achieving 100% protection against a lethal wild-type ASFV (genotype II) challenge at all tested doses (10, 10, and 10 TCID). Furthermore, a single vaccination (10 TCID) provided protection for up to 2 months. These findings suggest that VNUA-ASFV-LAVL3 can be utilized as a promising safe and efficacious LAV candidate against the contemporary pandemic genotype II ASFV.
非洲猪瘟（ASF）是一种具有高度传染性和严重出血性的跨界猪病毒性疾病，死亡率高达 100%，给全球造成了巨大的社会经济损失。缺乏安全有效的 ASF 疫苗是 ASF 预防和控制的最大挑战。在本研究中，我们通过在永生化猪肺泡巨噬细胞系（3D4/21，50 代）中连续传代一株强毒基因型 II 株（VNUA-ASFV-L2），生成了一种安全有效的减毒活病毒（LAV）疫苗候选株 VNUA-ASFV-LAVL3。VNUA-ASFV-LAVL3 丧失了其红细胞吸附能力，但在 3D4/21 细胞中的生长动力学与亲本株相当。值得注意的是，它在不同剂量（10、10 和 10 TCID）下在猪中的毒力显著降低。所有接种疫苗的猪在整个 28 天的免疫观察期内均保持健康，没有 ASF 感染的临床症状。VNUA-ASFV-LAVL3 在感染后 14-17 天从血液中被有效清除，即使在最高剂量（10 TCID）下也是如此。重要的是，体内观察到的减毒作用并未削弱 VNUA-ASFV-LAVL3 诱导保护性免疫的能力。VNUA-ASFV-LAVL3 疫苗接种在猪中引起了强烈的体液和细胞免疫反应，在所有测试剂量（10、10 和 10 TCID）下均能实现 100%的保护，免受致死性野生型 ASFV（基因型 II）的攻击。此外，单次接种（10 TCID）可提供长达 2 个月的保护。这些发现表明，VNUA-ASFV-LAVL3 可用作针对当代流行基因型 II ASFV 的有前途的安全有效的 LAV 候选疫苗。
