Vaxine Pty Ltd, Adelaide, South Australia, Australia.
Flinders University, Adelaide, South Australia, Australia.
Immunology. 2023 Oct;170(2):193-201. doi: 10.1111/imm.13661. Epub 2023 May 18.
SpikoGen® vaccine is a subunit COVID-19 vaccine expressed in insect cells comprising recombinant spike protein extracellular domain formulated with Advax-CpG55.2™ adjuvant. A Phase 2 trial was conducted in 400 adult participants randomised 3:1 to receive two intramuscular doses of SpikoGen® vaccine or saline placebo 3 weeks apart. Some Phase 2 trial participants later enrolled in a separate booster study and received a third dose of SpikoGen® vaccine. This stored serum was used to assess the ability of SpikoGen® vaccine to induce cross-neutralising antibodies against SARS-CoV-2 variants of concern. Sera taken at baseline and 2 weeks after the second vaccine dose from baseline seronegative Phase 2 subjects was evaluated using a panel of spike pseudotype lentivirus neutralisation assays for the ability to cross-neutralise a wide range of SARS-CoV-2 variants, including Omicron BA.1, BA.2 and BA.4/5. Stored samples of subjects who participated in both the 2-dose Phase 2 trial and a third dose booster trial 6 months later were also analysed for changes in cross-neutralising antibodies over time and dose. Two weeks after the second dose, sera broadly cross-neutralised most variants of concern, albeit with titres against Omicron variants being ~10-fold lower. While Omicron titres fell to low levels 6 months after the second vaccine dose in most subjects, they showed a ~20-fold rise after the third dose booster, after which there was only a ~2-3-fold difference in neutralisation of Omicron and the ancestral strains. Despite being based on the ancestral Wuhan sequence, after two doses, SpikoGen® vaccine induced broadly cross-neutralising serum antibodies. Titres then reduced over time but were rapidly restored by a third dose booster. This resulted in high neutralisation including against the Omicron variants. This data supports ongoing use of SpikoGen® vaccine for protection against recent SARS-CoV-2 Omicron variants.
斯皮科根（SpikoGen）®疫苗是一种基于昆虫细胞表达的亚单位 COVID-19 疫苗，包含重组刺突蛋白胞外结构域，与 Advax-CpG55.2™佐剂联合配制。一项 400 名成年参与者参与的 2 期临床试验中，参与者被随机分为 3:1 组，分别接受 2 剂肌肉内斯皮科根（SpikoGen）®疫苗或生理盐水安慰剂，间隔 3 周。一些 2 期临床试验参与者随后参加了一项单独的加强研究，并接受了第 3 剂斯皮科根（SpikoGen）®疫苗。这些储存的血清用于评估斯皮科根（SpikoGen）®疫苗诱导针对 SARS-CoV-2 关注变体的交叉中和抗体的能力。在基线时以及在基线时血清学阴性的 2 期参与者接受第 2 剂疫苗后 2 周，使用一系列 Spike 假型慢病毒中和测定法评估血清对广泛的 SARS-CoV-2 变体的交叉中和能力，包括奥密克戎 BA.1、BA.2 和 BA.4/5。还分析了 6 个月后参加 2 剂 2 期试验和第 3 剂加强试验的参与者的储存样本，以评估随时间和剂量的交叉中和抗体的变化。在第 2 剂疫苗接种后 2 周，血清广泛交叉中和了大多数关注的变体，尽管针对奥密克戎变体的滴度低 10 倍。虽然大多数参与者在第 2 剂疫苗接种后 6 个月后奥密克戎滴度降至低水平，但在第 3 剂加强剂后滴度升高了约 20 倍，之后对奥密克戎和原始株的中和水平仅相差约 2-3 倍。尽管基于原始的武汉序列，但在接种两剂疫苗后，斯皮科根（SpikoGen）®疫苗诱导了广泛的交叉中和血清抗体。随后，抗体滴度随时间降低，但通过第 3 剂加强剂迅速恢复。这导致了高中和，包括对奥密克戎变体的中和。该数据支持继续使用斯皮科根（SpikoGen）®疫苗来预防最近的 SARS-CoV-2 奥密克戎变体。
