ABSTRACT

BBIBP-CorV exerts efficient protection against SARS-CoV-2 infection. However, waning vaccine-induced humoral immune responses after two-dose vaccination have significantly undermined durable immuno-protection. In this study, we have demonstrated that although anti-spike (S) antibody responses in BBIBP-CorV vaccinees exhibited three serotypes after 6 months, including de novo sero-negative, sero-positive, and sero-decay features, S-specific interferon-γ release as well as Th1 cytokine production in CD4⁺ and CD8⁺ T cells were comparable, especially in vaccinees without detectable neutralizing antibodies. Notably, regardless of dramatic increases in humoral immunity after booster vaccination, T cell responses targeting S protein from either wild type or Omicron remained stable before and after booster vaccination in all three serotype vaccinees. No severe cases were observed even in the sero-decay group during the Omicron epidemic in Shanghai. Our results thus illustrate that unlike fluctuating humoral responses, viral-specific T cell responses are extremely stable after booster vaccination. Sustained T cell responses might be dedicated to the rapid restoration of antibody responses after booster vaccination.

摘要

BBIBP-CorV 对 SARS-CoV-2 感染发挥有效保护作用。然而，两剂疫苗接种后疫苗诱导的体液免疫反应减弱，显着破坏了持久的免疫保护。在这项研究中，我们已经证明，尽管 BBIBP-CorV 疫苗接种者的抗尖峰 (S) 抗体反应在 6 个月后表现出三种血清型，包括从头血清阴性、血清阳性和血清衰变特征，但 S 特异性干扰素CD4 ⁺和 CD8 ⁺中的 -γ 释放以及 Th1 细胞因子的产生T 细胞具有可比性，尤其是在没有可检测到中和抗体的疫苗接种者中。值得注意的是，无论加强疫苗接种后体液免疫是否显着增加，针对野生型或 Omicron 的 S 蛋白的 T 细胞反应在所有三种血清型疫苗加强疫苗接种前后都保持稳定。上海Omicron疫情期间，即使血清衰变组也未观察到重症病例。因此，我们的结果表明，与波动的体液反应不同，病毒特异性 T 细胞反应在加强疫苗接种后非常稳定。持续的 T 细胞反应可能专用于加强疫苗接种后抗体反应的快速恢复。