College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou 225009, PR China.
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225009, PR China.
J Gen Virol. 2023 May;104(5). doi: 10.1099/jgv.0.001850.
Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most devastating pathogens to the global swine industry. Many commercial PRRSV vaccines, originally designed to provide homologous protection, have shown partial protection against heterologous strains. However, the protective immune mechanisms mediated by these PRRSV vaccines are not fully understood. In this study, we investigated the factors responsible for partial protection conferred by an attenuated Chinese HP-PRRSV vaccine (TJM-F92) against heterologous NADC30-like PRRSV. By analysing peripheral T-cell responses induced by the TJM-F92 vaccine and local and systemic memory responses following challenge with NADC30-like PRRSV (SD17-38 strains) as well as neutralizing antibody response, we found that the TJM-F92 vaccine induced a significant expansion of CD8 T cells but not CD4 T cells or γδ T cells. The expanded CD8 T cells exhibited a phenotype of effector memory T cells and secreted IFN-γ upon restimulation with SD17-38 strains . In addition, only CD8 T cells in the prior immunized pigs rapidly expanded in the blood and spleen after heterologous challenge, with higher magnitude, compared to the unvaccinated pigs, showing a remarkable memory response. In contrast, no obvious humoral immune response was enhanced in the vaccinated and challenged pigs, and no heterologous neutralizing antibodies were detected throughout the experiment. Our results suggested that CD8 T cells elicited by the TJM-F92 vaccine may be responsible for partial heterologous protection against NADC30-like PRRSV strains and potentially recognize the conserved antigens among PRRSV strains.
猪繁殖与呼吸综合征病毒（PRRSV）是全球养猪业最具破坏性的病原体之一。许多最初设计用于提供同源保护的商业 PRRSV 疫苗对异源毒株显示出部分保护作用。然而，这些 PRRSV 疫苗介导的保护性免疫机制尚未完全了解。在这项研究中，我们研究了减毒中国 HP-PRRSV 疫苗（TJM-F92）对异源 NADC30 样 PRRSV 产生部分保护作用的原因。通过分析 TJM-F92 疫苗诱导的外周 T 细胞反应以及用 NADC30 样 PRRSV（SD17-38 株）攻毒后诱导的局部和全身记忆反应以及中和抗体反应，我们发现 TJM-F92 疫苗诱导了显著的 CD8 T 细胞扩增，但没有 CD4 T 细胞或 γδ T 细胞。扩增的 CD8 T 细胞表现出效应记忆 T 细胞的表型，在用 SD17-38 株再刺激时分泌 IFN-γ。此外，只有先前免疫的猪在异源攻毒后，其血液和脾脏中的 CD8 T 细胞迅速扩增，与未接种疫苗的猪相比，扩增幅度更大，表现出显著的记忆反应。相比之下，接种和攻毒的猪中没有明显增强的体液免疫反应，整个实验过程中未检测到异源中和抗体。我们的结果表明，TJM-F92 疫苗诱导的 CD8 T 细胞可能是对 NADC30 样 PRRSV 株产生部分异源保护的原因，并且可能识别 PRRSV 株之间的保守抗原。
