Data_Sheet_1_Immune cell early activation, apoptotic kinetic, and T-cell functional impairment in domestic pigs after ASFV CADC_HN09 strain infection.docx

African swine fever (ASF) caused by the African swine fever virus (ASFV) is a fatal and highly contagious disease of domestic pigs characterized by rapid disease progression and death within 2 weeks. How the immune cells respond to acute ASFV infection and contribute to the immunopathogenesis of ASFV has not been completely understood. In this study, we examined the activation, apoptosis, and functional changes of distinct immune cells in domestic pigs following acute infection with the ASFV CADC_HN09 strain using multicolor flow cytometry. We found that ASFV infection induced broad apoptosis of DCs, monocytes, neutrophils, and lymphocytes in the peripheral blood of pigs over time. The expression of MHC class II molecule (SLA-DR/DQ) on monocytes and conventional DCs as well as CD21 expression on B cells were downregulated after ASFV infection, implying a potential impairment of antigen presentation and humoral response. Further examination of CD69 and ex vivo expression of IFN-γ on immune cells showed that T cells were transiently activated and expressed IFN-γ as early as 5 days post-infection. However, the capability of T cells to produce cytokines was significantly impaired in the infected pigs when stimulated with mitogen. These results suggest that the adaptive cellular immunity to ASFV might be initiated but later overridden by ASFV-induced immunosuppression. Our study clarified the cell types that were affected by ASFV infection and contributed to lymphopenia, improving our understanding of the immunopathogenesis of ASFV.

非洲猪瘟（ASF），由非洲猪瘟病毒（ASFV）引起，是一种对家猪具有致命性和高度传染性的疾病，其特征为疾病进展迅速，病猪在两周内死亡。对于免疫细胞如何应对急性ASFV感染以及如何导致ASFV的免疫病理学尚不完全明了。在本研究中，我们利用多色流式细胞术，考察了家猪在急性感染ASFV CADC_HN09株后，不同免疫细胞的激活、凋亡和功能变化。我们发现，随着时间推移，ASFV感染诱导了猪外周血中DCs、单核细胞、中性粒细胞和淋巴细胞的广泛凋亡。ASFV感染后，单核细胞和传统DCs上MHC II类分子（SLA-DR/DQ）的表达以及B细胞上的CD21表达下调，这暗示了抗原呈递和体液反应可能存在潜在障碍。进一步对CD69和免疫细胞体外IFN-γ表达的研究表明，T细胞在感染后5天即开始短暂激活并表达IFN-γ。然而，在受到有丝分裂原刺激时，感染猪的T细胞产生细胞因子的能力显著受损。这些结果表明，对ASFV的适应性细胞免疫可能已被ASFV诱导的免疫抑制所超越。本研究阐明了受ASFV感染影响的细胞类型，并有助于理解淋巴细胞性减少的免疫病理学机制。