Xing Gang, Li Hui, Lu Chenhe, Li Haimin, Jin Yulan, Yan Yan, Shang Shaobin, Zhou Jiyong
MOA Key Laboratory of Animal Virology, Zhejiang University Center for Veterinary Sciences, Hangzhou, China.
Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.
Front Immunol. 2024 Dec 23;15:1489268. doi: 10.3389/fimmu.2024.1489268. eCollection 2024.
Pseudorabies virus (PRV), causing Aujeszky's disease in swine, has important economic impact on the pig industry in China and even poses a threat to public health. Although this disease has been controlled by vaccination with PRV live attenuated vaccines (LAVs), the potency of PRV LAVs in inducing cellular immunity has not been well characterized. In this study, using PRV Bartha K61 strain (BK61), the most-used PRV LAVs, as a model, we re-examined the cellular immune response elicited by the BK61 in mice and pigs by multicolor flow cytometry. We found that phenotypic activation of T cells, NK cells and B cells was hardly detected after vaccination. However, antigen-specific IFN-γ-producing CD4 T cells rather than CD8 T cells were dominantly detected but at low frequency upon restimulation with live BK61 virus. These BK61-specific CD4 T cells are also able to simultaneously produce TNF-α and IL-2, showing characteristics of multifunctional T cells. However, BK61-specific CD4 T cells showed weak secondary response upon challenge with PRV DX strain. Further vaccination with PRV-infected dendritic cells (DCs) transiently increased the percentage of IFN-γ-positive CD4 and CD8 T cells but eventually restored to low frequency and did not improve the protective efficacy of BK61 against challenge, suggesting that PRV BK61 induced a relatively weak cellular immunity that could not be overcome by the DC vaccination. Similar immune responses were also observed following vaccination with another PRV LAV HD/c in mice and pigs, suggesting that this may be an intrinsic drawback of PRV LAVs in inducing cellular immunity. Our results demonstrated that PRV LAVs elicited a CD4 Th1-biased weak cellular immunity which is implicative for the development of PRV-vectored vaccine.
伪狂犬病病毒（PRV）可引起猪的奥耶斯基氏病，对中国养猪业具有重要经济影响，甚至对公共卫生构成威胁。尽管该疾病已通过接种PRV减毒活疫苗（LAVs）得到控制，但PRV LAVs诱导细胞免疫的效力尚未得到充分表征。在本研究中，我们以最常用的PRV LAVs——PRV巴塔K61株（BK61）为模型，通过多色流式细胞术重新检测了BK61在小鼠和猪体内引发的细胞免疫反应。我们发现，接种疫苗后几乎未检测到T细胞、NK细胞和B细胞的表型激活。然而，在用活的BK61病毒再次刺激后，主要检测到的是产生抗原特异性IFN-γ的CD4 T细胞而非CD8 T细胞，但其频率较低。这些BK61特异性CD4 T细胞也能够同时产生TNF-α和IL-2，显示出多功能T细胞的特征。然而，BK61特异性CD4 T细胞在用PRV DX株攻击时表现出较弱的二次反应。用PRV感染的树突状细胞（DCs）进一步接种可短暂增加IFN-γ阳性CD4和CD8 T细胞的百分比，但最终恢复到低频，且并未提高BK61对攻击的保护效力，这表明PRV BK61诱导的细胞免疫相对较弱，无法通过DC接种来克服。在用另一种PRV LAV HD/c对小鼠和猪进行接种后也观察到了类似的免疫反应，这表明这可能是PRV LAVs在诱导细胞免疫方面的固有缺陷。我们的结果表明，PRV LAVs引发了以CD4 Th1为主的弱细胞免疫，这对PRV载体疫苗的开发具有启示意义。
