Studies on CD4-2 positive cells a unique T cell subset of fish

利用抗鱼CD_4-1、CD_4-2和CD_8α的单抗，研究了CD_4-2阳性细胞在鱼类适应性免疫中的作用。在2022年财政年度，通过三种体内实验：(A)在鲤鱼疱疹病毒-2(CyHV-2)感染期间；(B)在感染CyHV-2病毒后高温水(HT)处理下；(C)用针对CyHV-2感染的减毒活疫苗免疫。在实验(A)中，我发现在感染CyHV-2后，CD_4-1、CD_4-2和CD_8α阳性淋巴细胞的数量增加，这表明CD_4-2阳性淋巴细胞在抗疱疹病毒感染而不是分枝杆菌感染(在2021财年报道)中发挥了重要作用。对于实验(B)，我意识到在二次α-2攻击后，CD_4-1、CD_4-2和CD_8DNA阳性淋巴细胞的数量迅速增加，这表明二次免疫反应需要CD_4-1和CD_4-2两种阳性淋巴细胞的帮助。对于实验(C)，在随后的强毒攻击后，我注意到在用减毒活疫苗免疫的金布纳中，CD4-2阳性淋巴细胞的数量显著增加，而CD4-1阳性淋巴细胞的数量没有显著变化。这些结果表明，在鱼类中，CD4-2阳性淋巴细胞可能具有不同于CD4-1阳性淋巴细胞的作用。

With the aid of monoclonal antibodies (mAbs) against CD4-1, CD4-2, and CD8α of ginbuna crucian carp (ginbuna), the roles of CD4-2 positive cells in the adaptive immunity of fish were investigated. In fiscal year (FY) 2022, the kinetics of CD4-1, CD4-2, and CD8α positive lymphocytes in ginbuna were studied through three kinds of in vivo experiments: (A) during cyprinid herpesvirus-2 (CyHV-2) infection; (B) under high-temperature water (HT) treatment after CyHV-2 infection; and (C) immunized with a live-attenuated vaccine against CyHV-2 infection. For experiment (A), I found that the number of CD4-1, CD4-2, and CD8α positive lymphocytes increased after CyHV-2 infection, indicating that CD4-2 positive lymphocytes play important roles against herpesvirus infection instead of Mycobacterial infection (reported in FY 2021) in fish. For experiment (B), I realized that the number of CD4-1, CD4-2, and CD8α positive lymphocytes increased rapidly after the secondary CyHV-2 challenge, indicating that the secondary immune responses require the help of both CD4-1 and CD4-2 positive lymphocytes in HT-treated fish. For experiment (C), after subsequent virulent virus challenge, I noticed that the number of CD4-2 positive lymphocytes significantly increased in ginbuna immunized with the live-attenuated vaccine whereas no significant difference was observed in CD4-1 positive lymphocytes. These results suggest that CD4-2 positive lymphocytes can have a different role from CD4-1 positive lymphocytes in fish.