Impact of HCMV-encoded FcγR antagonists on innate immune cell function

巨细胞病毒编码大量的免疫球蛋白，包括Fcγ结合糖蛋白gp34(RL11)、gp68(UL119-118)和gp95(RL12)。我们证明，这些因子都有能力抑制免疫球蛋白介导的效应功能，如触发激活的Fcγ受体FcγRIII/CD16、FcγRII/CD32和FcγRI/CD64，前者通过自然杀伤(NK)细胞执行抗体依赖的细胞毒作用。同时，人巨细胞病毒感染可诱导“适应性”NK细胞的产生和扩增，这在未感染的个体中没有观察到。“适应性”NK细胞不同于传统的NK细胞，发挥着特别有效的抗病毒效应功能，如ADCC。基于我们在分子作用模式以及gp34和gp68如何合作方面的发现，我们现在能够开发新的实验系统，允许依赖于FcγRIII的“适应性”NK细胞在体外进行扩增，并首次展示了gp34和gp68的阻隔潜力。这一方法还使我们能够与P09合作，研究针对gp34和gp68的天然抗体反应在体外和在潜伏感染与体内HCMV疾病的条件下对“适应性”NK细胞增殖的影响。最后，将人巨细胞病毒拮抗剂对Fc-γ-R免疫细胞减弱的假说转移到CD16+γ-Delta T细胞上，并在建立合适的体外培养条件后进行验证。结合冷冻-EM对gp34和gp68超微结构的解析，并应用一组新开发的识别gp34和gp68的单抗，我们设想了基于抗体的干预的新分子概念，可以允许有针对性地调节“适应性”NK和伽马增量T细胞功能。

HCMV encodes a uniquely large arsenal of immunoevasins, including the Fcγ-binding glycoproteins gp34 (RL11), gp68 (UL119-118) and gp95 (RL12). We demonstrated that these factors share the ability to inhibit IgG-mediated effector functions such as triggering of the activating Fcγ receptors FcγRIII/CD16, FcγRII/CD32 and FcγRI/CD64, the former executing antibody-dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells. At the same time, HCMV infection induces the occurrence and expansion of "adaptive" NK cells, which are not observed in uninfected individuals. "Adaptive" NK cells differ from conventional NK cells and exert particularly effective antiviral effector functions, such as ADCC. Based on our findings on the molecular mode of action and how gp34 and gp68 cooperate, we are now in the position to develop new experimental systems, which allow FcγRIII-dependent expansion of “adaptive” NK cells in vitro and demonstrate for the first time the obstructive potential of gp34 and gp68. This approach enables us also to investigate in cooperation with P09 the impact of natural antibody responses against gp34 and gp68 on ”adaptive” NK cell expansion in vitro and under conditions of latent infection vs. HCMV disease in vivo. Finally, the hypothesis of FcγR immune cell attenuation by HCMV antagonists will be transferred to CD16+ gamma delta T cells and tested after the establishment of suitable culture conditions in vitro. In conjunction with the resolution of the gp34 and gp68 ultrastructure via Cryo-EM and applying a panel of newly developed monoclonal antibodies recognizing gp34 and gp68, we envisage new molecular concepts for antibody-based interventions that could allow the targeted modulation of "adaptive" NK as well as gamma deltaT cell functions.