Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA.
PLoS Pathog. 2011 Sep;7(9):e1002220. doi: 10.1371/journal.ppat.1002220. Epub 2011 Sep 8.
Human gammaherpesviruses are associated with the development of lymphoproliferative diseases and B cell lymphomas, particularly in immunosuppressed hosts. Understanding the molecular mechanisms by which human gammaherpesviruses cause disease is hampered by the lack of convenient small animal models to study them. However, infection of laboratory strains of mice with the rodent virus murine gammaherpesvirus 68 (MHV68) has been useful in gaining insights into how gammaherpesviruses contribute to the genesis and progression of lymphoproliferative lesions. In this report we make the novel observation that MHV68 infection of murine day 15 fetal liver cells results in their immortalization and differentiation into B plasmablasts that can be propagated indefinitely in vitro, and can establish metastasizing lymphomas in mice lacking normal immune competence. The phenotype of the MHV68 immortalized B cell lines is similar to that observed in lymphomas caused by KSHV and resembles the favored phenotype observed during MHV68 infection in vivo. All established cell lines maintained the MHV68 genome, with limited viral gene expression and little or no detectable virus production - although virus reactivation could be induced upon crosslinking surface Ig. Notably, transcription of the genes encoding the MHV68 viral cyclin D homolog (v-cyclin) and the homolog of the KSHV latency-associated nuclear antigen (LANA), both of which are conserved among characterized γ2-herpesviruses, could consistently be detected in the established B cell lines. Furthermore, we show that the v-cyclin and LANA homologs are required for MHV68 immortalization of murine B cells. In contrast the M2 gene, which is unique to MHV68 and plays a role in latency and virus reactivation in vivo, was dispensable for B cell immortalization. This new model of gammaherpesvirus-driven B cell immortalization and differentiation in a small animal model establishes an experimental system for detailed investigation of the role of gammaherpesvirus gene products and host responses in the genesis and progression of gammaherpesvirus-associated lymphomas, and presents a convenient system to evaluate therapeutic modalities.
人类γ疱疹病毒与淋巴组织增生性疾病和 B 细胞淋巴瘤的发展有关，特别是在免疫抑制宿主中。由于缺乏方便的小动物模型来研究这些病毒，因此了解人类γ疱疹病毒引起疾病的分子机制受到了阻碍。然而，用啮齿动物γ疱疹病毒鼠γ疱疹病毒 68（MHV68）感染实验室品系的小鼠，对于深入了解γ疱疹病毒如何促进淋巴组织增生性病变的发生和进展非常有用。在本报告中，我们观察到一个新的现象，即 MHV68 感染小鼠 15 日龄胎肝细胞会导致其永生化，并分化为 B 浆母细胞，这些细胞可以在体外无限期地增殖，并在缺乏正常免疫能力的小鼠中建立转移性淋巴瘤。MHV68 永生化 B 细胞系的表型与 KSHV 引起的淋巴瘤相似，类似于体内 MHV68 感染中观察到的优势表型。所有建立的细胞系都保持了 MHV68 基因组，病毒基因表达有限，几乎或根本检测不到病毒产生 - 尽管在表面 Ig 交联后可以诱导病毒重新激活。值得注意的是，在已建立的 B 细胞系中，可以持续检测到编码 MHV68 病毒 cyclin D 同源物（v-cyclin）和 KSHV 潜伏相关核抗原（LANA）同源物的基因的转录，这些基因在已鉴定的γ2-疱疹病毒中都保守。此外，我们还表明，v-cyclin 和 LANA 同源物对于 MHV68 对小鼠 B 细胞的永生化是必需的。相比之下，MHV68 特有的 M2 基因在体内潜伏和病毒重新激活中发挥作用，对于 B 细胞永生化是可有可无的。这种在小动物模型中γ疱疹病毒驱动的 B 细胞永生化和分化的新模型建立了一个实验系统，用于详细研究γ疱疹病毒基因产物和宿主反应在γ疱疹病毒相关淋巴瘤的发生和进展中的作用，并提供了一个方便的系统来评估治疗方法。
