Loparev V N, Parsons J M, Knight J C, Panus J F, Ray C A, Buller R M, Pickup D J, Esposito J J
Poxvirus Section, Viral Exanthems and Herpesvirus Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Proc Natl Acad Sci U S A. 1998 Mar 31;95(7):3786-91. doi: 10.1073/pnas.95.7.3786.
Cowpox virus Brighton red strain (CPV) contains a gene, crmD, which encodes a 320-aa tumor necrosis factor receptor (TNFR) of 44% and 22% identity, respectively, to the CPV TNFR-like proteins, cytokine response modifiers (crm) CrmB and CrmC. The crmD gene was interrupted in three other cowpox strains examined and absent in various other orthopoxviruses; however, four strains of ectromelia virus (ECT) examined contained an intact crmD (97% identity to CPV crmD) and lacked cognates of crmB and crmC. The protein, CrmD, contains a transport signal; a 151-aa cysteine-rich region with 21 cysteines that align with human TNFRII ligand-binding region cysteines; and C-terminal region sequences that are highly diverged from cellular TNFR C-terminal region sequences involved in signal transduction. Bacterial maltose-binding proteins containing the CPV or ECT CrmD cysteine-rich region bound TNF and lymphotoxin-alpha (LTalpha) and blocked their in vitro cytolytic activity. Secreted viral CrmD bound TNF and LTalpha and was detectable after the early stage of replication, using nonreducing conditions, as 60- to 70-kDa predominant and 90- to 250-kDa minor disulfide-linked complexes that were able to be reduced to a 46-kDa form and deglycosylated to a 38-kDa protein. Cells infected with CPV produced extremely low amounts of CrmD compared with ECT. Possessing up to three TNFRs, including CrmD, which is secreted as disulfide-linked complexes in varied amounts by CPV and ECT, likely enhances the dynamics of the immune modulating mechanisms of orthopoxviruses.
牛痘病毒布莱顿红株（CPV）含有一个基因crmD，该基因编码一种320个氨基酸的肿瘤坏死因子受体（TNFR），与CPV的TNFR样蛋白、细胞因子反应调节因子（crm）CrmB和CrmC的同源性分别为44%和22%。在检测的其他三种牛痘病毒株中，crmD基因被中断，并且在其他多种正痘病毒中不存在；然而，检测的四株埃可病毒（ECT）含有完整的crmD（与CPV crmD的同源性为97%），并且缺乏crmB和crmC的同源物。CrmD蛋白含有一个转运信号；一个含有21个半胱氨酸的151个氨基酸的富含半胱氨酸区域，这些半胱氨酸与人类TNFRII配体结合区域的半胱氨酸排列一致；以及与参与信号转导的细胞TNFR C末端区域序列高度不同的C末端区域序列。含有CPV或ECT CrmD富含半胱氨酸区域的细菌麦芽糖结合蛋白结合肿瘤坏死因子（TNF）和淋巴毒素-α（LTα），并阻断它们的体外细胞溶解活性。分泌的病毒CrmD结合TNF和LTα，并且在复制早期后，在非还原条件下可检测到，以60至70 kDa的主要形式和90至250 kDa的次要二硫键连接复合物存在，这些复合物能够被还原为46 kDa的形式并去糖基化为38 kDa的蛋白质。与ECT相比，感染CPV产生的CrmD量极低。正痘病毒拥有多达三种TNFR，包括以不同量以二硫键连接复合物形式分泌的CrmD，这可能增强了正痘病毒免疫调节机制的动态变化。
