Kay-Jackson P C, Goatley L C, Cox L, Miskin J E, Parkhouse R M E, Wienands J, Dixon L K
Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Woking, Surrey GU24 0NF, UK.
Gulbenkian Institute of Science, Oeiras, Portugal.
J Gen Virol. 2004 Jan;85(Pt 1):119-130. doi: 10.1099/vir.0.19435-0.
The predicted extracellular domain of the CD2v protein of African swine fever virus (ASFV) shares significant similarity to that of the CD2 protein in T cells but has a unique cytoplasmic domain of unknown function. Here we have shown that CD2v is expressed as a glycoprotein of approximately 105 kDa in ASFV-infected cells. In the absence of an extracellular ligand, the majority of CD2v appears to localize to perinuclear membrane compartments. Furthermore, we have shown using the yeast two-hybrid system and by direct binding studies that the cytoplasmic tail of CD2v binds to the cytoplasmic adaptor protein SH3P7 (mAbp1, HIP55), which has been reported to be involved in diverse cellular functions such as vesicle transport and signal transduction. A cDNA clone encoding a variant form of SH3P7 could also be identified and was found to be expressed in a wide range of porcine tissues. Deletion mutagenesis identified proline-rich repeats of sequence PPPKPC in the ASFV CD2v protein to be necessary and sufficient for binding to the SH3 domain of SH3P7. In ASFV-infected cells, CD2v and SH3P7 co-localized in areas surrounding the perinuclear virus factories. These areas also stained with an antibody that recognizes a Golgi network protein, indicating that they contained membranes derived from the Golgi network. Our data provide a first molecular basis for the understanding of the immunomodulatory functions of CD2v in ASFV-infected animals.
非洲猪瘟病毒（ASFV）的CD2v蛋白预测的细胞外结构域与T细胞中CD2蛋白的细胞外结构域有显著相似性，但具有一个功能未知的独特胞质结构域。在此，我们证明CD2v在ASFV感染的细胞中表达为一种约105 kDa的糖蛋白。在没有细胞外配体的情况下，大多数CD2v似乎定位于核周膜区室。此外，我们利用酵母双杂交系统并通过直接结合研究表明，CD2v的胞质尾巴与胞质衔接蛋白SH3P7（mAbp1，HIP55）结合，据报道SH3P7参与多种细胞功能，如囊泡运输和信号转导。还鉴定出一个编码SH3P7变体形式的cDNA克隆，发现其在多种猪组织中表达。缺失诱变确定ASFV CD2v蛋白中富含脯氨酸的PPPKPC序列重复对于与SH3P7的SH3结构域结合是必要且充分的。在ASFV感染的细胞中，CD2v和SH3P7在核周病毒工厂周围的区域共定位。这些区域也用识别高尔基体网络蛋白的抗体染色，表明它们含有源自高尔基体网络的膜。我们的数据为理解CD2v在ASFV感染动物中的免疫调节功能提供了首个分子基础。
