Zsak L, Caler E, Lu Z, Kutish G F, Neilan J G, Rock D L
Plum Island Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Greenport, New York 11944-0848, USA.
J Virol. 1998 Feb;72(2):1028-35. doi: 10.1128/JVI.72.2.1028-1035.1998.
Sequence analysis of the right variable genomic region of the pathogenic African swine fever virus (ASFV) isolate E70 revealed a novel gene, UK, that is immediately upstream from the previously described ASFV virulence-associated gene NL-S (L. Zsak, Z. Lu, G. F. Kutish, J. G. Neilan, and D. L. Rock, J. Virol. 70:8865-8871, 1996). UK, transcriptionally oriented toward the right end of the genome, predicts a protein of 96 amino acids with a molecular mass of 10.7 kDa. Searches of genetic databases did not find significant similarity between UK and other known genes. Sequence analysis of the UK genes from several pathogenic ASFVs from Europe, the Caribbean, and Africa demonstrated that this gene was highly conserved among diverse pathogenic isolates, including those from both tick and pig sources. Polyclonal antibodies raised against the UK protein specifically precipitated a 15-kDa protein from ASFV-infected macrophage cell cultures as early as 2 h postinfection. A recombinant UK gene deletion mutant, deltaUK, and its revertant, UK-R, were constructed from the E70 isolate to study gene function. Although deletion of UK did not affect the growth characteristics of the virus in macrophage cell cultures, deltaUK exhibited reduced virulence in infected pigs. While mortality among parental E70- or UK-R-infected animals was 100%, all deltaUK-infected pigs survived infection. Fever responses were comparable in E70-, UK-R-, and deltaUK-infected groups; however, deltaUK-infected animals exhibited significant, 100- to 1,000-fold, reductions in viremia titers. These data indicate that the highly conserved UK gene of ASFV, while being nonessential for growth in macrophages in vitro, is an important viral virulence determinant for domestic pigs.
对致病性非洲猪瘟病毒（ASFV）分离株E70的可变基因组右侧区域进行序列分析，发现了一个新基因UK，它位于先前描述的与ASFV毒力相关的基因NL-S（L. Zsak、Z. Lu、G. F. Kutish、J. G. Neilan和D. L. Rock，《病毒学杂志》70:8865 - 8871，1996年）的上游紧邻位置。UK基因转录方向朝向基因组右端，预测编码一个含96个氨基酸、分子量为10.7 kDa的蛋白质。对遗传数据库的搜索未发现UK与其他已知基因有显著相似性。对来自欧洲、加勒比地区和非洲的几种致病性ASFV的UK基因进行序列分析表明，该基因在不同的致病性分离株中高度保守，包括来自蜱和猪源的分离株。针对UK蛋白制备的多克隆抗体早在感染后2小时就能从ASFV感染的巨噬细胞培养物中特异性沉淀出一种15 kDa的蛋白质。从E70分离株构建了重组UK基因缺失突变体deltaUK及其回复株UK-R，以研究基因功能。虽然缺失UK不影响病毒在巨噬细胞培养物中的生长特性，但deltaUK在感染猪中表现出毒力降低。亲本E70或UK-R感染动物的死亡率为100%，而所有deltaUK感染的猪均存活下来。E70、UK-R和deltaUK感染组的发热反应相当；然而，deltaUK感染的动物病毒血症滴度显著降低，降低了100至1000倍。这些数据表明，ASFV高度保守的UK基因虽然对体外巨噬细胞生长并非必需，但却是家猪重要的病毒毒力决定因素。
