Smith G L, Howard S T, Chan Y S
Department of Pathology, University of Cambridge, U.K.
J Gen Virol. 1989 Sep;70 ( Pt 9):2333-43. doi: 10.1099/0022-1317-70-9-2333.
Nucleotide sequencing of a region of the vaccinia virus genome proximal to the right inverted terminal repeat (ITR) identified two open reading frames (ORFs) encoding proteins of 39K and 40K with amino acid homology to each other, to another vaccinia virus gene near the opposite end of the virus genome and to the superfamily of serine proteinase inhibitors (serpins). Serpins have now been found in poxviruses from the genera orthopox (cowpox and vaccinia viruses), leporipox (myxoma virus) and avipox (fowlpox virus). One of the vaccinia virus serpins identified here (B13R) shares 92% amino acid identity with the serpin from cowpox virus and 46% and 19% identity with vaccinia serpins B24R and K2L, respectively. The amino acid sequence of B13R reported here differs at 11 positions from a recently reported sequence and contains an additional three internal residues. The serpin genes near the right ITR are separated by 8 kb of DNA. Both genes contain early transcriptional termination signals just downstream of the ORFs and are transcribed in a rightward direction towards the end of the genome. Analysis of mRNAs from virus-infected cells demonstrated that all three vaccinia virus serpin genes are transcribed early during infection. The amino acid sequences at the active sites of these serpins suggest that they may inhibit serine proteinases of differing biochemical specificities. The possible functions of these genes are discussed.
对痘苗病毒基因组中靠近右侧反向末端重复序列（ITR）的一个区域进行核苷酸测序，鉴定出两个开放阅读框（ORF），它们编码的39K和40K蛋白彼此具有氨基酸同源性，与病毒基因组另一端附近的另一个痘苗病毒基因以及丝氨酸蛋白酶抑制剂（丝氨酸蛋白酶抑制剂超家族，serpins）具有同源性。现在已在正痘病毒属（牛痘病毒和痘苗病毒）、兔痘病毒属（黏液瘤病毒）和禽痘病毒属（禽痘病毒）的痘病毒中发现了丝氨酸蛋白酶抑制剂。这里鉴定出的一种痘苗病毒丝氨酸蛋白酶抑制剂（B13R）与牛痘病毒的丝氨酸蛋白酶抑制剂氨基酸序列一致性为92%，与痘苗病毒的丝氨酸蛋白酶抑制剂B24R和K2L的一致性分别为46%和19%。此处报道的B13R氨基酸序列与最近报道的序列在11个位置上不同，并且还包含另外三个内部残基。靠近右侧ITR的丝氨酸蛋白酶抑制剂基因被8 kb的DNA隔开。这两个基因在ORF下游均含有早期转录终止信号，并朝着基因组末端向右转录。对病毒感染细胞的mRNA分析表明，所有三个痘苗病毒丝氨酸蛋白酶抑制剂基因在感染早期均被转录。这些丝氨酸蛋白酶抑制剂活性位点的氨基酸序列表明，它们可能抑制具有不同生化特异性的丝氨酸蛋白酶。讨论了这些基因的可能功能。
