Flebbe-Rehwaldt L M, Wood C, Chandran B
Department of Microbiology, Molecular Genetics and Immunology, The University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
J Virol. 2000 Dec;74(23):11040-54. doi: 10.1128/jvi.74.23.11040-11054.2000.
Several gene fragments of human herpesvirus 6 (HHV-6) have been shown to activate the human immunodeficiency virus (HIV) type 1 long terminal repeat (LTR). An open reading frame (ORF) designated B701 (Y. Geng, B. Chandran, S. F. Josephs, and C. Wood, J. Virol. 66:1564-1570, 1992), found within a 22-kb HHV-6A strain GS [HHV-6A(GS)] genomic fragment and a 3.8-kb SalI subfragment, was shown to activate the HIV LTR. B701, also known as HHV-6 U16, is located in the immediate-early B (IE-B) region of the genome. The sequence of the 3.8-kb genomic fragment of HHV-6A(GS) is nearly identical to the published sequence of HHV-6A strain U1102, with minor differences. The HHV-6A(GS) B701 ORF (U16) was used to screen an HHV-6A(GS) cDNA library, and two different but overlapping cDNAs were identified. These cDNAs represent differently spliced transcripts ending at different polyadenylation signals. The ORFs included in the cDNAs are positionally homologous to the human cytomegalovirus (HCMV) UL36 ORF. The ORF in one cDNA was generated by splicing together in frame ORFs U17 and U16, and the second cDNA included ORFs U16 and U15. A third differentially spliced cDNA (U16+), was identified by 5' rapid amplification of cDNA ends. The predicted protein was identical to the U16 portion of the U17/U16 spliced gene product but did not include the U17 portion. 5'-extension analyses of the mRNAs demonstrated that at least two potential transcription initiation sites were used to express the transcripts encoding U17 and U16 gene products. Single-stranded U16 and U17 gene-specific RNA probes hybridized with at least five RNA species from infected cells and demonstrated that the expression of these transcripts was differentially regulated. The U17/U16 spliced gene products were expressed at IE times after infection, but a multiply spliced gene product encoded by U16 was expressed as a late gene. The U17/U16 and the U16+ gene products transactivated the HIV LTR. Thus, while there are similarities to the HCMV UL36-UL38 gene family, some of the IE-B U17/U16 transcripts are unique to HHV-6.
已证实人类疱疹病毒6型（HHV-6）的几个基因片段可激活人类免疫缺陷病毒1型（HIV-1）的长末端重复序列（LTR）。在一个22kb的HHV-6A株GS [HHV-6A(GS)]基因组片段和一个3.8kb的SalI亚片段中发现的一个名为B701的开放阅读框（ORF）（Y. 耿、B. 钱德兰、S. F. 约瑟夫斯和C. 伍德，《病毒学杂志》66:1564 - 1570，1992），被证明可激活HIV LTR。B701，也称为HHV-6 U16，位于基因组的立即早期B（IE-B）区域。HHV-6A(GS)的3.8kb基因组片段序列与已发表的HHV-6A株U1102序列几乎相同，仅有微小差异。HHV-6A(GS) B701 ORF（U16）用于筛选HHV-6A(GS) cDNA文库，并鉴定出两个不同但重叠的cDNA。这些cDNA代表在不同聚腺苷酸化信号处终止的不同剪接转录本。cDNA中包含的ORF与人类巨细胞病毒（HCMV）UL36 ORF在位置上同源。一个cDNA中的ORF是通过将读框内的ORF U17和U16拼接在一起产生的，第二个cDNA包含ORF U16和U15。通过5' cDNA末端快速扩增鉴定出第三个差异剪接的cDNA（U16+）。预测的蛋白质与U17/U16剪接基因产物的U16部分相同，但不包括U17部分。对mRNA的5'延伸分析表明，至少使用了两个潜在的转录起始位点来表达编码U17和U16基因产物的转录本。单链U16和U17基因特异性RNA探针与感染细胞中的至少五种RNA物种杂交，并表明这些转录本的表达受到差异调节。U17/U16剪接基因产物在感染后的IE期表达，但由U16编码的多重剪接基因产物作为晚期基因表达。U17/U16和U16+基因产物可反式激活HIV LTR。因此，虽然与HCMV UL36 - UL38基因家族有相似之处，但一些IE-B U17/U16转录本是HHV-6特有的。
