Schuurman R, Jacobs M, van Strien A, van der Noordaa J, Sol C
Department of Virology, University of Amsterdam, Academic Medical Center, The Netherlands.
J Gen Virol. 1992 Nov;73 ( Pt 11):2879-86. doi: 10.1099/0022-1317-73-11-2879.
The genetic organization of the early region of bovine polyomavirus (BPyV) was studied by analysis of the splice sites used in early mRNA maturation, using reverse transcription-polymerase chain reaction and DNA sequencing techniques. When compared to other polyomaviruses, the BPyV early region appears to have an uncommon organization. In the major early mRNA molecule two small intron sequences of 71 and 77 nucleotides, separated from one another by an 80 nucleotide exon sequence, were identified. Through splicing out both introns, a mRNA molecule is generated that contains an open reading frame with the capacity to encode 619 amino acids. Comparisons with the simian virus 40 large T antigen suggested that this mRNA molecule encodes the BPyV large T antigen. Remarkably, no mRNA product encoding a protein with a size comparable to that of the small t antigens of other polyomaviruses was detected. Another transcript was observed from which only the 77 nucleotide intron sequence had been removed, thereby creating a mRNA molecule with the capacity to encode only 45 amino acids. Whether this mRNA product represents a mature transcript which is translated in BPyV-infected cells or is an intermediate in the formation of the large T mRNA molecule is not known. Analysis of BPyV-specific early mRNA products isolated from BPyV-transformed murine cells revealed only the amplification product representing the putative large T antigen transcript.
通过逆转录-聚合酶链反应和DNA测序技术，对早期mRNA成熟过程中使用的剪接位点进行分析，研究了牛多瘤病毒（BPyV）早期区域的基因组织。与其他多瘤病毒相比，BPyV早期区域的组织形式似乎不常见。在主要的早期mRNA分子中，鉴定出两个小内含子序列，分别为71个和77个核苷酸，它们被一个80个核苷酸的外显子序列隔开。通过剪接去除这两个内含子，产生了一个mRNA分子，该分子包含一个开放阅读框，能够编码619个氨基酸。与猴病毒40大T抗原的比较表明，这个mRNA分子编码BPyV大T抗原。值得注意的是，未检测到编码与其他多瘤病毒小t抗原大小相当的蛋白质的mRNA产物。还观察到另一种转录本，其中仅去除了77个核苷酸的内含子序列，从而产生了一个只能编码45个氨基酸的mRNA分子。尚不清楚该mRNA产物是在BPyV感染细胞中翻译的成熟转录本，还是大T mRNA分子形成过程中的中间体。对从BPyV转化的鼠细胞中分离出的BPyV特异性早期mRNA产物的分析显示，仅扩增出代表推定大T抗原转录本的产物。
