REGULATION OF SV40 GENE EXPRESSION

猿猴病毒40（SV 40）有两个早期转录单位， 从复制起点附近的区域转录。 的 早期早期（EE）转录单位，其RNA编码一个大的T- 抗原和小T抗原，在术后早期占优势 感染 晚期-早期（LE）转录单位RNA起始 站点位于EE TATA盒的上游， 感染后晚期。 我们已经在体外表征了 SV 40早期-早期（EE）和两种晚期-早期（EE）的翻译效率 早期（LE）RNA。 我们证明了一个或多个 两个潜在的AUG启动子密码子的前导序列中， LE RNA抑制下游T- 此外，LE RNA的翻译 导致新的病毒蛋白质的合成，大小为2.7 Kd。 的 这种蛋白质的作用目前正在研究中。 羧基 T-抗原的末端突变体引起T-抗原的 病毒DNA复制的效率，但在适当的 条件显著降低了感染性病毒的产量 三个数量级的粒子 我们的研究 证明了病毒晚期RNA的减少，部分， 导致CV-1中这些突变体产生的滴度较低， 1 P细胞。 此外，我们已经证明， 感染的CV-1 P细胞中不产生一种蛋白质，即未知蛋白。 C末端突变体 这表明T抗原在 未知蛋白的翻译。

Simian virus 40 (SV40) has two early transcriptional units that are transcribed from a region near the origin of replication. The early-early (EE) transcription unit, whose RNA encodes a large T- antigen and small t-antigen, predominates at early times post infection. The late-early (LE) transcription unit RNA initiation sites are located upstream of the EE TATA box and function at late time post infection. We have characterized the in vitro translational efficiency of SV40 early-early (EE) and two late- early (LE) RNAs. We demonstrated that the presence of one or two potential AUG initiator codons in the leader sequences of the LE RNAs inhibits efficient translation from the downstream T- antigen initiator, AUG. In addition, translation of the LE RNA resulted in the synthesis of new viral proteins, 2.7 Kd in size. The role of this protein is currently under investigation. Carboxy terminal mutants of T-antigen cause a minimal decrease in the efficiency of viral DNA replication but under appropriate conditions significantly decrease the yield of infectious virus particles by three orders of magnitude. Our studies have demonstrated that a reduction in viral late RNA is, in part, responsible for the lower titers produced by these mutants in CV- 1P cells. Furthermore, we have demonstrated that the viral late protein, agnoprotein, is not produced in CV-1P cells infected with C-terminal mutants. This suggest that T-antigen plays a role in the translation of agnoprotein.