In vivo analysis of human T-cell leukemia virus type 1 reverse transcription accuracy
In vivo analysis of human T-cell leukemia virus type 1 reverse transcription accuracy
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DOI：
10.1128/jvi.74.20.9525-9531.2000
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发表时间：
2000-10-01
影响因子：
5.4
通讯作者：
Mansky, LM
中科院分区：
文献类型：
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作者：
Mansky, LM
一些研究表明，与成人t细胞白血病相关的人类t细胞白血病病毒1型（HTLV-1）的遗传多样性明显低于其他逆转录病毒，包括人类免疫缺陷病毒1型（HIV-1）。为了测试HTLV-1变异是否低于其他逆转录病毒，研究人员开发了一种易于处理的载体系统来测量HTLV-1一轮复制的逆转录准确性。该系统由HTLV-1载体组成，该载体包含一个盒式，带有新霉素磷酸转移酶（neo）基因，DNA复制的细菌起源，以及lacZ α肽基因区域（突变靶标）。载体通过与辅助质粒的反式互补复制。HTLV-1的体内突变率测定为每个复制周期每个靶碱基对7 × 10（-6）个突变。鉴定出的大多数突变是碱基取代突变，即G-to-A和C-to-T转变、移码突变和缺失突变。HTLV-1逆转录酶保守的YMDD基序中蛋氨酸残基突变为丙氨酸或缬氨酸（即M188A或M188V）导致突变率增加2倍，表明该基序在酶的准确性中起作用。HTLV-1的体内突变率与HTLV/BLV逆转录病毒属的另一成员牛白血病病毒（BLV）相当，约为HIV-1的四倍。这些观察结果表明，虽然HTLV-1的突变率明显低于HIV-1，但仅靠较低的突变率并不能解释HTLV-1分离株的低多样性，这支持了HTLV-1在细胞DNA复制过程中主要作为原病毒复制，而不是通过逆转录作为病毒复制的假设。
Several studies have indicated that the genetic diversity of human T-cell leukemia virus type 1 (HTLV-1), a virus associated with adult T-cell Leukemia, is significantly lower than that of other retroviruses, including that of human immunodeficiency virus type 1 (HIV-1), To test whether HTLV-1 variation is lower than other retroviruses, a tractable vector system has been developed to measure reverse transcription accuracy in one round of HTLV-1 replication, This system consists of a HTLV-1 vector that contains a cassette,vith the neomycin phosphotransferase (neo) gene, a bacterial origin of DNA replication, and the lacZ alpha peptide gene region (the mutational target). The vector was replicated by trans-complementation with helper plasmids. The in vivo mutation rate for HTLV-1 was determined to be 7 x 10(-6) mutations per target base pair per replication cycle. The majority of the mutations identified were base substitution mutations, namely, G-to-A and C-to-T transitions, frameshift mutations, and deletion mutations. Mutation of the methionine residue in the conserved YMDD motif of the HTLV-1 reverse transcriptase to either alanine or valine (i.e., M188A or M188V) led to a factor of two increase in the rate of mutation, indicating the role of this motif in enzyme accuracy. The HTLV-1 in vivo mutation rate is comparable to that of bovine leukemia virus (BLV), another member of the HTLV/BLV genus of retroviruses, and is about fourfold tower than that of HIV-1. These observations indicate that while the mutation rate of HTLV-1 is significantly lower than HIV-1, this lower rate alone would not explain the low diversity in HTLV-1 isolates, supporting the hypothesis that HTLV-1 replicates primarily as a provirus during cellular DNA replication rather than as a virus via reverse transcription.