7型腺病毒疫苗株序列测定及其六邻体特性分析

目的 完成7型腺病毒疫苗株(Ad7v)的全序列测定并阐明其六邻体特征。方法 克隆Ad7v基因组17．5～68．0mu片段，应用Sanger双脱氧法进行DNA序列测定，将编码六邻体蛋白的核苷酸序列输入GenBank数据库中，获得录入号为AF515814。用CLUSTAL.V软件比较Ad7v与其他亚组及同一亚组腺病毒的六邻体蛋白的同源性，分析其抗原性的差异，同时用RasMol2．71软件预测Ad7v六邻体三维结构。结果 AdTv17．5～68．0mu由17596个碱基组成。这段基因r链主要编码晚期基因L1、L2和L3，L链编码E2的一部分。六邻体编码多肽位于L3区，由934个氨基酸残基组成，与其他9个已知的六邻体蛋白序列进行多序列同源性比较，发现Ad7／疫苗株与其他亚组腺病毒的同源性为86．8％(Ad4)～78．5％(Ad5)。在同一亚组中，Ad7疫苗株与Ad3同源性最高，高达95．1％。可变序列主要集中在7个高变区(HVRs)，根据Ad2六邻体三维结构模型预测Ad7六邻体三维结构，发现可变区大部分位于六邻体顶端的I1和I2环中。结论 完成了AdTv的全序列分析，其六邻体序列与Ad5、Ad2等其他亚组病毒有很大差异，这一结果为构建新型腺病毒载体打下了基础。

Sequencing of adenovirus type 7 vaccine strain fragment and characterization of the hexon enconding gene

OBJECTIVE: To complete the full-length sequencing of the human adenovirus type 7 vaccine strain (Ad7v) for novel vector constructing. METHODS: The Ad7v DNA was digested with SalI and the 17.5-68.0 map unit (mu) fragment was cloned and sequenced. The homology of encoding sequence of Ad7v hexon to those of group A,C,D,E,F and other numbers of group B was accomplished with the software CLUSTAL.V. The three-dimensional structure of the Ad7v hexon was predicted with the RasMo12.71. RESULTS: The fragment contains 17,596 bp, part of E2 and late gene L1, L2 and L3 were encoded by this region. Polypeptide encoded by hexon gene lies in L3 region, which is composed of 934 amino acids. Multiple sequence alignment with the other nine known hexon protein sequences suggested that the variable sequences are mainly concentrated on seven regions, namely hypervariable regions (HVRs). The seven HVRs are related to type-specificity and group-specificity. The three-dimensional structure of the Ad7v hexon revealed that the variable regions are located in the I1 and I2 loops of the molecule mostly on the tower of the hexon. CONCLUSION: The full-length genome sequencing of Ad7v was accomplished at last. Since the deduced amino acid sequence of Ad7v hexon was quite different from other adenoviral vectors such as Ad5 and Ad2, this virus can be potentially used for the construction of novel gene delivery vectors to counterpart the immunity to the vectors widely used at present.