Restriction of amino acid change in influenza A virus H3HA: Comparison of amino acid changes observed in nature and in vitro
Restriction of amino acid change in influenza A virus H3HA: Comparison of amino acid changes observed in nature and in vitro
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DOI：
10.1128/jvi.77.18.10088-10098.2003
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发表时间：
2003-09-01
影响因子：
5.4
通讯作者：
Nakajima, S
中科院分区：
文献类型：
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作者：
Nakajima, K;Nobusawa, E;Nakajima, S
采用聚合酶链式反应随机突变的方法，将A/Aichi/2/68(H3N2)株的248个单点氨基酸突变为血凝素(HA)蛋白。这些变化根据它们对血液吸附活性的影响被分为积极的或消极的。我们观察到了以下结果。(I)HA1结构域上残存的氨基酸变化不会消除血吸附活性的百分比约为44%。在自然界中，估计约为39.6%。天然分离株和体外突变株之间HA蛋白上残存氨基酸变化的差异可能是由于对前者的免疫压力所致。(Ii)体外突变体中共有26个氨基酸的变化与H3HA1多肽在1968至2000年间发生的主流氨基酸变化相匹配。在这些人中，有25人呈阳性。我们认为，在进化过程中，HA蛋白上的大部分氨基酸变化可能仅限于A/Aichi/2/68的HA阳性的氨基酸。(3)利用阳性突变体构建了HA蛋白的两点氨基酸变化。这些随机结合的两点氨基酸变化不会抑制血液吸附活性。氨基酸的积累变化可能会无序地发生。(4)从参与主流氨基酸变化的氨基酸分析来看，每个抗原点可以进一步划分为较小的抗原点。这些较小的位点之间的氨基酸替换导致了大多数血吸附的负变化。这些间隙位置可能在维持HA蛋白的功能方面发挥重要作用，因此这些位置的氨基酸变化受到限制。
We introduced 248 single-point amino acid changes into hemagglutinin (HA) protein of the A/Aichi/2/68 (H3N2) strain by a PCR random mutation method. These changes were classified as positive or negative according to their effect on hemadsorption activity. We observed following results. (i) The percentage of surviving amino acid changes on the HA1 domain that did not abrogate hemadsorption activity was calculated to be ca. 44%. In nature, it is estimated to be ca. 39.6%. This difference in surviving amino acid changes on the HA protein between natural isolates and in vitro mutants might be due to the immune pressure against the former. (ii) A total of 26 amino acid changes in the in vitro mutants matched those at which mainstream amino acid changes had occurred in the H3HA1 polypeptide from 1968 to 2000. Of these, 25 were positive. We suggest that the majority of amino acid changes on the HA protein during evolution might be restricted to those that were positive on the HA of A/Aichi/2/68. (iii) We constructed two-point amino acid changes on the HA protein by using positive mutants. These two-point amino acid changes with a random combination did not inhibit hemadsorption activity. It is possible that an accumulation of amino acid change might occur without order. (iv) From the analysis of amino acids participating in mainstream amino acid change, each antigenic site could be further divided into smaller sites. The amino acid substitutions in the gaps between these smaller sites resulted in mostly hemadsorption-negative changes. These gap positions may play an important role in maintaining the function of the HA protein, and therefore amino acid changes are restricted at these locations.