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在利用ＰＣＲ方法克隆麻疹病毒Ｌ４株血凝素（ＨＡ）基因的过程中，获得了一个助融合活性丢失的Ｂ号克隆。其氨基酸序列与具有助融合活性的Ａ号克隆相比，有４个位点不同，分别位于９６、１１７、１４８及５４３位。通过基因间部分序列的交换及定点回复突变，获得了相应位点的突变体。对这些突变体的助融合活性研究发现，１１７、１４８及５４３位氨基酸的改变不影响助融合活性，而当９６位脯氨酸定点回复突变为亮氨酸后，Ｂ克隆血凝素蛋白获得了助融合活性。提示ＨＡ蛋白９６位氨基酸是影响助融合活性的一个重要氨基酸。
In the cloning of the hemagglutinin (HA) gene of measles virus L4 strain by PCR, a B clone was obtained which lost the fusion activity. The amino acid sequence differs from that of clone A, which has co-fusogenic activity in four positions, which are located at positions 96, 117, 148 and 543, respectively. Through the partial gene sequence exchange and site-directed mutagenesis, the corresponding site mutants were obtained. A study of the co-fusion activity of these mutants found that changes in amino acids 117, 148 and 543 did not affect co-fusion activity, whereas B clone hemagglutinin protein was obtained after site-directed mutagenesis of the proline at position 96 to leucine Help fusion activity. It is suggested that the amino acid at position 96 of HA protein is an important amino acid that influences the activity of amalgamation.