Mapping the HA residues that affect the threshold pH for membrane fusion.

The different amino acids between the HA of Cal/09 and Bris/10 are listed. Single amino acid substitution was introduced into the Cal/09 HA plasmid (-: no change). The threshold pH for fusion was determined by the HA/GFP co-expression fusion assay.本研究逐一列出了Cal/09毒株血凝素（Hemagglutinin，HA）与Bris/10毒株血凝素之间存在差异的氨基酸位点。向Cal/09的HA质粒中引入单氨基酸替换突变（"-"表示未发生氨基酸改变）。通过HA与绿色荧光蛋白（Green Fluorescent Protein，GFP）共表达融合试验，测定了该血凝素介导膜融合的临界pH值。