Antigenic and amino acid sequence variation among different clades of H5N1 vaccine candidate viruses.

aHemagglutination inhibition (HI) titers were determined using turkey red blood cells.bTiters for homologous antigen/antisera are shown with values underlined. Titers are presented as the geometric mean titers (GMT) calculated from five independent HI tests.cDifferences among strain-specific cross reactivity are quoted as dilutions relative to that of the end-point dilution value for the homologous antigen/sera response. Viruses are considered antigenically diverse if titers are reported as ≥8-fold difference in two-way tests.dOnly a reassortant virus for Hubei10 was used in assay. Others were wild type viruses.eAmino acid sequence identities were calculated for the 267 residues of the HA1 structural domain (residues 34–300) of the mature HA, using CLUSTALX [84].fSurface residue differences were quantified for the HA1 structural domain (residues 34–300) of the mature HA monomer. For this analysis, 166 of the 267 residues were considered surface residues. The number of surface residue substitutions is given in parentheses.a. 血凝抑制（Hemagglutination inhibition, HI）效价采用火鸡红细胞进行测定。 b. 同源抗原与抗血清的效价以带下划线的数值呈现；所有效价均为五次独立血凝抑制试验计算得到的几何平均效价（geometric mean titers, GMT）。 c. 毒株特异性交叉反应性的差异以相对于同源抗原/血清反应的终点稀释度值的稀释倍数表示；若双向试验中效价差异≥8倍，则判定该病毒具有抗原多样性。 d. 本试验仅使用了一株Hubei10的重配病毒，其余毒株均为野生型病毒。 e. 针对成熟血凝素（hemagglutinin, HA）HA1结构域的267个残基（对应残基位点34–300）的氨基酸序列一致性，通过CLUSTALX [84] 进行计算。 f. 针对成熟血凝素（hemagglutinin, HA）单体的HA1结构域（残基34–300）的表面残基差异开展量化分析；本次分析中，267个残基中有166个被认定为表面残基，表面氨基酸替换的数量标注于括号内。