Nakagawa Naoko, Kubota Ritsuko, Nakagawa Toshimasa, Okuno Yoshinobu
Department of Parasitic Agents, Kobe Institute of Health, 4-6, Minatojima-nakamachi, Chuo-ku, Kobe 650-0046, Japan.
Division of Virology, Department of Public Health, Osaka Prefectural Institute of Public Health, 3-69, 1-Chome, Nakamichi, Higashinari-ku, Osaka 537-0025, Japan.
J Gen Virol. 2003 Apr;84(Pt 4):769-773. doi: 10.1099/vir.0.18756-0.
To study the neutralizing epitopes of influenza B virus Yamagata group strains, two monoclonal antibodies (mAbs) were used to select escape mutants of the virus. mAbs 5H4 and 3A12 were found to react with B/Yamagata group strains in haemagglutination inhibition and neutralization tests; no reactivity with B/Victoria group strains was observed. Most of the mutants reacted poorly to polyclonal ferret antibody against the 1998 isolate. Analysis of the deduced amino acid sequences identified a single amino acid substitution at residue 141 (Gly-->Arg) or 149 (Arg-->Gly) in 5H4-escape mutants and 141 (Gly-->Arg), 147 (Thr-->Ile) or 148 (Ser-->Gly) in 3A12-escape mutants. These residues are situated in close proximity in the 'loop' of the haemagglutinin molecule. These epitopes have been conserved in B/Yamagata group strains for almost 10 years in Japan but amino acid substitutions in the loop have been observed in clinical isolates only since 1999.
为研究乙型流感病毒山形系毒株的中和表位，使用两种单克隆抗体（mAb）筛选该病毒的逃逸突变体。在血凝抑制试验和中和试验中发现，单克隆抗体5H4和3A12可与山形系毒株发生反应；未观察到与维多利亚系毒株的反应性。大多数突变体与针对1998年分离株的多克隆雪貂抗体反应较弱。对推导的氨基酸序列进行分析，在5H4逃逸突变体中，第141位残基（甘氨酸→精氨酸）或149位残基（精氨酸→甘氨酸）处有单个氨基酸替换；在3A12逃逸突变体中，第141位残基（甘氨酸→精氨酸）、147位残基（苏氨酸→异亮氨酸）或148位残基（丝氨酸→甘氨酸）处有单个氨基酸替换。这些残基在血凝素分子的“环”中位置相邻。在日本，这些表位在山形系毒株中已保守了近10年，但仅自1999年以来在临床分离株中观察到“环”中的氨基酸替换。
