Saito Reiko, Li Danjuan, Suzuki Yasushi, Sato Isamu, Masaki Hironori, Nishimura Hidekazu, Kawashima Takashi, Shirahige Yutaka, Shimomura Chieko, Asoh Norichika, Degawa Satoshi, Ishikawa Hidefumi, Sato Maki, Shobugawa Yugo, Suzuki Hiroshi
Department of Public Health, Niigata University, Graduate School of Medical and Dental Science, Niigata, Japan.
J Med Virol. 2007 Oct;79(10):1569-76. doi: 10.1002/jmv.20946.
Substantial increase in amantadine-resistant influenza A (H3N2) was reported in Asia and North America in 2005. In this study the frequency and genetic characteristics of amantadine-resistant influenza A, circulated in Japan in 2005-2006 season, were investigated. Isolates were tested by amantadine susceptibility test (TCID(50)/0.2 ml method), and sequencing of the M2 gene to identify mutations that confer resistance. Additionally, the hemagglutinin (HA) and neuraminidase (NA) genes of the viruses were examined. In total, 415 influenza A isolates from six prefectures were screened, and 231 (65.3%) of 354 influenza A (H3N2) were amantadine-resistant, with a serine to asparagine (S31N) change in the M2 gene. However, none of 61 A (H1N1) isolates were resistant. In addition, genetic analyses of the HA gene showed all amantadine-resistant viruses clustered in one (named clade N), possessing specific double mutations at 193, serine to phenylalanine (S193F), and at 225, asparatic acid to asparagine (D225N), and sensitive viruses belonged to another group (clade S). The clinical presentations at the clinical visit did not differ between patients shedding clade N virus and those shedding clade S virus. None of the patients had received previous treatment with amantadine. The results indicate an unusually high prevalence and wide circulation of the amantadine-resistance influenza A (H3N2) in Japan in the 2005-2006 season. These strains had the characteristic double mutations in the HA, in addition to the M2 mutation responsive for resistance. Antiviral resistance monitoring should be intensified and maintained for rapid feedback into treatment strategies, and selection of alternative therapeutic agents.
2005年，亚洲和北美报告了对金刚烷胺耐药的甲型流感（H3N2）大幅增加。在本研究中，调查了2005 - 2006年季节在日本流行的对金刚烷胺耐药的甲型流感的频率和基因特征。通过金刚烷胺敏感性试验（TCID(50)/0.2 ml方法）对分离株进行检测，并对M2基因进行测序以鉴定赋予耐药性的突变。此外，还检测了病毒的血凝素（HA）和神经氨酸酶（NA）基因。总共筛选了来自六个县的415株甲型流感分离株，354株甲型流感（H3N2）中有231株（65.3%）对金刚烷胺耐药，M2基因发生了丝氨酸到天冬酰胺（S31N）的变化。然而，61株甲型流感（H1N1）分离株均无耐药性。此外，对HA基因的遗传分析表明，所有对金刚烷胺耐药的病毒聚集在一个分支（命名为N分支），在193位具有特定的双重突变，丝氨酸变为苯丙氨酸（S193F），在225位天冬氨酸变为天冬酰胺（D225N），而敏感病毒属于另一组（S分支）。排出N分支病毒的患者和排出S分支病毒的患者在临床就诊时的临床表现没有差异。所有患者此前均未接受过金刚烷胺治疗。结果表明，2005 - 2006年季节日本对金刚烷胺耐药的甲型流感（H3N2）异常高发且广泛传播。这些毒株除了具有对耐药性起作用的M2突变外，HA中还具有特征性的双重突变。应加强抗病毒耐药性监测并持续进行，以便迅速反馈到治疗策略中，并选择替代治疗药物。
