Foot-and-mouth disease virus (FMDV) A/ASIA/Sea-97 is a predominant lineage in Southeast Asia and East Asia. However, Sea-97 lineage has not been well studied since its first outbreak in Thailand in 1997. Thus, we conducted phylogenetic and evolutionary analysis of Sea-97 using 224 VP1 sequences of FMDV A/ASIA during 1960 and 2018. Phylogenetic analysis revealed that Sea-97 lineage can be classified into five groups (G1–G5). After the emergence of G2 from G1, the genetic diversity of Sea-97 increased sharply, causing divergence into G3, G4 and G5. During this evolutionary process, Sea-97 lineage, which was initially found only in some countries in Southeast Asia, gradually spread to East Asia. The evolution rate of this lineage was estimated to be 1.2 × 10^–2 substitutions/site/year and there were many differences in amino acid residues compared to vaccine strain. Substitutions at antigenically important sites may affect the efficacy of the vaccine, suggesting the need for appropriate vaccine strains. Our results could provide meaningful information to understand comprehensive characteristic of Sea-97 lineage.

口蹄疫病毒 (FMDV) A/ASIA/Sea-97 是东南亚和东亚的主要谱系。然而，自 1997 年在泰国首次爆发以来，Sea-97 谱系尚未得到很好的研究。因此，我们在 1960 年和 2018 年期间使用 FMDV A/ASIA 的 224 个 VP1 序列对 Sea-97 进行了系统发育和进化分析。系统发育分析显示， Sea-97 谱系可分为五组（G1-G5）。从G1出现G2后，Sea-97的遗传多样性急剧增加，导致分化为G3、G4和G5。在这个进化过程中，最初只在东南亚部分国家发现的Sea-97谱系逐渐向东亚传播。该谱系的进化速率估计为 1.2 × 10 ^–2替换/位点/年，并且与疫苗株相比，氨基酸残基存在许多差异。抗原重要位点的替代可能会影响疫苗的功效，这表明需要适当的疫苗株。我们的结果可以为了解 Sea-97 谱系的综合特征提供有意义的信息。