Evolution of Influenza A(H3N2) Viruses in Bhutan for Two Consecutive Years, 2022 and 2023

IF 4.3 4区医学 Q1 INFECTIOUS DISEASES Influenza and Other Respiratory Viruses Pub Date : 2024-10-23 DOI:10.1111/irv.70028

Tshering Dorji, Kunzang Dorji, Sonam Gyeltshen

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Abstract

Background

Influenza A viruses pose a significant public health threat globally and are characterized by rapid evolution of the hemagglutinin (HA) gene causing seasonal epidemics. The aim of this study was to investigate the evolutionary dynamics of A(H3N2) circulating in Bhutan during 2022 and 2023.

Methods

We analysed 166 whole-genome sequences of influenza A(H3N2) from Bhutan, obtained from the GISAID database. We employed a Bayesian Markov Chain Monte Carlo (MCMC) framework, with a curated global dataset of HA sequences from regions with significant migration links to Bhutan. Phylogenetic, temporal, and phylogeographic analyses were conducted to elucidate the evolutionary dynamics and spatial dissemination of the viruses.

Results

Our phylogenetic analysis identified the circulation of influenza A(H3N2) Clade 3C.2a1b.2a.2 in Bhutan during 2022 and 2023, with viruses further classified into three subclades: 2a.3 (39/166), 2a.3a.1 (58/166) and 2a.3b (69/166). The TMRCA estimates suggest that these viral lineages originated approximately 1.93 years prior to their detection. Phylogeographic analysis indicates introductions from the United States in 2022 and Australia in 2023. The mean evolutionary rate across all gene segments was calculated to be 4.42 × 10⁻³ substitutions per site per year (95% HPD: 3.19 × 10⁻³ to 5.84 × 10⁻³), with evidence of purifying selection and limited genetic diversity. Furthermore, reassortment events were rare, with an estimated rate of 0.045 events per lineage per year.

Conclusion

Our findings show that primary forces shaping the local evolution of the influenza A(H3N2) in Bhutan are largely stochastic, with only sporadic instances of adaptive change, and thus underscore the importance of continuous surveillance to mitigate the impact of evolving strains.

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不丹甲型 H3N2 流感病毒在 2022 年和 2023 年连续两年的演变情况。

背景：甲型流感病毒对全球公共卫生构成重大威胁，其特点是血凝素（HA）基因快速进化，导致季节性流行。本研究旨在调查 2022 年和 2023 年期间在不丹流行的甲型 H3N2 的进化动态：我们分析了从 GISAID 数据库中获得的不丹 166 个甲型 H3N2 流感全基因组序列。我们采用了贝叶斯马尔可夫链蒙特卡洛（MCMC）框架，并利用从与不丹有重要移民联系的地区收集的全球 HA 序列数据集。我们进行了系统发生学、时间和系统地理学分析，以阐明病毒的进化动态和空间传播：我们的系统发生学分析确定了甲型 H3N2 流感支系 3C.2a1b.2a.2 在 2022 年和 2023 年期间在不丹的传播情况，病毒进一步分为三个亚支系：2a.3（39/166）、2a.3a.1（58/166）和 2a.3b（69/166）。TMRCA 估计表明，这些病毒系起源于它们被发现之前的大约 1.93 年。系统地理学分析表明，病毒分别于 2022 年和 2023 年从美国和澳大利亚引入。根据计算，所有基因片段的平均进化速率为每年每个位点 4.42 × 10-3 个置换（95% HPD：3.19 × 10-3 至 5.84 × 10-3），有证据表明存在纯化选择和有限的遗传多样性。此外，重配事件也很罕见，估计每年每个品系发生 0.045 次：我们的研究结果表明，不丹甲型 H3N2 流感在当地进化的主要力量主要是随机的，只有零星的适应性变化，因此强调了持续监测以减轻进化毒株影响的重要性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Influenza and Other Respiratory Viruses 医学-病毒学

CiteScore

7.20

自引率

4.50%

发文量

120

审稿时长

6-12 weeks

期刊介绍： Influenza and Other Respiratory Viruses is the official journal of the International Society of Influenza and Other Respiratory Virus Diseases - an independent scientific professional society - dedicated to promoting the prevention, detection, treatment, and control of influenza and other respiratory virus diseases. Influenza and Other Respiratory Viruses is an Open Access journal. Copyright on any research article published by Influenza and Other Respiratory Viruses is retained by the author(s). Authors grant Wiley a license to publish the article and identify itself as the original publisher. Authors also grant any third party the right to use the article freely as long as its integrity is maintained and its original authors, citation details and publisher are identified.