Impact of the Baloxavir-Resistant Polymerase Acid I38T Substitution on the Fitness of Contemporary Influenza A(H1N1)pdm09 and A(H3N2) Strains
Impact of the Baloxavir-Resistant Polymerase Acid I38T Substitution on the Fitness of Contemporary Influenza A(H1N1)pdm09 and A(H3N2) Strains
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DOI：
10.1093/infdis/jiz418
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发表时间：
2020-01-01
影响因子：
6.4
通讯作者：
Boivin, Guy
中科院分区：
文献类型：
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作者：
Checkmahomed, Liva;M'hamdi, Zeineb;Boivin, Guy
背景：Baloxavir是流感病毒聚合酶酸（PA）蛋白的帽依赖性抑制剂。尽管在病毒学上表现出比奥司他韦更上级，但巴洛沙韦表现出低的耐药屏障。方法：在ST 6 GalI-MDCK细胞和C57/BL 6小鼠中的单一和竞争性感染实验中比较流感A/魁北克/144147/2009（H1 N Opdm 09和A/瑞士/9715293/2013（H3 N2）重组病毒及其I38 T PA突变体。通过病毒产量测定法测定细胞培养上清液和肺匀浆中的病毒滴度。结果：I38 T突变对A（HIN 1）pdm 09和A（H3 N2）病毒的复制动力学无明显影响。在竞争实验中，50%：50%的混合物在单个细胞传代后进化为A（H1N1）病毒的70%：30%（WT/突变体）和A（H3 N2）病毒的88%：12%。I38 T置换在体外传代4代后仍保持稳定。在小鼠中，WT及其I38 T突变体诱导了相似的体重减轻，两种病毒亚型的肺滴度相当。突变体病毒往往占主导地位的WT在小鼠竞争experiments.Conclusion：健身的巴洛沙韦耐I38 T PA突变体出现相对不变的季节性亚型监测其传播。
Background: Baloxavir is a cap-dependent inhibitor of the polymerase acid (PA) protein of influenza viruses. While appearing virologically superior to oseltamivir, baloxavir exhibits a low barrier of resistance. We sought to assess the impact of the common baloxavir-resistant I38T PA substitution on in vitro properties and virulence.Methods: Influenza A/Quebec/144147/2009 (H1N Opdm09 and A/Switzerland/9715293/2013 (H3N2) recombinant viruses and their I38T PA mutants were compared in single and competitive infection experiments in ST6GalI-MDCK cells and C57/BL6 mice. Virus titers in cell culture supernatants and lung homogenates were determined by virus yield assays. Ratios of wild-type (WT) and I38T mutant were assessed by digital RT-PCR.Results: I38T substitution did not alter the replication kinetics of A(HIN1)pdm09 and A(H3N2) viruses. In competition experiments, a 50%:50% mixture evolved to 70%:30% (WT/mutant) for A(H1N1) and 88%:12% for A(H3N2) viruses after a single cell passage. The I38T substitution remained stable after 4 passages in vitro. In mice, the WT and its I38T mutant induced similar weight loss with comparable lung titers in both viral subtypes. The mutant virus tended to predominate over the WT in mouse competition experiments.Conclusion: The fitness of baloxavir-resistant I38T PA mutants appears relatively unaltered in seasonal subtypes warranting surveillance for its dissemination.