Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, USA.
J Antimicrob Chemother. 2021 Mar 12;76(4):957-960. doi: 10.1093/jac/dkaa527.
Baloxavir marboxil is an antiviral drug that targets the endonuclease activity of the influenza virus polymerase acidic (PA) protein. PA I38T/M/F substitutions reduce its antiviral efficacy.
To understand the effects of the 19 possible amino acid (AA) substitutions at PA 38 on influenza A(H1N1)pdm09 polymerase activity and inhibition by baloxavir acid, the active metabolite of baloxavir marboxil.
Influenza A(H1N1)pdm09 viral polymerase complexes containing all 19 I38X AA substitutions were reconstituted in HEK293T cells in a mini-replicon assay. Polymerase complex activity and baloxavir inhibitory activity were measured in the presence or absence of 50 nM baloxavir acid.
Only three substitutions (R, K, P) reduced polymerase activity to <79% of I38-WT. When compared with the prototypical baloxavir marboxil resistance marker T38, 5 substitutions conferred 10%-35% reductions in baloxavir acid inhibitory activity (M, L, F, Y, C) and 11 substitutions conferred >50% reductions (R, K, S, N, G, W, A, Q, E, D, H), while two substitutions (V, P) maintained baloxavir acid inhibitory activity.
Most PA 38 substitutions permit a functional replication complex retaining some drug resistance in the mini-replicon assay. This study provides a targeted approach for virus rescue and analysis of novel baloxavir marboxil reduced-susceptibility markers, supports the consideration of a broader range of these markers during antiviral surveillance and adds to the growing knowledge of baloxavir marboxil resistance profiles.
巴洛沙韦是一种靶向流感病毒聚合酶酸性（PA）蛋白内切酶活性的抗病毒药物。PA I38T/M/F 取代会降低其抗病毒功效。
了解 PA 38 上 19 种可能的氨基酸（AA）取代对流感 A(H1N1)pdm09 聚合酶活性以及巴洛沙韦酸（巴洛沙韦马博昔利的活性代谢物）抑制作用的影响。
在迷你复制子测定中，在 HEK293T 细胞中重新构建了包含所有 19 种 I38X AA 取代的流感 A(H1N1)pdm09 病毒聚合酶复合物。在存在或不存在 50nM 巴洛沙韦酸的情况下，测量聚合酶复合物活性和巴洛沙韦的抑制活性。
只有 3 种取代（R、K、P）将聚合酶活性降低至 I38-WT 的<79%。与典型的巴洛沙韦马博昔利耐药标志物 T38 相比，5 种取代导致巴洛沙韦酸抑制活性降低 10%-35%（M、L、F、Y、C），11 种取代导致抑制活性降低>50%（R、K、S、N、G、W、A、Q、E、D、H），而 2 种取代（V、P）保持了巴洛沙韦酸抑制活性。
PA 38 的大多数取代都允许功能性复制复合物在迷你复制子测定中保留一定的耐药性。本研究为病毒拯救和分析新型巴洛沙韦马博昔利低敏感性标志物提供了一种有针对性的方法，支持在抗病毒监测期间考虑更广泛的这些标志物，并为巴洛沙韦马博昔利耐药谱的知识增长做出了贡献。
