Characterization of host adaptation markers among human isolates is important for recognizing the potential for cross-species transmission in avian influenza A viruses. Here, we studied two new potential adaptive mutations, V292I and D740A, in the PB2 protein that were identified by a multi-factor regression model. The study shows that the prevalence of the PB2-V292I mutation is increased in H7N9 influenza viruses isolated from both humans and birds over the past 6 years. The phylogenetic tree showed that influenza A/H7N9 has a lineage based on the strains containing PB2-292I. Polymerase complexes containing PB2-292I/627K derived from H7N9 exhibit increased polymerase activity. PB2-292I coupled with 627K also enhances viral transcription and replication in cells, whereas PB2-292I alone did not show the same effect in the H7N9 virus. However, PB2-740A only had a limited prevalence in 2013, and the change from D to A in PB2-740A may have a negative effect on the replication of the H7N9 virus in cells.

人类分离株中宿主适应标记的表征对于识别甲型禽流感病毒跨物种传播的可能性很重要。在这里，我们研究了 PB2 蛋白中两个新的潜在适应性突变，V292I 和 D740A，这些突变由多因素回归模型确定。该研究表明，在过去 6 年中，从人类和鸟类中分离出的 H7N9 流感病毒中 PB2-V292I 突变的流行率有所增加。系统发育树显示流感 A/H7N9 具有基于包含 PB2-292I 的菌株的谱系。含有源自 H7N9 的 PB2-292I/627K 的聚合酶复合物表现出增加的聚合酶活性。PB2-292I 与 627K 结合也增强了病毒在细胞中的转录和复制，而单独的 PB2-292I 在 H7N9 病毒中没有表现出相同的效果。然而，