While two memory compartments, memory B cells and long-lived plasma cells, are thought to contribute to the successful establishment of memory recall responses, the unique roles of each cellular compartment are still unclear. Herein, by tracing influenza anti-hemagglutinin (HA)-specific antibodies in mice, we demonstrate that pre-existing antibodies secreted by long-lived plasma cells are essential for protection from reinfection with the same influenza virus, whereas protection from secondary infection with an antigenically distinct influenza virus requires memory B-cell activation. These activated memory B cells were largely specific for the conserved HA stem region, and generated sufficient levels of antibodies for protection from heterologous reinfection. Given that the anti-stem plasmablasts derived from the memory B cells were higher affinity than those from naive B cells, our results suggest that maturation of anti-stem memory B cells during primary influenza infection and their subsequent activation are required for protection from reinfection by mutant viruses.

中文翻译：

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防止异源流感病毒再感染需要记忆B细胞激活。

虽然两个记忆区室，即记忆B细胞和长寿浆细胞，被认为有助于成功建立记忆记忆应答，但每个细胞区室的独特作用仍不清楚。本文中，通过追踪小鼠中的抗流感抗血凝素（HA）特异性抗体，我们证明了长寿浆细胞分泌的预先存在的抗体对于防止再次感染相同的流感病毒是必不可少的，而对于防止再次感染流感病毒则至关重要抗原性不同的流感病毒需要记忆B细胞激活。这些活化的记忆B细胞在很大程度上对保守的HA茎区域具有特异性，并产生足够水平的抗体以保护免受异源再感染。