Regulation Of Effective B Cell Responses To Chronic Infection

Chronic viral infections disrupt B cell responses leading to impaired affinity maturation and delayed control of viremia. Previous studies have identified early pre-germinal center (GC) B cell attrition but the impact of chronic infections on B cell fate decisions in GCs remains poorly understood. To address this question, we used single-cell transcriptional profiling of virus-specific GC B cells during chronic viral infection to test the hypothesis that chronic viral infection disrupted GC B cell fate decisions leading to suboptimal humoral immunity. These studies revealed a critical GC checkpoint disrupted by chronic infection specifically at the point of dark zone re-entry. During chronic viral infection, virus-specific GC B cells were shunted towards terminal plasma cell (PC) or memory B cell (MB) fates at the expense of continued participation in the GC. Early GC exit was associated with decreased B cell mutational burden and antibody quality. Mechanistically, persisting antigen and inflammation independently drove facets of dysregulation, with a key role for inflammation in directing premature terminal differentiation. Thus, these studies define GC defects during chronic viral infection and identify a critical GC checkpoint that is short-circuited, preventing optimal maturation of humoral immunity.