Gammaherpesvirus infected B cells display abnormal repertoire

Abstract

Abstract Gammaherpesviruses (γHV) are oncogenic viruses that establish lifelong latency in B cells. Chronic infection with human γHV, Kaposi’s sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV) is associated with the development of lymphoproliferative diseases, lymphomas and other types of cancer. The murine equivalent of human γHV, MHV68, is widely used as an animal model for γHV infection. Primary infection is associated with mucosal tissue replication, expansion in germinal center (GC) B cells and chronic persistence in host’s memory B cells. The GC compartment undergoes somatic hypermutation (SHM), class switch recombination (CSR) and repertoire selection which generate long lived antibody-secreting plasma cells and memory B cells. It is not clear what impact γHV infection has on B cell differentiation, affinity maturation and clonal proliferation. We isolated and comparatively analyzed the B cell repertoire of infected and non-infected GC cells from individual mice. This was done by sequencing repertoire from both the single cells and GC populations using NGS high-throughput sequencing. We determined the effect of infection on diversity, selection, mutagenesis and expansion of clones within the GC population of a mouse. Our data indicate that repertoire from MHV68 infected B cell are distinct from non-infected GC cells and is characterized by unique clones, repertoire bias and inappropriate expansion of certain clones. Moreover, both B cell populations share CDR3 variants only on minimum level. Thus, our findings demonstrate that viral infection cause a subversion of GC mutagenic and selective processes which result in a skewed repertoire.