title: Epstein-Barr virus infection of naïve B cells in vitro frequently selects clones with mutated immunoglobulin genotypes: implications for virus biology.
abstract: Epstein-Barr virus (EBV), a lymphomagenic human herpesvirus, colonises the host through polyclonal B cell-growth-transforming infections yet establishes persistence only in IgD⁺ CD27⁺ non-switched memory (NSM) and IgD⁻ CD27⁺ switched memory (SM) B cells, not in IgD⁺ CD27⁻ naïve (N) cells. How this selectivity is achieved remains poorly understood. Here we show that purified N, NSM and SM cell preparations are equally transformable in vitro to lymphoblastoid cells lines (LCLs) that, despite upregulating the activation-induced cytidine deaminase (AID) enzyme necessary for Ig isotype switching and Ig gene hypermutation, still retain the surface Ig phenotype of their parental cells. However, both N- and NSM-derived lines remain inducible to Ig isotype switching by surrogate T cell signals. More importantly, IgH gene analysis of N cell infections revealed two features quite distinct from parallel mitogen-activated cultures. Firstly, following 4 weeks of EBV-driven polyclonal proliferation, individual clonotypes then become increasingly dominant; secondly, in around 35% cases these clonotypes carry Ig gene mutations which both resemble AID products and, when analysed in prospectively-harvested cultures, appear to have arisen by sequence diversification in vitro. Thus EBV infection per se can drive at least some naïve B cells to acquire Ig memory genotypes; furthermore, such cells are often favoured during an LCL's evolution to monoclonality. Extrapolating to viral infections in vivo, these findings could help to explain how EBV-infected cells become restricted to memory B cell subsets and why EBV-driven lymphoproliferative lesions, in primary infection and/or immunocompromised settings, so frequently involve clones with memory genotypes.
authors.affiliation: School of Cancer Sciences, College of Medicine and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
authors.forename: Emily
authors.initials: E
authors.lastname: Heath
authors.forename: Noelia
authors.initials: N
authors.lastname: Begue-Pastor
authors.forename: Sridhar
authors.initials: S
authors.lastname: Chaganti
authors.forename: Debbie
authors.initials: D
authors.lastname: Croom-Carter
authors.forename: Claire
authors.initials: C
authors.lastname: Shannon-Lowe
authors.forename: Dieter
authors.initials: D
authors.lastname: Kube
authors.forename: Regina
authors.initials: R
authors.lastname: Feederle
authors.forename: Henri-Jacques
authors.initials: HJ
authors.lastname: Delecluse
authors.forename: Alan B
authors.initials: AB
authors.lastname: Rickinson
authors.forename: Andrew I
authors.initials: AI
authors.lastname: Bell
mesh_terms: D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000821:virology*; D002478:Cells, Cultured; D003564:Cytidine Deaminase / Q000096:biosynthesis; D020031:Epstein-Barr Virus Infections / Q000276:immunology; D005803:Genes, Immunoglobulin; D005838:Genotype; D004854:Herpesvirus 4, Human / Q000276:immunology* / Q000472:pathogenicity / Q000502:physiology*; D006801:Humans; D017578:Immunoglobulin Class Switching; D007072:Immunoglobulin D / Q000235:genetics; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007075:Immunoglobulin M / Q000235:genetics; D007156:Immunologic Memory / Q000276:immunology; D009154:Mutation; D027041:Somatic Hypermutation, Immunoglobulin; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000096:biosynthesis
chemical_list: D007072:Immunoglobulin D; D007143:Immunoglobulin Heavy Chains; D007075:Immunoglobulin M; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D003564:Cytidine Deaminase