EBV infection is common; more than 90% of adults are seropositive for the virus.  In the context of organ transplantation, EBV-naïve transplant recipients are at increased risk of post-transplant complications in the form of EBV-driven post-transplantation lymphoproliferative disorder (PTLD). The B cell clonal dynamics during acute infections that lead to PTLD, compared to those that lead only to chronic asymptomatic infection in healthy subjects, are not well understood. 

To study the B cell responses to acute EBV infection in healthy subjects, we analysed rearranged immunoglobulin heavy chain (IGH) gene transcripts in 5 young adults diagnosed with acute primary mononucleosis. All heavy chain isotypes and subclasses were amplified from cDNA derived from peripheral B cells isolated at the time of acute infection and longitudinally at 6-week intervals for up to 6 months post-infection. T cell receptor beta (TCRB) chains were also amplified from the same samples. Longitudinal immune receptor repertoires were deep sequenced using Illumina MiSeq 2x300 pair-end reads. Additionally, phage libraries of non-native paired single chain Fvs derived from the IGH at early, mid and late time points from each subject were panned against key EBV antigens.

IGH repertoires for each subject revealed signatures of EBV infection on peripheral B cells, with significant alteration of a subset of IGH expressed as IgD. IGH inferred as EBV-specific by phage display were used to annotate each subject’s repertoire to distinguish between clonal expansions of B cells that express antibodies specific for EBV antigens, from those B cells of other specificities that may be expanded by EBV infection of the B cell itself. In contrast to the dynamic B cell responses over the time course, the TCRB repertoire was found to be relatively stable, and was found to include public clonotypes with inferred EBV-specificity.