Genomic Tools and Models for Investigating the Role of Germline Diversity in Mouse Antibody Repertoire Development

Abstract

Abstract In mouse, the immunoglobulin (IG) loci span several Mb of the genome and contain hundreds of repeated, highly homologous sets of variable (V), diversity (D), and joining (J) genes that recombine in B cells to produce an individual’s expressed Ab repertoire. Similar to what has been reported in humans, recent data has shown significant levels of haplotype variation in the IG loci between commonly used inbred mouse strains, challenging the assumption that the IG loci are conserved across all strains of mice. We are using this intra-strain diversity to develop new models for studying the role of IG germline variation on Ab repertoire dynamics and function, questions that remain difficult to address in outbred human populations and pre-existing animal models. Given the diversity and complexity within the IG loci, the development of effective mouse models first requires the characterization of intra-strain differences and the construction of high-quality reference assemblies for the IG loci in several representative strains. To address this problem, we are using the Pacific Biosciences SMRT sequencing to sequence BAC clones spanning the IGH, IGK, and IGL loci in NOD/ShiLtJ and BALB/cByJ strains. We are also gaining additional insight on intra-strain diversity by profiling the expressed IGM, IGK, and IGL repertoires of 18 commonly used laboratory mouse strains. We have used this data to guide the construction of congenic lines on the C57BL/6 background, carrying divergent IGH or IGK loci from BALB/cByJ or NOD/ShiLtJ, respectively. Together, our data show significant germline diversity in our new IG assemblies, as well as divergent Ab repertoires in common lab mouse strains.