Highlights d Slow delivery immunization enhances HIV neutralizing antibody development in monkeys d Slow delivery immunization alters immunodominance of the responding B cells d Weekly longitudinal germinal center (GC) B and T FH analyses provides new GC insights d High-resolution rhesus immunoglobulin locus genomic reference sequence

No abstract

An incomplete ascertainment of genetic variation within the highly polymorphic immunoglobulin heavy chain locus (IGH) has hindered our ability to define genetic factors that influence antibody and B cell mediated processes. To date, methods for locus-wide genotyping of all IGH variant types do not exist. Here, we combine targeted long-read sequencing with a novel bioinformatics tool, IGenotyper, to fully characterize genetic variation within IGH in a haplotype-specific manner. We apply this approach to eight human samples, including a haploid cell line and two mother-father-child trios, and demonstrate the ability to generate high-quality assemblies (>98% complete and >99% accurate), genotypes, and gene annotations, including 2 novel structural variants and 17 novel gene alleles. We show that multiplexing allows for scaling of the approach without impacting data quality, and that our genotype call sets are more accurate than short-read (>35% increase in true positives and >97% decrease in false-positives) and array/imputation-based datasets. This framework establishes a foundation for leveraging IG genomic data to study population-level variation in the antibody response.

The contribution of heritable factors to antibody function and diversity is not fully understood, but has profound implications for delineating variation in the antibody response observed at the population-level. We performed matched long-read-based characterization of the immunoglobulin heavy chain (IGH) locus and expressed antibody repertoire profiling at population-scale to examine, for the first time, the impact of IGH genomic variation on the antibody repertoire. We characterized extensive IGH polymorphism, including novel structural variants (SVs), small insertion/deletions (indels), single nucleotide variants (SNVs), and IG genes and alleles. Countering models that antibody repertoire diversity is driven largely by stochastic processes, we demonstrate that IGH genetic factors make significant contributions to gene usage in both the naive and antigen-experienced repertoire. Specifically, the usage of 73% of IGH genes was associated with common polymorphisms, including those capable of explaining >70% of variance in gene usage. These variants were enriched in transcription factor binding sites and other functional elements associated with V(D)J recombination, and overlapped polymorphisms from genome-wide association studies. Furthermore, we found evidence for the coordinated regulation of IGH genes across the repertoire, demonstrating complex interactions between IGH variants and gene usage. These results refine our understanding of variation observed in the antibody repertoire, and will advance the study of antibody function in disease.

Immunoglobulins (IGs), crucial components of the adaptive immune system, are encoded by three genomic loci. However, the complexity of the IG loci severely limits the effective use of short read sequencing, limiting our knowledge of population diversity in these loci. We leveraged existing long read whole-genome sequencing (WGS) data, fosmid technology, and IG targeted single-molecule, real-time (SMRT) long-read sequencing (IG-Cap) to create haplotype-resolved assemblies of the IG Lambda (IGL) locus from 6 ethnically diverse individuals. In addition, we generated 10 diploid assemblies of IGL from a diverse cohort of individuals utilizing IG-cap. From these 16 individuals, we identi ed signi cant allelic diversity, including 36 novel IGLV alleles. In addition, we observed highly elevated single nucleotide variation (SNV) in IGLV genes relative to IGL intergenic and genomic background SNV density. By comparing SNV calls between our high quality assemblies and existing short read datasets from the same individuals, we show a high propensity for false-positives in the short read datasets. Finally, for the rst time, we nucleotide-resolved common 5-10 Kb duplications in the IGLC region that contain functional IGLJ and IGLC genes. Together these data represent a signi cant advancement in our understanding of genetic variation and population diversity in the IGL locus.

To better understand the subspecies origin of antibody genes in classical inbred mouse strains, the IGH gene loci of four wild-derived mouse strains were explored by analysis of VDJ gene rearrangements. A total of 341 unique IGHV gene sequences were inferred in the wild-derived strains, including 247 sequences that have not previously been reported. The genes of the Non-Obese Diabetic (NOD) strain were also documented, and all but one of the 84 inferred NOD IGHV genes have previously been observed in C57BL/6 mice. This is surprising because the Swiss mouse-derived NOD strain and the C57BL/6 strain have no known shared ancestry. The relationships between the genes of the wild-derived inbred strains and of the C57BL/6, NOD and BALB/c classical inbred strain were then explored. The IGH loci of the C57BL/6 and the MSM/MsJ strains share many sequences, but analysis showed that few sequences are shared with wild-derived strains representing the three major subspecies of the house mouse. There were also few IGHV sequences that were shared by the BALB/c strain and any of the four wild-derived strains. The origins of IGHV genes in the C57BL/6, MSM/MsJ and BALB/c strains therefore remain unclear. These unexpected similarities and differences highlight our lack of understanding of the antibody gene loci of the laboratory mouse, with implications for the interpretation of strain-specific differences in models of antibody-mediated diseases, and of Adaptive Immune Receptor Repertoire sequencing (AIRR-seq) data. These results also suggest that a position-based immunoglobulin gene nomenclature may be unworkable in the mouse.

The genomes of classical inbred mouse strains include genes derived from all three major subspecies of the house mouse, Mus musculus. We recently posited that genetic diversity in the immunoglobulin heavy chain (IGH) gene loci of C57BL/6 and BALB/c mice reflects differences in subspecies origin. To investigate this hypothesis, we conducted high‐throughput sequencing of IGH gene rearrangements to document IGH variable (IGHV), joining (IGHJ) and diversity (IGHD) genes in four inbred wild‐derived mouse strains (CAST/EiJ, LEWES/EiJ, MSM/MsJ and PWD/PhJ) and a single disease model strain (NOD/ShiLtJ), collectively representing genetic backgrounds of several major mouse subspecies. A total of 341 germline IGHV sequences were inferred in the wild‐derived strains, including 247 not curated in the international ImMunoGeneTics information system. By contrast, 83/84 inferred NOD IGHV genes had previously been observed in C57BL/6 mice. Variability among the strains examined was observed for only a single IGHJ gene, involving a description of a novel allele. By contrast, unexpected variation was found in the IGHD gene loci, with four previously unreported IGHD gene sequences being documented. Very few IGHV sequences of C57BL/6 and BALB/c mice were shared with strains representing major subspecies, suggesting that their IGH loci may be complex mosaics of genes of disparate origins. This suggests a similar level of diversity is likely present in the IGH loci of other classical inbred strains. This must now be documented if we are to properly understand interstrain variation in models of antibody‐mediated disease.

Variation in the antibody response has been linked to differential outcomes in disease, and suboptimal vaccine and therapeutic responsiveness, the determinants of which have not been fully elucidated. Countering models that presume antibodies are generated largely by stochastic processes, we demonstrate that polymorphisms within the immunoglobulin heavy chain locus (IGH) impact the naive and antigen-experienced antibody repertoire, indicating that genetics predisposes individuals to mount qualitatively and quantitatively different antibody responses. We pair recently developed long-read genomic sequencing methods with antibody repertoire profiling to comprehensively resolve IGH genetic variation, including novel structural variants, single nucleotide variants, and genes and alleles. We show that IGH germline variants determine the presence and frequency of antibody genes in the expressed repertoire, including those enriched in functional elements linked to V(D)J recombination, and overlapping disease-associated variants. These results illuminate the power of leveraging IGH genetics to better understand the regulation, function, and dynamics of the antibody response in disease.