Characterisation of the immune repertoire of a humanised transgenic mouse through immunophenotyping and high-throughput sequencing

Abstract

Immunoglobulin loci-transgenic animals are widely used in antibody discovery and increasingly in vaccine response modelling. In this study, we phenotypically characterised B-cell populations from the Intelliselect® Transgenic mouse (Kymouse) demonstrating full B-cell development competence. Comparison of the naïve B-cell receptor (BCR) repertoires of Kymice BCRs, naïve human, and murine BCR repertoires revealed key differences in germline gene usage and junctional diversification. These differences result in Kymice having CDRH3 length and diversity intermediate between mice and humans. To compare the structural space explored by CDRH3s in each species’ repertoire, we used computational structure prediction to show that Kymouse naïve BCR repertoires are more human-like than mouse-like in their predicted distribution of CDRH3 shape. Our combined sequence and structural analysis indicates that the naïve Kymouse BCR repertoire is diverse with key similarities to human repertoires, while immunophenotyping confirms that selected naïve B-cells are able to go through complete development.

Biophysical cartography of the native and human-engineered antibody landscapes quantifies the plasticity of antibody developability

“…Interestingly, our findings suggest that the Kymouse (humanized mice) dataset under investigation undersampled the human dataset, both with respect to developability (Figure 7B) and sequence spaces (Supp. Figure 10B), even though lower-level features such as VDJ gene usage and CDR3 length were previously found to overlap (82).…”

Diverse competitor B cell responses to a germline-targeting priming immunogen in human Ig loci transgenic mice

“…It was previously shown that the targeted VRC01-class BCRs are approximately 300 to 900-fold less frequent in this mouse model than in humans 35 , therefore making this model less suitable to test the induction of VRC01-class B cells. In addition, long HCDR3s, which are a requirement for several HIV bnAb classes 52 , have been shown to be less comon in Kymice than in humans 49 , thus complicating testing of bnAb induction in these animals. However, despite differences in the frequencies of specific lineages, the overall BCR repertoire in Kymice mice is comparable to humans 48,49 , therefore making this system suitable to investigate “off-target” B cells.…”

“…In addition, long HCDR3s, which are a requirement for several HIV bnAb classes 52 , have been shown to be less comon in Kymice than in humans 49 , thus complicating testing of bnAb induction in these animals. However, despite differences in the frequencies of specific lineages, the overall BCR repertoire in Kymice mice is comparable to humans 48,49 , therefore making this system suitable to investigate “off-target” B cells.…”

“…We therefore set out to characterize competing B cell responses induced by eOD-GT8 60mers in Intelliselect Transgenic mice (Kymice), transgenic for the complete human Ig loci 48 . Most B cell receptors (BCRs) in Kymice have features similar to those in humans 48 , thus making this an attractive model to predict the most common human antibody responses 49 . A notable exception are VRC01-class precursors, which are substantially less frequent in Kymice than in humans 35,49 .…”

“…Most B cell receptors (BCRs) in Kymice have features similar to those in humans 48 , thus making this an attractive model to predict the most common human antibody responses 49 . A notable exception are VRC01-class precursors, which are substantially less frequent in Kymice than in humans 35,49 . While this makes Kymice non-optimal to investigate VRC01-class responses, they nevertheless present an attractive mouse model to investigate competing B cell responses.…”