Profiling of porcine B-cell receptor heavy-chain repertoires indicates the development of a wide public pseudorabies virus-specific immune response after vaccination and challenge.

INTRODUCTION

The antibody repertoire reflects the immune history of an individual. In the present study, we characterized the porcine antibody heavy-chain repertoire following vaccination and challenge with pseudorabies virus (PRV). Due to the limited number and diversity of porcine germline V-genes, we sought to also identify and quantify the public antibody response to different strains that could indicate conserved epitopes.

METHODS

Three groups, each with four specific pathogen-free pigs were vaccinated twice with the Bartha K61 strain and subsequently challenged twice, each group with a different PRV strain. Longitudinal blood sampling was performed before immunization and at multiple time points chosen to coincide with expected peaks of antigen-specific B cell clonal expansion. Bulk heavy-chain repertoire sequencing was carried out and analysed using the Immunoglobulin Multi-species Annotation Tool, and heavy-chain amino acid sequences were clustered. This approach allowed the identification of B-cell receptor (BCR) populations sharing more than 96% identity in their complementary determining regions, suggesting similar pathogen recognition capabilities.

RESULTS

By selecting clusters with frequency kinetics matching immunization or infection events, we identified numerous public clusters shared between pigs within and across groups. Notably, several clusters were detected in more than eight animals, and two clusters were shared by all twelve pigs.

CONCLUSION

Although the selected clusters represent only a subset of the putative PRV-induced repertoire, these findings reveal a striking degree of convergence in the antibody response to PRV in pigs. This work demonstrates that cluster kinetics analysis of bulk BCR sequencing data can identify candidate antigen-specific antibody heavy-chain lineages and provides a framework for future discovery of PRV-specific antibodies.