IGHV and IGHD encoding antibodies with exceptionally long CDR3H are predominant in the bovine neonatal B cells

Abstract

Abstract We sequentially analyzed 18 RNA-seq libraries from three newborn calves as compared to their dams to understand the development of neonatal humoral immunity. A significant shift in neonatal transcriptome occurs within first week of life post-birth. A set of 110 differentially expressed immune-related genes is noted at birth that include complement, MHCII, chemokine receptors, defensins and cytokines etc. As compared to adults, IGKC is expressed at higher levels in the neonates, despite predominant IGLC expression at birth. The IGHM and IGHD transcripts are expressed at birth and IGHM achieves adult levels by day 7. This is followed by IGHA and IGHG transcripts 14–28 days post birth. Interestingly, most 3′ IGHV1S1(BF4E9) gene, known to encode antibodies with exceptionally long CDR3H, is preferentially expressed in neonatal B cells. In parallel, single longest IGHD2(DH2) gene that encodes such an atypical CDR3H is expressed at high levels at birth. It seems that IGHV1S1(BF4E9) gene has an important functional role in the development and expansion of bovine neonatal B-cell repertoire. To conclude, the bovine neonate acquires humoral immunocompetence by four weeks of neonatal life. [Supported by NSERC Canada Discovery Grant]