Comparative molecular characterisation of myeloid cathelicidins reveals subspecies-level diversification in indigenous livestock.

Innate immune-related genes are shaped by strong selection pressures due to host-pathogen co-evolution, yet the evolutionary trajectory of cathelicidin antimicrobial (AMP) gene is poorly understood. Despite their central role in innate immunity, the extent of sequence diversification of myeloid cathelicidins across livestock subspecies remains unclear. Present study investigated inter-breed and inter-species level sequence variations of myeloid cathelicidin gene in Vechur cattle (Bos taurus indicus), Ankamali pig (Sus scrofa domesticus), Naked neck chicken (Gallus gallus domesticus) and compared them with their counterparts Bos taurus taurus, Large White Yorkshire (Sus scrofa domesticus), and White leghorn (Gallus gallus domesticus). Sequence and phylogenetic analysis revealed limited divergence and variations confined only to the subspecies level. Two Vechur-derived peptides vBMAP-27 (Vechur cattle Bovine Myeloid Antimicrobial Peptide) and vBMAP-28 displayed single amino acid substitutions at its active motif, whereas vBMAP-34, Ankamali pig and Naked neck chicken sequences were highly conserved. Single amino-acid substitutions altered predicted physicochemical properties, suggesting potential functional modulation. Cathelicidin gene evolution demonstrated by purifying selection, highlighting subtle genetic variation within immune-related gene could contribute to adaptive resilience in locally evolved local livestock breeds.