Genes encoded by Major Histocompatibility Complex (MHC) are highly polymorphic, contributing significantly to vertebrate immune response. In this report, MHC locus encoded DQA and DQB genes have been characterized in buffalo (Bubalus bubalis), a livestock species of highest commercial importance in the Indian subcontinent. Full-length sequencing of buffalo DQA1, DQA2 revealed a single open reading frame (ORF) of 768, encoding 256 amino acids while DQB gene locus was 774 nucleotides long, encoding a polypeptide of 258 amino acids. Sequence characterization also helped in documentation of expression of third locus DQA3, first time in buffalo. Expression of MHC Class II genes was evaluated across peripheral blood mononuclear cells (PBMCs) of mastitis affected and non-affected (healthy) Murrah buffaloes as well as after in-vitro challenging of PBMCs of animals of both the groups with Gram-negative bacterial ligand, lipopolysaccharide. SYBRGreen dye based real-time PCR assay using RNA purified and reverse transcribed from PBMCs, indicated more than two fold higher basal expression of DQA (2.3) and DRA (2.3) genes in non-mastitis buffaloes compared to mastitis. Further, melt-curve analysis by assessing shift of peak helped in identification of diverged alleles confirmed to be arising through gene duplication. There was significant difference in the expression of DQA and DQB molecules in PBMCs of mastitis and non-mastitis groups examined after in-vitro LPS challenge. Further, it was also established that duplicated DQ loci might have an effect on lower mastitis occurrence in buffaloes, as observed through association studies. PBMCs, thus, exhibited a unique ability to regulate surface expression of MHC class II molecules during mastitis in buffalo and will be helpful in better understanding the role of these molecules in mastitis occurrence and possible resistance in bovines. Real-time PCR assay could also help in identification of allelic diversity as well as duplication among MHC genes. This is the first report on MHC Class II genes' expression and association with disease resistance in buffalo. Key words: Bubalus bubalis, sequencing, expression, real-time PCR, mastitis

Shailendra Kumar Mishra, Saket Kumar Niranjan, Bhaswati Banerjee, Ranjit Singh Kataria

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Electronic Poster Session - Biology - Disease Resistance 1, , 465, 2018
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