Genetic polymorphism of serum lysozyme gene and its association with serum lysozyme activity in indigenous breeds of sheep

Lysozyme acts as an important antimicrobial component in serum and body fluids. Polymorphs of serum lysozyme gene are reported to be significantly associated with disease resistance traits. Therefore, the present study was undertaken to detect polymorphism in serum lysozyme at the genetic level and its association with mean serum lysozyme activity in indigenous breeds of sheep. A total of 275 animals of same sex and season of birth belonging to 3 breeds of indigenous sheep, viz. Chokla, Malpura, and Muzaffarnagri were used in the study. Genomic DNA was extracted from blood samples of the contributing animals and used to amplify 275bp fragment (partial intron 2, exon 3 and partial intron 3) of serum lysozyme gene by polymerase chain reaction. Subsequently, the SSCP study was carried out to identify different allelic patterns and genotypes of the animal included in the study. Seven genotypes AA, AB, AC, AD, AE, AF and DD and consequently 6 alleles namely A, B, C, D,E and F of varied sizes were found in different breeds of sheep. All the 6 alleles were present in Chokla and Malpura whereas only 4 alleles A, C, D and F were present in Muzaffarnagri breed of sheep. As allele was pre dominant in all the 3 breeds of sheep. Nucleotide sequencing of samples showing different genotypic pattern showed differences at nucleotide level between different alleles. Different alleles showed variations at 8 places. Genotypes showed significant (P <= 0.05) associations with mean serum lysozyme activity in Malpura and Muzaffarnagri breed of sheep.