Polymorphism of 23 bp and 12 bp Insertion/Deletion of the Guanling Cattle Prion Protein Gene and Its Effect on the Resistance to Bovine Spongiform Encephalopathy

Purpose To analyze the polymorphisms of the 23 bp and 12 bp insertion/deletion sites of the prion protein gene (PRNP) in Guanling cattle and their potential role in the resistance to bovine spongiform encephalopathy (BSE).

Methods PCR amplification and sequencing of the PRNP gene 23 bp and 12 bp insertion/deletion sites were performed on 130 Guanling cattle, and the polymorphisms and characteristics of the BSE resistance genes were analyzed.

Results The PRNP 23 bp genotype in Guanling cattle was mainly heterozygous (ID) for insertion (I) and deletion (D), with a frequency of 0.469; while the 12 bp genotype was mainly homozygous insertion (II), with a frequency of 0.600. The allele frequency of the 23 bp insertion was 0.481, and the frequency of the 12 bp insertion was 0.777. Among the haplotypes, I23I12 and D23I12 were the dominant haplotypes, with the frequency of I23I12 reaching 0.457, and that of D23I12 being 0.320, both higher than those in ordinary cattle breeds (Bos taurus), indicating their uniqueness. Among them, the frequency of D23I12 was obviously higher than that of known BSE-susceptible cattle breeds.

Conclusion The 23 bp and 12 bp polymorphisms of PRNP gene in Guanling cattle show a high level of BSE resistance, providing an important reference for the molecular breeding of disease resistance in Chinese local cattle breeds.