Study On PRNP Gene Polymorphisms And Susceptibility To BSE Of Cattle In Jilin Province

Bovine spongiform encephalopathy (BSE) in cattle is one of the transmissible spongiform encephalopathies (TSEs) that are a group of fatal neurodegenerative diseases including Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker syndrome (GSS), Kuru and fatal familial insomnia (FFI) in humans, scrapie in sheep and goats, chronic wasting disease (CWD) in deer and elk, feline spongiform encephalopathy (FSE) in cats, transmissible mink encephalopathy (TME) in minks. The causative agents of these transmissible spongiform encephalopathies are infectious proteins, the so-called prions according to the widely accepted hypothesis of Prusiner.Red Steppe Cattle and YB cattle are new national cattle breeds. They have a lot of excellent traits and are suitable to the climate of the northeast areas of china. Genetic variation should be taken into account to direct genetic conservation programs. DNA marker technology provides an important role to assess the genetic variation that is necessary for the two groups breeding.To consider relationships between nucleotide polymorphisms of the prion protein (PRNP) gene and susceptibility to bovine spongiform encephalopathy (BSE), we investigated polymorphisms in the open reading frame (ORF) and 2 upper regions of the PRNP gene by PCR-SSCP and I/D methods from 2 Jilin local cattle breeds:52 healthy Red Steppe Cattle (RSC) and 34 healthy YanBian(YB)cattle.In the ORF, there are 2 loci (P2,P3)polymorphisms in the 2 goups,the genotype distribution of loci P2 are in Hardy-Weinberg equilibrium by chi-square test. we found single nucleotide polymorphisms (SNPs) at nucleotide positions 168,234,357,461 and 529.we also find amino acid substitutions at nucleotide positions357:N→K,461:S→N,529:V→M in YB cattle.In the upper region, we examined 2 sites of insertion/deletion(indel) polymorphisms:a 23bp indel in the upper region of exon 1, and a 12bp indel in the putative promoter region of intron 1. A previous report suggests that the 23bp indel polymorphism is associated with susceptibility to BSE, but we did not find a difference in allele frequency between healthy and BSE-affected cattle. Three haplotypes (23bp del 12bp del, 23bp ins 12bp ins, and 23bp del 12bp ins) were identified both in YB and in RSC cattle representing a randomly selected population. However, the presence of an additional haplotype 23bp ins 12bp del with a frequency of 0.023 was observed in the group of YB cattle is much higher than in the group of Red Steppe Cattle.In conclusion,we found more number of PRNP polymorphic sites in the 2 cattle breeds examined in the present study than other breeds .Because there is no BSE-affected annimals tested ,further genetic investigatins using many samples from BSE cattle can be useful for assessment of the risk of BSE in our breeds. The association between promoter polymorphisms within the bovine PRNP gene and susceptibility to BSE has been confirmed in a large sample across multiple breeds from Germany and Switzerland. The deletion alleles at the 23 bp and 12 bp indel polymorphisms confered a higher risk of developing BSE on the breeds studied.The promoter polymorphisms exist in our study ,in can be predicted that YB and in RSC cattle breeds have risk of developing BSE.The present results provide data about variations and distribution of the bovine PRNP gene, Investigations have also been launched to determine the relationship between the polymorphism of the PRNP gene and variation within biological and production traits in cattle.