Breed predisposition for BSE: epidemiological evidence in Bavarian cattle

Bovine spongiform encephalopathy associated insertion/deletion polymorphisms of the prion protein gene in the four beef cattle breeds from North China

Two insertion/deletion (indel) polymorphisms of the prion protein gene (PRNP), a 23-bp indel in the putative promoter region and a 12-bp indel within intron I, are associated with the susceptibility to bovine spongiform encephalopathy (BSE) in cattle. In the present study, the polymorphism frequencies of the two indels in four main beef cattle breeds (Hereford, Simmental, Black Angus, and Mongolian) from North China were studied. The results showed that the frequencies of deletion genotypes and alleles of 23- and 12-bp indels were lower, whereas the frequencies of insertion genotypes and alleles of the two indels were higher in Mongolian cattle than in the other three cattle breeds. In Mongolian cattle, the 23-bp insertion / 12-bp insertion was the major haplotype, whereas in Hereford, Simmental, and Black Angus cattle, the 23-bp deletion / 12-bp deletion was the major haplotype. These results demonstrated that Mongolian cattle could be more resistant to BSE, compared with the other three cattle breeds, because of its relatively low frequencies of deletion genotypes and alleles of 23- and 12-bp indel polymorphisms. Thus, this race could be important for selective breeding to improve resistance against BSE in this area.

Molecular analysis of carbohydrate N-acetylgalactosamine 4-O sulfotransferase 8 (CHST8) as a candidate gene for bovine spongiform encephalopathy susceptibility

Endogenous prion proteins (PrP) play the central role in the pathogenesis of transmissible spongiform encephalopathies. The carbohydrate N-acetylgalactosamine 4-O sulfotransferase 8 (CHST8) promotes the conversion of the cellular PrP(C) into the pathogenic PrP(d). Six sequence variants within the CHST8 gene were identified by comparative sequencing and genotyped for a sample of 623 animals comprising bovine spongiform encephalopathy (BSE)-affected and healthy control cows representing German Fleckvieh (German Simmental), German Holstein (Holstein-Friesian) and Brown Swiss. Significant differences in the allele, genotype and haplotype frequencies between BSE-affected and healthy cows indicate an association of sequence variant g.37254017G>T with the development of the disease in Brown Swiss cattle.

On the track of the white tiger: pigmentation could be linked to prion diseases, and location explains why

Certain rodent pigmentation mutants spontaneously develop brain spongiform changes. It is hypothesized that animals, and possibly humans, characterized by certain pigmentation gene variants could be more susceptible to prion diseases, which are characterized by this type of neuropathology. This hypothesis could be explained by the common location of the prion protein and several important pigmentation genes in the same chromosome. This common location can promote the joint transfer of both pigmentary and prion protein genes to the progeny. Pigmentation genes could also play a role in regulating protein folding and aggregation. Understanding the relationship between pigmentation genes and prion genes could lead to identify pigmentation variants at higher risk of prion diseases and understand the etiopathogenesis of these still invariably lethal disorders.

Frequencies of polymorphisms associated with BSE resistance differ significantly between Bos taurus, Bos indicus, and composite cattle

Background

Transmissible spongiform encephalopathies (TSEs) are neurodegenerative diseases that affect several mammalian species. At least three factors related to the host prion protein are known to modulate susceptibility or resistance to a TSE: amino acid sequence, atypical number of octapeptide repeats, and expression level. These factors have been extensively studied in breeds of Bos taurus cattle in relation to classical bovine spongiform encephalopathy (BSE). However, little is currently known about these factors in Bos indicus purebred or B. indicus × B. taurus composite cattle. The goal of our study was to establish the frequency of markers associated with enhanced susceptibility or resistance to classical BSE in B. indicus purebred and composite cattle.

Results

No novel or TSE-associated PRNP-encoded amino acid polymorphisms were observed for B. indicus purebred and composite cattle, and all had the typical number of octapeptide repeats. However, differences were observed in the frequencies of the 23-bp and 12-bp insertion/deletion (indel) polymorphisms associated with two bovine PRNP transcription regulatory sites. Compared to B. taurus, B. indicus purebred and composite cattle had a significantly lower frequency of 23-bp insertion alleles and homozygous genotypes. Conversely, B. indicus purebred cattle had a significantly higher frequency of 12-bp insertion alleles and homozygous genotypes in relation to both B. taurus and composite cattle. The origin of these disparities can be attributed to a significantly different haplotype structure within each species.

Conclusion

The frequencies of the 23-bp and 12-bp indels were significantly different between B. indicus and B. taurus cattle. No other known or potential risk factors were detected for the B. indicus purebred and composite cattle. To date, no consensus exists regarding which bovine PRNP indel region is more influential with respect to classical BSE. Should one particular indel region and associated genotypes prove more influential with respect to the incidence of classical BSE, differences regarding overall susceptibility and resistance for B. indicus and B. taurus cattle may be elucidated.

Identification of a heritable polymorphism in bovine PRNP associated with genetic transmissible spongiform encephalopathy: evidence of heritable BSE

Background

Bovine spongiform encephalopathy (BSE) is a transmissible spongiform encephalopathy (TSE) of cattle. Classical BSE is associated with ingestion of BSE-contaminated feedstuffs. H- and L-type BSE, collectively known as atypical BSE, differ from classical BSE by displaying a different disease phenotype and they have not been linked to the consumption of contaminated feed. Interestingly, the 2006 US H-type atypical BSE animal had a polymorphism at codon 211 of the bovine prion gene resulting in a glutamic acid to lysine substitution (E211K). This substitution is analogous a human polymorphism associated with the most prevalent form of heritable TSE in humans, and it is considered to have caused BSE in the 2006 US atypical BSE animal. In order to determine if this amino acid change is a heritable trait in cattle, we sequenced the prion alleles of the only known offspring of this animal, a 2-year-old heifer.

Principal Findings

Sequence analysis revealed that both the 2006 US atypical BSE animal and its 2-year-old heifer were heterozygous at bovine prion gene nucleotides 631 through 633 for GAA (glutamic acid) and AAA (lysine). Both animals carry the E211K polymorphism, indicating that the allele is heritable and may persist within the cattle population.

Conclusions

This is the first evidence that the E211K polymorphism is a germline polymorphism, not a somatic mutation, suggesting BSE may be transmitted genetically in cattle. In the event that E211K proves to result in a genetic form of BSE, this would be the first indication that all 3 etiologic forms of TSEs (spontaneous, hereditary, and infectious) are present in a non-human species. Atypical BSE arising as both genetic and spontaneous disease, in the context of reports that at least some forms of atypical BSE can convert to classical BSE in mice, suggests a cattle origin for classical BSE.

Short communication: Allele, genotype, and haplotype data for bovine spongiform encephalopathy-resistance polymorphisms from healthy US Holstein cattle

Bovine spongiform encephalopathy (BSE) is a neurodegenerative disease of cattle caused by abnormally folded prion proteins. Two regulatory region polymorphisms in the bovine prion gene are associated with resistance to classical BSE disease: a 23-bp region in the promoter that contains a binding site for the repressor protein RP58, and a 12-bp region in intron 1 that has a binding site for the transcription factor SP1. The presence of these binding sites enhances BSE resistance in cattle, whereas cattle that lack these regions are more susceptible to the disease. The present study examined the allele, genotype, and haplotype frequencies for the 23-bp and 12-bp polymorphisms in Holstein cattle from 9 different US states, and these frequencies were compared with data previously established for Holstein cattle from the United Kingdom, Germany, and Japan. Additionally, the coding region of the prion gene was sequenced from the US samples. Finally, archival samples from US Holstein sires born between 1953 and 1957 were analyzed. We found that the resistant allele and genotype frequencies for the US Holstein cattle were as high, or higher, relative to that observed in other countries. Furthermore, the current US frequencies were comparable to those determined in the archival samples from the 1950s. Based on the frequencies of these regulatory region polymorphisms, the US Holstein population is not at a greater risk for BSE than Holsteins worldwide.