PrP Gene Polymorphisms Research Articles

Abnormalities in Brainstem Auditory Evoked Potentials in Sheep with Transmissible Spongiform Encephalopathies and Lack of a Clear Pathological Relationship.

Scrapie is transmissible spongiform encephalopathy (TSE), which causes neurological signs in sheep, but confirmatory diagnosis is usually made postmortem on examination of the brain for TSE-associated markers like vacuolar changes and disease-associated prion protein (PrPSc). The objective of this study was to evaluate whether testing of brainstem auditory evoked potentials (BAEPs) at two different sound levels could aid in the clinical diagnosis of TSEs in sheep naturally or experimentally infected with different TSE strains [classical and atypical scrapie and bovine spongiform encephalopathy (BSE)] and whether any BAEP abnormalities were associated with TSE-associated markers in the auditory pathways. BAEPs were recorded from 141 clinically healthy sheep of different breeds and ages that tested negative for TSEs on postmortem tests to establish a reference range and to allow comparison with 30 sheep clinically affected or exposed to classical scrapie (CS) without disease confirmation (test group 1) and 182 clinically affected sheep with disease confirmation (test group 2). Abnormal BAEPs were found in 7 sheep (23%) of group 1 and 42 sheep (23%) of group 2. The proportion of sheep with abnormalities did not appear to be influenced by TSE strain or PrPSc gene polymorphisms. When the magnitude of TSE-associated markers in the auditory pathways was compared between a subset of 12 sheep with and 12 sheep without BAEP abnormalities in group 2, no significant differences in the total PrPSc or vacuolation scores in the auditory pathways could be found. However, the data suggested that there was a difference in the PrPSc scores depending on the TSE strain because PrPSc scores were significantly higher in sheep with BAEP abnormalities infected with classical and L-type BSE, but not with CS. The results indicated that BAEPs may be abnormal in sheep infected with TSEs but the test is not specific for TSEs and that neither vacuolation nor PrPSc accumulation appears to be responsible for the clinical abnormalities.

Polymorphism analysis of prion protein gene in 11 Pakistani goat breeds

ABSTRACTThe association between caprine PrP gene polymorphisms and its susceptibility to scrapie has been investigated in current years. As the ORF of the PrP gene is extremely erratic in different breeds of goats, we studied the PrP gene polymorphisms in 80 goats which belong to 11 Pakistani indigenous goat breeds from all provinces of Pakistan. A total of 6 distinct polymorphic sites (one novel) with amino acid substitutions were identified in the PrP gene which includes 126 (A -> G), 304 (G -> T), 379 (A -> G), 414 (C -> T), 428 (A -> G) and 718 (C -> T). The locus c.428 was found highly polymorphic in all breeds as compare to other loci. On the basis of these PrP variants NJ phylogenetic tree was constructed through MEGA6.1 which showed that all goat breeds along with domestic sheep and Mauflon sheep appeared as in one clade and sharing its most recent common ancestors (MRCA) with deer species while Protein analysis has shown that these polymorphisms can lead to varied primary, secondary and tertiary structure of protein. Based on these polymorphic variants, genetic distance, multidimensional scaling plot and principal component analyses revealed the clear picture regarding greater number of substitutions in cattle PrP regions as compared to the small ruminant species. In particular these findings may pinpoint the fundamental control over the scrapie in Capra hircus on genetic basis.

PrP-associated resistance to scrapie in five highly infected goat herds

The PrP gene polymorphisms at codons 142 (I/M), 154 (R/H), 211 (R/Q), 222 (Q/K) and 240 (S/P) and their association with susceptibility to classical scrapie infection were investigated in five French goat herds displaying a high disease prevalence (>10%). On the basis of PrP(Sc) detection in the central nervous system and in various lymphoid tissues, 301 of 1343 goats were found to be scrapie infected. The statistical analyses indicated that while P(240) mutation had no direct impact on scrapie infection risk, the H(154), Q(211) and K(222) mutations were associated with high resistance to scrapie. The M(142) mutated allele was associated with a limited protection level against the disease. These results further reinforce the view that, like in sheep, the control and eradication of classical scrapie through the selection of certain PrP alleles could be envisaged in commercial goat population.

Surgical approach to adrenal ganglioneuroma: Case report and literature review

AbstractScrapie in sheep is an infectious disease with genetic susceptibility playing an important role. The European Union applied genetics to control scrapie in the sheep population. In goats no clear association between PrP genotypes and resistance to scrapie has been demonstrated yet. Beside investigating this further, it is important to know the PrP genotype distribution in goat breeds. Actually, to estimate the frequency of interesting alleles in a population is a necessary preliminary step to understand how feasible it could be to select them. Aim of this work is to analyse the variability of the PrP gene in goat breeds from a Northern and a Southern Italian regions.Blood samples were collected from 300 goats of the four most common goat breeds reared in Piedmont region, belonging to 81 herds, and from 178 goats of 7 breeds from Basilicata, belonging to 19 herds. PrP gene polymorphisms were detected by direct DNA sequencing on both strands of the PCR products.In total, thirteen point mutations were...

Identification of seven haplotypes of the caprine PrP gene at codons 127, 142, 154, 211, 222 and 240 in French Alpine and Saanen breeds and their association with classical scrapie

In sheep, susceptibility to scrapie is mainly influenced by polymorphisms of the PrP gene. In goats, there are to date few data related to scrapie susceptibility association with PrP gene polymorphisms. In this study, we first investigated PrP gene polymorphisms of the French Alpine and Saanen breeds. Based on PrP gene open reading frame sequencing of artificial insemination bucks (n=404), six encoding mutations were identified at codons 127, 142, 154, 211, 222 and 240. However, only seven haplotypes could be detected: four (GIH(154)RQS, GIRQ(211)QS, GIRRK(222)S and GIRRQP(240)) derived from the wild-type allele (G(127)I(142)R(154)R(211)Q(222)S(240)) by a single-codon mutation, and two (S(127)IRRQP(240) and GM(142)RRQP(240)) by a double-codon mutation. A case-control study was then implemented in a highly affected Alpine and Saanen breed herd (90 cases/164 controls). Mutations at codon 142 (I/M), 154 (R/H), 211 (R/Q) and 222 (Q/K) were found to induce a significant degree of protection towards natural scrapie infection. Compared with the baseline homozygote wild-type genotype I(142)R(154)R(211)Q(222)/IRRQ goats, the odds of scrapie cases in IRQ(211)Q/IRRQ and IRRK(222)/IRRQ heterozygous animals were significantly lower [odds ratio (OR)=0.133, P<0.0001; and OR=0.048, P<0.0001, respectively]. The heterozygote M(142)RRQ/IRRQ genotype was only protective (OR=0.243, P=0.0186) in goats also PP(240) homozygous at codon 240. However, mutated allele frequencies in French Alpine and Saanen breeds were low (0.5-18.5 %), which prevent us from assessing the influence of all the possible genotypes in natural exposure conditions.

Polymorphism of goat PrP gene in Northern and Southern Italian breeds

Scrapie in sheep is an infectious disease with genetic susceptibility playing an important role. The European Union applied genetics to control scrapie in the sheep population. In goats no clear association between PrP genotypes and resistance to scrapie has been demonstrated yet. Beside investigating this further, it is important to know the PrP genotype distribution in goat breeds. Actually, to estimate the frequency of interesting alleles in a population is a necessary preliminary step to understand how feasible it could be to select them. Aim of this work is to analyse the variability of the PrP gene in goat breeds from a Northern and a Southern Italian regions.Blood samples were collected from 300 goats of the four most common goat breeds reared in Piedmont region, belonging to 81 herds, and from 178 goats of 7 breeds from Basilicata, belonging to 19 herds. PrP gene polymorphisms were detected by direct DNA sequencing on both strands of the PCR products.In total, thirteen point mutations were identified: G37V, T110P, G127S, M137I, I142M, I142T, H143R, R154H, P168Q, T194P, R211Q, Q222K and S240P (the substitutions I142T and T194P are novel). This variability gave rise to 14 alleles. The allele with S127 mutation and the allele with Q211 mutation were found only in Northern goats while V37, I137, T142, R143 and P194 alleles were detected only in Southern goats.Regarding the alleles that were present in both groups, the M142 allele was statistically associated with Northern goats (χ2=39.84, p-value=<0.001) while K222 and H154 alleles were significantly associated with breeds from the South (χ2=54.75, p-value=<0.001; χ2=5.68, p-value=<0.05, respectively). The substitutions T110P, M137I, I142T, P168Q, and T194P were found at a low rate in both Southern and Northern goats and no statistically significant differences were observed between the groups.The present study revealed a high variability in the caprine PrP gene and clear frequency differences between Northern and Southern breeds, with mutations exclusively or significantly associated with one group or the other. M142 and K222 are known to be related to protection against scrapie in goats. More case-control studies are necessary to confirm the protective role of these variants; in fact if this role is confirmed it will allow the introduction of breeding programme to select for resistance to TSEs also in goats.

Selection of ovine housekeeping genes for normalisation by real-time RT-PCR; analysis of PrPgene expression and genetic susceptibility to scrapie

BackgroundCellular prion protein expression is essential for the development of transmissible spongiform encephalopathies (TSEs), and in sheep, genetic susceptibility to scrapie has been associated to PrP gene polymorphisms. To test the hypothetical linkage between PrP gene expression and genetic susceptibility, PrP mRNA levels were measured by real-time RT-PCR in six ovine tissues of animals with different genotypes.ResultsPrevious to the PrP gene expression analysis the stability of several housekeeping (HK) genes was assessed in order to select the best ones for relative quantification. The normalisation of gene expression was carried out using a minimum of three HK genes in order to detect small expression differences more accurately than using a single control gene. The expression stability analysis of six HK genes showed a large tissue-associated variation reflecting the existence of tissue-specific factors. Thereby, a specific set of HK genes was required for an accurate normalisation of the PrP gene expression within each tissue. Statistical differences in the normalised PrP mRNA levels were found among the tissues, obtaining the highest expression level in obex, followed by ileum, lymph node, spleen, cerebellum and cerebrum. A tendency towards increased PrP mRNA levels and genetic susceptibility was observed in central nervous system. However, the results did not support the hypothesis that PrP mRNA levels vary between genotypes.ConclusionThe results on PrP gene expression presented here provide valuable baseline data for future studies on scrapie pathogenesis. On the other hand, the results on stability data of several HK genes reported in this study could prove very useful in other gene expression studies carried out in these relevant ovine tissues.

PrP genotype in Sarda breed sheep and its relevance to scrapie. Brief report.

Several PrP gene polymorphisms modulate sheep scrapie susceptibility. Recently, an increase of scrapie outbreaks has been reported in Italy. A vaccine containing sheep brain homogenate was used in most of the outbreaks. We investigated PrP gene polymorphisms in scrapie-affected and clinically healthy Sarda breed sheep from a flock exposed to the aforementioned vaccine, and in affected Sarda sheep from unexposed flocks. All affected animals were (Gln/Gln)171 homozygous. Moreover, we observed no variation for Ala136 and a new polymorphism (Lys to Asn) at codon 176. Our findings confirm the correlation between scrapie and (Gln/Gln)171 in breeds with no variation for Ala136.

Transgenic analysis of prion diseases.

Prion diseases are fatal transmissible neurological disorders afflicting a range of mammalian species. Although still controversial, a large body of data suggests that the causative agent may be composed entirely of a small glycoprotein. The brains of infected animals have accumulations of a pathogenic protease-resistant isoform (PrPsc) of a normal host-encoded glycoprotein, PrPc or prion protein. A number of lines of biochemical evidence implicate the disease-specific isoform, PrPsc, as the transmissible agent and genetic analysis has shown tight linkage between PrP gene mutations and polymorphisms and differential susceptibility to prion diseases, Perhaps the strongest evidence for a protein-only model of the agent is that PrP gene-ablated mice are resistant to scrapie and that mice with PrP mutation, corresponding to those found in a human familial prion disease, spontaneously develop a transmissible prion disease. This review describes the critical role that transgenic technology has played in the study of the biology of prion diseases and considers the issues raised by this work.

Natural scrapie in a closed flock of Cheviot sheep occurs only in specific PrP genotypes.

Natural scrapie in a closed flock of South Country Cheviot sheep has resulted in 45 deaths between 1986 and 1995. Of these cases, 35 sheep have been analysed for disease-linked PrP gene polymorphisms and all encode valine at codon 136 on at least one allele with 77% homozygous (VV136) and 23% valine/alanine heterozygotes (VA136). Mean survival time was 907 and 1482 days for VV136 and VA136 scrapie affected animals respectively. VV136 animals were all at great risk of disease if allowed to live long enough. However scrapie occurred only in a specific subgroup of VA136 sheep, survival advantage depending on VA136 animals being heterozygous for other polymorphisms at codons 154 or 171. The flock history has been recorded in great detail since its foundation in 1960 however there was no strong evidence for simple maternal or paternal transmission of disease other than inheritance of PrP genotype.

Transmittable diseases: the lessons from bovine spongiform encephalopathy (BSE)

AbstractBSE was first discovered in November 1986 and by July 1991 about 60 000 cases had been confirmed in Great Britain with a low incidence being reported in Northern Ireland, the Republic of Ireland, Switzerland and France. The origin of the extended common source epidemic appears to have been food containing meat and bone meal which contained the causal agent. Recycling of infected cattle waste was significant in increasing exposure, at least from the time of the first unrecognized clinical appearance of the disease in 1985. Small numbers of five species ofBovidaein British zoos, domestic cats, a puma and a cheetah have also succumbed to a newly described spongiform encephalopathy. It is anticipated that as a result of the imposition of a ruminant food ban in countries affected by BSE new infections from food have ceased and the incidence of BSE will fall to zero provided there is no other source of infection. Effective controls are in place in Great Britain and Northern Ireland to protect animal and public health. These include disease notification, compulsory slaughter of suspect animals and incineration of the carcasses, a ban on the feeding of specified bovine offals from cattle over 6 months of age or protein derived from them to man, or any species of animal or bird, and a ban on the feeding of ruminant protein to ruminant animals. Genetic studies are still in progress but there is no epidemiological evidence supporting breed predisposition and bovine PrP gene polymorphisms have not been linked with disease occurrence. The lessons from BSE include: the need to retain an animal health surveillance system to detect new and emerging diseases; a strong veterinary research base in unconventional agent disease; and a powerful epidemiology discipline with access to computerized data recording systems, analytical and modelling expertise. Major changes to the composition or processing of animal food, particularly that derived from sources which are not natural for the consuming species, should be carefully monitored for safety before being permitted.

Natural scrapie in British sheep: breeds, ages and PrP gene polymorphisms.

One hundred and sixty-seven sheep of 32 breeds and crossbreeds affected by natural scrapie throughout Britain were tested for the presence of restriction fragment length polymorphisms of the PrP gene observed when their DNA was digested with EcoRI or HindIII. These polymorphisms have already been associated with different susceptibilities to experimental scrapie (controlled by alleles of the Sip gene) in a flock of Cheviot sheep. In two studies 86 to 92 per cent of the sheep were found to carry the PrP gene EcoRI fragment e1 which is associated with high susceptibility (or the sA allele of Sip) to experimental scrapie. The PrP gene HindIII genotypes of the natural scrapie sheep were not apparently associated with differences in susceptibility to scrapie. There was no link between the polymorphisms and the age or breed of the affected sheep.