RESUMEN
Scrapie and bovine spongiform encephalopathy (BSE) are transmissible spongiform encephalopathies (TSE's) affecting sheep and goats. Susceptibility of goats to scrapie is influenced by polymorphisms of the prion protein gene (PRNP) of the host. Five polymorphisms are associated with reduced susceptibility to TSE's. In the study presented here caprine samples from a scrapie eradication program on Cyprus were genotyped and further characterized using BioRad TeSeE rapid test, histological, immunohistochemical and biochemical methods. In total 42 goats from 20 flocks were necropsied from which 25 goats showed a positive result in the rapid test, a spongiform encephalopathy and an accumulation of pathological prion protein (PrPSc) in the obex. PrPSc deposits were demonstrated in the placenta, peripheral nervous and lymphoreticular system. Two animals showed PrPSc-accumulations in peripheral tissues only. By discriminatory immunoblots a scrapie infection could be confirmed for all cases. Nevertheless, slight deviations in the glycosylation pattern might indicate the presence of different scrapie strains. Furthermore scrapie samples from goats in the current study demonstrated less long term resistance to proteinase K than ovine or caprine BSE control samples. Reduced scrapie susceptibility according to the PRNP genotype was demonstrated (Fishers Exact test, p < 0.05) for the goats with at least one polymorphism (p = 0.023) at the six codons examined and in particular for those with polymorphisms at codon 146 (p = 0.016). This work characterizes scrapie in goats having implications for breeding and surveillance strategies.
Asunto(s)
Enfermedades de las Cabras/genética , Enfermedades por Prión/veterinaria , Animales , Chipre/epidemiología , Femenino , Enfermedades de las Cabras/epidemiología , Enfermedades de las Cabras/patología , Cabras/genética , Enfermedades por Prión/epidemiología , Enfermedades por Prión/genética , Enfermedades por Prión/patología , Proteínas Priónicas/metabolismoRESUMEN
In contrast to scrapie in sheep, the genetic basis of susceptibility to scrapie in goats is not well understood. To study the association of prion protein (PrP) alleles with susceptibility to scrapie in goats in Cyprus, the coding sequence of the caprine PrP gene was determined in 717 goats, including 218 scrapie positive animals. Several novel polymorphisms were detected, such as a novel octarepeat variant and a stop codon mutation. Amino acids at codons 146 and 154 were associated with susceptibility to goat scrapie. Animals heterozygous for serine (S) and aspartate (D) at codon 146 were significantly under-represented in scrapie positive animals and no positive animals were found that were homozygous for these amino acids at codon 146. These results might provide the basis for genetic control of scrapie in Cypriot goats.
Asunto(s)
Predisposición Genética a la Enfermedad , Enfermedades de las Cabras/genética , Cabras/genética , Polimorfismo Genético/genética , Priones/genética , Scrapie/genética , Alelos , Aminoácidos/genética , Animales , Estudios de Casos y Controles , Codón/genética , Chipre , Genotipo , Análisis de Secuencia de ADN/veterinariaRESUMEN
Fleas collected from rats during a three-year period (2000-2003) in 51 areas of all provinces of Cyprus were tested by molecular analysis to characterize the prevalence and identity of fleaborne rickettsiae. Rickettsia typhi, the causative agent of murine typhus, was detected in Xenopsylla cheopis (4%) and in Leptopsylla segnis (6.6%). Rickettsia felis was detected in X. cheopis (1%). This is the first report of R. typhi in X. cheopis and L. segnis from rats, in Cyprus, and the first report of R. felis in X. cheopis in Europe. The role of fleas (mainly X. cheopis) was confirmed in the epidemiologic cycle of murine typhus in Cyprus by interrelation of current results with those of previous studies. The geographic distribution of fleas coincided with the geographic distribution of the pathogen they can harbor, which emphasizes the potential risk of flea-transmitted infections in Cyprus.
Asunto(s)
Ratas/parasitología , Rickettsia felis/aislamiento & purificación , Rickettsia typhi/aislamiento & purificación , Siphonaptera/microbiología , Animales , ChipreRESUMEN
In sheep, scrapie susceptibility is so strongly associated with single nucleotide polymorphisms (SNPs) in the gene encoding the prion protein (PrP) that this linkage constitutes the basis for selective breeding strategies directed toward controlling the disease. For goats, in contrast, the association between scrapie susceptibility/resistance and variations in the PrP gene is far weaker, with only a few identified SNPs showing an influence on scrapie susceptibility. A recent survey of PrP genotypes in Cypriot goats, however, revealed the existence of a robust association between polymorphisms at codon 146 of the caprine PrP gene and resistance/susceptibility to natural scrapie. Here we describe here a high-throughput assay, based on homogeneous MassExtend technology coupled with mass spectrometry, for genotyping codon 146 of the caprine PrP gene. Our results demonstrate that this assay exhibits high accuracy, reproducibility, and repeatability, thereby making it suitable for large-scale SNP genotyping, as required for scrapie surveillance programs.
Asunto(s)
Pruebas Genéticas , Cabras/genética , Procedimientos Analíticos en Microchip/veterinaria , Polimorfismo Genético , Priones/genética , Animales , Codón , Chipre , Susceptibilidad a Enfermedades/veterinaria , Genotipo , Enfermedades de las Cabras/genética , Procedimientos Analíticos en Microchip/métodos , Scrapie/genética , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
To discern whether an association exists between specific combinations of polymorphisms of the prion protein (PrP) and natural scrapie in Cyprus goats, 250 goats were examined, including 164 histologically positive cases. Previously reported amino acid polymorphisms were detected at codons 154 (R-->H), 168(P-->Q), 220(Q-->H) and 240 (S-->P) and nucleotide alterations at codons 42 (a-->g) and 138 (c-->t). Additionally, novel amino acid polymorphisms were detected at codons 146 (N-->S or D) and 151 (R-->H) and new "silent" mutations were found at codons 179 (V,g-->t), 181 (D,c-->t) and 219 (T,c-->t). The two novel polymorphisms at codon 146 were found only in the healthy control and scrapie-negative goats. By comparison, none of the scrapie-affected goats encoded these polymorphisms.