PrP polymorphisms in Brazilian sheep

Passos, Daniel Thompsen; Ribeiro, Luiz Alberto Oliveira; Rodrigues, Norma Centeno; Hepp, Diego; Weimer, Tânia A.

doi:10.1016/j.smallrumres.2007.04.008

Cited by 11 publications

(25 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The genotype frequencies we have found were comparable to the ones described by Passos et al (2008) for another herd of Suffolk breed in southern Brazil. They have analyzed polymorphisms in the 136 and 171 codons and found that approximately 49% of the animals (in a herd of 129 sheeps) had the highly susceptible genotype QQ for the 171 codon, whereas we have found 34% of the animals presenting this genotype.…”

Section: Resultssupporting

confidence: 87%

“…The most frequent genotypes found were Q/R and Q/Q, representing 79% of the population (Table 1). Some of the rare genotypes for the Suffolk breed (Q/H and H/H, Passos et al 2008) were also found, but at a reduced frequency as expected (Table 1). The frequency for the genotype R/R, considered wild type for the 171 codon, was only 0.10 (Table 1).…”

Section: Resultssupporting

confidence: 75%

“…Since then, some studies have analyzed variation in codons 136, 154 and 171 of the prion protein (Passos et al 2008, Lima et al 2007, Sotomaior et al 2008), but other codon variations in the PrP gene from Brazilian ovine and goat breeds have not been extensively analyzed.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Single nucleotide polymorphisms at 15 codons of the prion protein gene from a scrapie-affected herd of Suffolk sheep in Brazil

et al. 2011

View full text Add to dashboard Cite

Scrapie is a transmissible spongiform encephalopathy of sheeps and goats, associated with the deposition of a isoform of the prion protein (PrPsc). This isoform presents an altered conformation that leads to aggregation in the host's central nervous and lymphoreticular systems. Predisposition to the prion agent infection can be influenced by specific genotypes related to mutations in amino acids of the PrPsc gene. The most characterized mutations occur at codons 136, 154 and 171, with genotypes VRQ being the most susceptible and ARR the most resistant. In this study we have analyzed polymorphisms in 15 different codons of the PrPsc gene in sheeps from a Suffolk herd from Brazil affected by an outbreak of classical scrapie. Amplicons from the PrPsc gene, encompassing the most relevant altered codons in the protein, were sequenced in order to determine each animal's genotype. We have found polymorphisms at 3 of the 15 analyzed codons (136, 143 and 171). The most variable codon was 171, where all described alleles were identified. A rare polymorphism was found at the 143 codon in 4% of the samples analyzed, which has been described as increasing scrapie resistance in otherwise susceptible animals. No other polymorphisms were detected in the remaining 12 analyzed codons, all of them corresponding to the wild-type prion protein. Regarding the risk degree of developing scrapie, most of the animals (96%) had genotypes corresponding to risk groups 1 to 3 (very low to moderate), with only 4% in the higher risks group. Our data is discussed in relation to preventive measures involving genotyping and positive selection to control the disease.

show abstract

Section: Resultssupporting

confidence: 87%

Section: Resultssupporting

confidence: 75%

See 1 more Smart Citation

Single nucleotide polymorphisms at 15 codons of the prion protein gene from a scrapie-affected herd of Suffolk sheep in Brazil

et al. 2011

View full text Add to dashboard Cite

show abstract

“…Por exemplo, o alelo ARQ é considerado altamente susceptível às EET em geral (inclusive à infecção experimental por EEB); porém, em um isolado em particular, tipo SSBP-1, não se consegue propagá-lo em animais ARQ/ARQ (GOLDMANN et al, 1994 (O´ROURKE et al, 1996;, França (ELSEN et al, 1999), Grã-Bretanha (HUNTER et al, 1997a;1997b;TONGUE et al, 2004;EGLIN et al, 2005) No Brasil, ainda são poucos os trabalhos de genotipagem das raças criadas no país (PASSOS et al, 2008;SOTOMAIOR et al, 2008;ANDRADE et al, 2011) e, principalmente, das raças nativas (LIMA et al, 2007;PACHECO et al, 2007). Ianella et al (2012), no estudo com maior número de genotipagens feitas no país até o momento, analisaram 1400 animais de 13 raças, incluindo várias raças brasileiras como Bergamácia, Crioula, Morada Nova, Rabo Largo, Santa Inês e Somalis Brasileiro.…”

Section: Resistência Genéticaunclassified

“…Alguns trabalhos mostram que existem diferenças nas frequências genotípicas do gene PRNP, quando comparados aos resultados de outros países (SOTOMAIOR, 2007), indicando a necessidade de se ampliar o número de animais genotipados antes que qualquer programa de controle do scrapie seja implantado no Brasil. É essencial, também, que se conheça a estrutura populacional e o grau de variabilidade genética do gene PRNP entre as diferentes raças, como tem sido demonstrado nos primeiros trabalhos brasileiros sobre genotipagem de ovinos (LIMA et al, 2007;PACHECO et al, 2007;PASSOS et al, 2008;SOTOMAIOR et al 2008;ANDRADE et al, 2011;IANELLA et al, 2012).…”

Section: Programas De Controleunclassified

Seleção de ovinos geneticamente resistentes ao scrapie

2012

View full text Add to dashboard Cite

A susceptibilidade dos ovinos ao scrapie está relacionada a polimorfismos do gene da proteína priônica celular (PRNP). Polimorfismos nos códons 136 (alanina, A/ valina, V), 154 (arginina, R/ histidina, H) e 171 (glutamina, Q/ arginina, R/ histidina, H) são os principais determinantes de susceptibilidade/resistência ao scrapie clássico. Eles são combinados em 4 principais variantes do alelo ancestral ARQ: VRQ, AHQ, ARH e ARR. Programas de melhoramento genético na União Europeia e Estados Unidos têm utilizado como estratégia selecionar o alelo resistente ARR, diminuindo a frequência do alelo susceptível VRQ em populações de ovinos. No Brasil, há poucos dados de genotipagem do gene PRNP e, até o momento, nenhum tipo de controle baseado em cruzamentos direcionados foi implementado. Esta revisão focará aspectos importantes como epidemiologia e resistência genética, como ferramenta de programas de controle de scrapie. Palavras-chaves:Genotipagem; Ovinos; Polimorfismo; Proteína priônica celular; Scrapie AbstractSelective breeding for scrapie resistance in sheep. It is well known that the susceptibility of sheep to scrapie is determined by the host's prion protein gene (PRNP). PRNP polymorphisms at codons 136 (alanine, A/ valine, V), 154 (histidine, H/arginine, R) and 171 (glutamine, Q/histidine, H/arginine, R) are the main determinants of sheep susceptibility/resistance to classical scrapie. There are four major variants of the wild-type ARQ allele: VRQ, AHQ, ARH and ARR. Breeding programs have been developed in the European Union and the USA to increase the frequency of the resistant ARR allele while decreasing the frequency of the susceptible VRQ allele in sheep populations. In Brazil, little PRNP genotyping data are available for sheep, and thus far, no controlled breeding scheme for scrapie has been implemented. This review will focus on important epidemiological aspects of scrapie and the use of genetic resistance as a tool in breeding programs to control the disease.

show abstract

Prion protein gene polymorphism in four West African sheep populations

Traoré

Royo

Kaboré

et al. 2012

Trop Anim Health Prod

View full text Add to dashboard Cite

A total of 162 individuals, belonging to three Burkinabé and one Niger sheep populations, were analysed for prion protein (PrP) gene polymorphism at codons 136, 154 and 171. The ARQ allele was the most frequent in both the Burkinabé (86.7%) and the Niger (67.5%) sheep populations. The highly sensitive allele VRQ was not found in the sampled individuals. The highly resistant ARR allele was in very low frequency in the Burkina-Sahel (4.4%) and Mossi (3.2%) populations and was not present in the Djallonké and Touareg populations. Only 4 out of 15 possible PrP genotypes were identified in the sampled individuals. No favourable ARR/ARR genotypes were found in either of the breeds. Sequencing a subgroup of the samples allowed the identification of other five polymorphisms on the PrP gene sequence at codons 116, 138, 151, 237 and 240. The very low frequency of the ARR allele in the West African sheep should dissuade the implementation of a preventive selection programme aimed to increase resistance to scrapie, to avoid an extreme erosion of the genetic stock.

show abstract

PrP polymorphisms in Brazilian sheep

Cited by 11 publications

References 15 publications

Single nucleotide polymorphisms at 15 codons of the prion protein gene from a scrapie-affected herd of Suffolk sheep in Brazil

Single nucleotide polymorphisms at 15 codons of the prion protein gene from a scrapie-affected herd of Suffolk sheep in Brazil

Seleção de ovinos geneticamente resistentes ao scrapie

Prion protein gene polymorphism in four West African sheep populations

Contact Info

Product

Resources

About