The Experts below are selected from a list of 1983 Experts worldwide ranked by ideXlab platform
Lorenzo González - One of the best experts on this subject based on the ideXlab platform.
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Minimum Effective Dose of Cattle and Sheep BSE for Oral Sheep Infection.
PloS one, 2016Co-Authors: Gillian Mcgovern, Stuart Martin, Martin Jeffrey, G. Dexter, S.a.c. Hawkins, Sue J. Bellworthy, L. Thurston, Lynne Algar, Lorenzo GonzálezAbstract:The minimum dose required to cause infection of Romney and Suffolk Sheep of the ARQ/ARQ or ARQ/ARR prion protein gene genotypes following oral inoculation with Romney or Suffolk a Sheep Bovine spongiform encephalopathy (BSE)-derived or cattle BSE-derived agent was investigated using doses ranging from 0.0005g to 5g. ARQ/ARQ Sheep which were methionine (M) / threonine (T) heterozygous or T/T homozygous at codon 112 of the Prnp gene, dosed ARQ/ARR Sheep and undosed controls did not show any evidence of infection. Within groups of susceptible Sheep, the minimum effective oral dose of BSE was found to be 0.05g, with higher attack rates following inoculation with the 5g dose. Surprisingly, this study found no effect of dose on survival time suggesting a possible lack of homogeneity within the inoculum. All clinical BSE cases showed PrPd accumulation in brain; however, following cattle BSE inoculation, LRS involvement within Romney recipients was found to be significantly lower than within the Suffolk Sheep inoculated group which is in agreement with previous reports.
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Factors influencing temporal variation of scrapie incidence within a closed Suffolk Sheep flock
Journal of General Virology, 2012Co-Authors: Lorenzo González, Mark P. Dagleish, Stuart Martin, Jeanie Finlayson, Sílvia Sisó, Samantha L. Eaton, Wilfred Goldmann, Janey Witz, Scott L. Hamilton, Paula StewartAbstract:Several studies have shown that transmission of natural scrapie can occur vertically and horizontally, and that variations in scrapie incidence between and within infected flocks are mostly due to differences in the proportion of Sheep with susceptible and resistant PRNP genotypes. This report presents the results of a 12-year period of scrapie monitoring in a closed flock of Suffolk Sheep, in which only animals of the ARQ/ARQ genotype developed disease. Among a total of 120 of these, scrapie attack rates varied between birth cohorts from 62.5% (5/8) to 100% (9/9), and the incidence of clinical disease among infected Sheep from 88.9% (8/9) to 100% (in five birth cohorts). Susceptible Sheep born to scrapie-infected ewes showed a slightly higher risk of becoming infected (97.2%), produced earlier biopsy-positive results (mean 354 days) and developed disease at a younger age (median 736 days) than those born to non-infected dams (80.3%, 451 and 782 days, respectively). Taken together, this was interpreted as evidence of maternal transmission. However, it was also observed that, for the birth cohorts with the highest incidence of scrapie (90–100%), Sheep born to infected and non-infected dams had a similar risk of developing scrapie (97.1 and 95.3%, respectively). Compared with moderate-attack-rate cohorts (62.5–66.7%), high-incidence cohorts had greater numbers of susceptible lambs born to infected ewes, suggesting that increased rates of horizontal transmission in these cohorts could have been due to high levels of environmental contamination caused by infected placentas.
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Immunological differences between susceptible and resistant Sheep during the preclinical phase of scrapie infection.
Journal of General Virology, 2007Co-Authors: Samantha L. Eaton, Lorenzo González, Mark P. Dagleish, Jeanie Finlayson, Martin Jeffrey, M. Rocchi, S. Hamilton, Jill Sales, Philip Steele, S. M. RodgerAbstract:In order to investigate the relationship between the immune response to scrapie infection and genetic susceptibility to the disease in Sheep, immune cell subsets and prion protein (PrP) expression were determined in susceptible and resistant Suffolk Sheep in the preclinical phase of infection. At 6 months of age, 12 ARQ/ARQ (susceptible) and nine ARR/ARR (resistant) scrapie-free Suffolk lambs were challenged subcutaneously with scrapie inoculum. Prefemoral lymphadenectomies were carried out at 14 and 180 days post-inoculation (p.i.) and serial bleeds were collected at monthly intervals for up to 1 year p.i. An indirect double-labelling procedure was carried out on peripheral blood mononuclear cells (PBMCs) and lymph node cell preparations and analysed using flow cytometry. Prior to scrapie challenge, significantly more PrP+ cells were detected in PBMCs from the susceptible Sheep. Furthermore, following challenge, significantly more CD8+ and γδ + T cells were detected in the PBMCs of the resistant Sheep. However, at both 14 and 180 days p.i, CD21+ cell expression was significantly higher in the lymph node preparations of the susceptible Sheep. In contrast, more CD4+ cells were detected in the lymph nodes of the resistant Sheep at both time points. It was concluded that significant differences in immune cell subsets and PrP expression occur between ARQ/ARQ and ARR/ARR Suffolk Sheep in the preclinical phase of infection.
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Disease-associated PrP in the enteric nervous system of scrapie-affected Suffolk Sheep.
Journal of General Virology, 2003Co-Authors: Ragna Heggebø, Lorenzo González, Charles Mcl. Press, Gjermund Gunnes, Arild Espenes, Martin JeffreyAbstract:Disease-associated prion protein (PrPd) in the enteric nervous system (ENS) of 20- to 24-month-old Suffolk Sheep in the late subclinical and early clinical phase of scrapie was studied. Sites in the alimentary tract extending from the forestomachs and abomasum to the colon from scrapie-affected Sheep (PrPARQ/ARQ) and scrapie-resistant Sheep (PrPARR/ARQ and PrPARR/ARR) were examined. PrPd was found only in scrapie-affected Sheep and was most prominent in the ENS when abundant deposits of PrPd were also present in adjacent lymphoid nodules. Immunolabelling with the nerve fibre markers PgP 9.5 and neuron-specific enolase and the satellite cell marker glial fibrillary acidic protein revealed the extensive ganglionated networks of the myenteric and submucosal plexi. Fewer nerve fibres were present in the lamina propria, T-cell dominated interfollicular areas and dome regions of Peyer's patches. A substantial network of nerve fibres was detected in many lymphoid nodules of both the scrapie-affected and scrapie-resistant Sheep. Nerve fibres were also detected within the capsule of lymphoid nodules. Electron microscopy revealed the presence of nerves in the lymphoid nodules, showing a close association with follicular dendritic cells, lymphocytes and tingible body macrophages. In demonstrating that lymphoid nodules in the Peyer's patches of scrapie-affected Sheep possess a substantial network of nerve fibres, the present study shows that nodules provide close contact between nerve fibres and cell populations known to contain abundant PrPd, including follicular dendritic cells and tingible body macrophages, and that gut-associated lymphoid nodules in Sheep may represent an important site for neuroinvasion.
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Distribution and accumulation of PrP in gut-associated and peripheral lymphoid tissue of scrapie-affected Suffolk Sheep.
Journal of General Virology, 2002Co-Authors: Ragna Heggebø, Lorenzo González, Charles Mcl. Press, Gjermund Gunnes, Martin JeffreyAbstract:The distribution of disease-associated prion protein (PrP) was investigated in eight animals (20–24 months of age) from a flock of Suffolk Sheep that had experienced frequent cases of natural scrapie over a period of several years. Tissue from the central nervous system (CNS), alimentary tract, peripheral nervous system and lymphoreticular system was examined by histopathology and immunohistochemistry. The lymphoid tissues were subjected further to histoblot and immunofluorescence examination. The four clinically affected PrPARQ/ARQ Sheep had widespread accumulations of disease-associated PrP in the CNS, lymphoreticular system and peripheral ganglia. In the two PrPARQ/ARQ Sheep that did not show clinical signs of scrapie, only limited vacuolation and PrP accumulation were detected in the brain, but the results from the lymphoreticular system and peripheral nervous system were comparable with the clinically affected animals. The remaining PrPARR/ARR and PrPARR/ARQ Sheep did not show proteinase K-resistant PrP accumulations in the lymphoid tissues examined and immunohistochemistry did not reveal the presence of disease-associated PrP. In lymphoid tissues of the PrPARQ/ARQ Sheep, the dominant localization of disease-associated PrP was in lymphoid nodules and double immunofluorescence labelling for PrP and CD21 provided further support for the role of follicular dendritic cells in scrapie in Sheep. A striking finding in the present study was the large accumulations of disease-associated PrP in the lymphoid nodules of the alimentary tract at the late sub-clinical and clinical stage of the infection. The study also identified disease-associated PrP in extra-nodular sites of lymphoid tissues, such as the marginal zone of the spleen, and these observations were used to argue that cells of the mononuclear phagocyte system of Sheep may be involved in the uptake, transport, elimination and shedding of the scrapie agent.
Martin Jeffrey - One of the best experts on this subject based on the ideXlab platform.
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Minimum Effective Dose of Cattle and Sheep BSE for Oral Sheep Infection.
PloS one, 2016Co-Authors: Gillian Mcgovern, Stuart Martin, Martin Jeffrey, G. Dexter, S.a.c. Hawkins, Sue J. Bellworthy, L. Thurston, Lynne Algar, Lorenzo GonzálezAbstract:The minimum dose required to cause infection of Romney and Suffolk Sheep of the ARQ/ARQ or ARQ/ARR prion protein gene genotypes following oral inoculation with Romney or Suffolk a Sheep Bovine spongiform encephalopathy (BSE)-derived or cattle BSE-derived agent was investigated using doses ranging from 0.0005g to 5g. ARQ/ARQ Sheep which were methionine (M) / threonine (T) heterozygous or T/T homozygous at codon 112 of the Prnp gene, dosed ARQ/ARR Sheep and undosed controls did not show any evidence of infection. Within groups of susceptible Sheep, the minimum effective oral dose of BSE was found to be 0.05g, with higher attack rates following inoculation with the 5g dose. Surprisingly, this study found no effect of dose on survival time suggesting a possible lack of homogeneity within the inoculum. All clinical BSE cases showed PrPd accumulation in brain; however, following cattle BSE inoculation, LRS involvement within Romney recipients was found to be significantly lower than within the Suffolk Sheep inoculated group which is in agreement with previous reports.
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Immunological differences between susceptible and resistant Sheep during the preclinical phase of scrapie infection.
Journal of General Virology, 2007Co-Authors: Samantha L. Eaton, Lorenzo González, Mark P. Dagleish, Jeanie Finlayson, Martin Jeffrey, M. Rocchi, S. Hamilton, Jill Sales, Philip Steele, S. M. RodgerAbstract:In order to investigate the relationship between the immune response to scrapie infection and genetic susceptibility to the disease in Sheep, immune cell subsets and prion protein (PrP) expression were determined in susceptible and resistant Suffolk Sheep in the preclinical phase of infection. At 6 months of age, 12 ARQ/ARQ (susceptible) and nine ARR/ARR (resistant) scrapie-free Suffolk lambs were challenged subcutaneously with scrapie inoculum. Prefemoral lymphadenectomies were carried out at 14 and 180 days post-inoculation (p.i.) and serial bleeds were collected at monthly intervals for up to 1 year p.i. An indirect double-labelling procedure was carried out on peripheral blood mononuclear cells (PBMCs) and lymph node cell preparations and analysed using flow cytometry. Prior to scrapie challenge, significantly more PrP+ cells were detected in PBMCs from the susceptible Sheep. Furthermore, following challenge, significantly more CD8+ and γδ + T cells were detected in the PBMCs of the resistant Sheep. However, at both 14 and 180 days p.i, CD21+ cell expression was significantly higher in the lymph node preparations of the susceptible Sheep. In contrast, more CD4+ cells were detected in the lymph nodes of the resistant Sheep at both time points. It was concluded that significant differences in immune cell subsets and PrP expression occur between ARQ/ARQ and ARR/ARR Suffolk Sheep in the preclinical phase of infection.
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Disease-associated PrP in the enteric nervous system of scrapie-affected Suffolk Sheep.
Journal of General Virology, 2003Co-Authors: Ragna Heggebø, Lorenzo González, Charles Mcl. Press, Gjermund Gunnes, Arild Espenes, Martin JeffreyAbstract:Disease-associated prion protein (PrPd) in the enteric nervous system (ENS) of 20- to 24-month-old Suffolk Sheep in the late subclinical and early clinical phase of scrapie was studied. Sites in the alimentary tract extending from the forestomachs and abomasum to the colon from scrapie-affected Sheep (PrPARQ/ARQ) and scrapie-resistant Sheep (PrPARR/ARQ and PrPARR/ARR) were examined. PrPd was found only in scrapie-affected Sheep and was most prominent in the ENS when abundant deposits of PrPd were also present in adjacent lymphoid nodules. Immunolabelling with the nerve fibre markers PgP 9.5 and neuron-specific enolase and the satellite cell marker glial fibrillary acidic protein revealed the extensive ganglionated networks of the myenteric and submucosal plexi. Fewer nerve fibres were present in the lamina propria, T-cell dominated interfollicular areas and dome regions of Peyer's patches. A substantial network of nerve fibres was detected in many lymphoid nodules of both the scrapie-affected and scrapie-resistant Sheep. Nerve fibres were also detected within the capsule of lymphoid nodules. Electron microscopy revealed the presence of nerves in the lymphoid nodules, showing a close association with follicular dendritic cells, lymphocytes and tingible body macrophages. In demonstrating that lymphoid nodules in the Peyer's patches of scrapie-affected Sheep possess a substantial network of nerve fibres, the present study shows that nodules provide close contact between nerve fibres and cell populations known to contain abundant PrPd, including follicular dendritic cells and tingible body macrophages, and that gut-associated lymphoid nodules in Sheep may represent an important site for neuroinvasion.
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Distribution and accumulation of PrP in gut-associated and peripheral lymphoid tissue of scrapie-affected Suffolk Sheep.
Journal of General Virology, 2002Co-Authors: Ragna Heggebø, Lorenzo González, Charles Mcl. Press, Gjermund Gunnes, Martin JeffreyAbstract:The distribution of disease-associated prion protein (PrP) was investigated in eight animals (20–24 months of age) from a flock of Suffolk Sheep that had experienced frequent cases of natural scrapie over a period of several years. Tissue from the central nervous system (CNS), alimentary tract, peripheral nervous system and lymphoreticular system was examined by histopathology and immunohistochemistry. The lymphoid tissues were subjected further to histoblot and immunofluorescence examination. The four clinically affected PrPARQ/ARQ Sheep had widespread accumulations of disease-associated PrP in the CNS, lymphoreticular system and peripheral ganglia. In the two PrPARQ/ARQ Sheep that did not show clinical signs of scrapie, only limited vacuolation and PrP accumulation were detected in the brain, but the results from the lymphoreticular system and peripheral nervous system were comparable with the clinically affected animals. The remaining PrPARR/ARR and PrPARR/ARQ Sheep did not show proteinase K-resistant PrP accumulations in the lymphoid tissues examined and immunohistochemistry did not reveal the presence of disease-associated PrP. In lymphoid tissues of the PrPARQ/ARQ Sheep, the dominant localization of disease-associated PrP was in lymphoid nodules and double immunofluorescence labelling for PrP and CD21 provided further support for the role of follicular dendritic cells in scrapie in Sheep. A striking finding in the present study was the large accumulations of disease-associated PrP in the lymphoid nodules of the alimentary tract at the late sub-clinical and clinical stage of the infection. The study also identified disease-associated PrP in extra-nodular sites of lymphoid tissues, such as the marginal zone of the spleen, and these observations were used to argue that cells of the mononuclear phagocyte system of Sheep may be involved in the uptake, transport, elimination and shedding of the scrapie agent.
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Onset and distribution of tissue PrP accumulation in Scrapie-affected Suffolk Sheep as demonstrated by sequential necropsies and tonsillar biopsies
Journal of comparative pathology, 2001Co-Authors: Martin Jeffrey, W S Dingwall, Stuart Martin, J. R. Thomson, I. Begara-mcgorum, Lorenzo GonzálezAbstract:Abstract Tonsillar biopsies (single or multiple) or necropsies, or both, were performed on Sheep taken from a Suffolk flock in which frequent cases of scrapie had occurred over a period of several years. Clinically affected Sheep of the susceptible PrP AQ/AQ genotype had widespread disease-specific PrP accumulation in the central nervous system (CNS), lymphoreticular system and peripheral ganglia. In nine healthy PrP AQ/AQ Suffolk Sheep between 4 and 7 years of age, PrP could not be demonstrated post mortem in any of the lymphoreticular tissues, or in the peripheral ganglia or CNS. Tonsillar biopsies taken from animals of the resistant PrP AR/AR and PrP AR/AQ genotypes at age 3, 8, 14, 20 or 26 months did not show PrP accumulation. Disease- specific PrP accumulation in tonsillar biopsies from PrP AQ/AQ Sheep was not seen in 20 animals aged 3 months, but was found in two of 10 animals at age 8 months and in eight of 10 animals at age 20 months. The numbers of PrP-positive tonsillar biopsies obtained from Sheep previously biopsied on more than one occasion was greater than the number of positive tonsils obtained from other susceptible Sheep of comparable ages. The earliest disease-specific PrP accumulation seen was in tingible body macrophages within germinal centres and only later was it detected in cells resembling follicular dendritic cells. Fourteen PrP AQ/AQ Sheep examined post mortem at up to 17 months of age and which had not previously been biopsied or were biopsied only once had no CNS or tonsillar PrP accumulations. Two of these Sheep subjected to necropsy at 14 months had PrP accumulation in lymphoreticular tissue, where it was confined to the mesenteric lymph nodes. In susceptible Sheep, only low levels of immunohistochemically detectable PrP were present in a minority of follicles from tonsillar biopsies of young lambs, but by 14 months of age widespread PrP accumulation, affecting many or even all follicles, was present. Although clinical cases had widespread PrP accumulations in viscera, susceptible survivors had no such accumulations in tissues of the lymphoreticular system, peripheral nervous system or CNS, suggesting that some animals were not exposed to infection or were exposed to a non-infectious dose.
Amir N. Hamir - One of the best experts on this subject based on the ideXlab platform.
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Oral inoculation of neonatal Suffolk Sheep with the agent of classical scrapie results in PrP(Sc) accumulation in Sheep with the PRNP ARQ/ARQ but not the ARQ/ARR genotype.
Research in veterinary science, 2016Co-Authors: Justin J. Greenlee, Jodi D. Smith, Amir N. HamirAbstract:Scrapie is a transmissible spongiform encephalopathy that can be transmitted amongst susceptible Sheep. The prion protein gene (PRNP) profoundly influences the susceptibility of Sheep to the scrapie agent. This study reports the failure to detect PrP(Sc) in nervous or lymphoid tissues of Suffolk Sheep of the PRNP ARQ/ARR genotype after oral inoculation with a U.S. scrapie isolate. Lambs were inoculated within the first 24 h of birth with 1 ml of a 10% (wt./vol.) brain homogenate derived from a clinically affected ARQ/ARQ Sheep. The inoculated Sheep were observed daily throughout the experiment for clinical signs suggestive of scrapie until they were necropsied at 86 months post inoculation. Tissues were collected for examination by immunohistochemistry and enzyme immunoassay, but all failed to demonstrate evidence of scrapie infection. Neonatal Sheep of the ARQ/ARQ genotype receiving the same inoculum developed scrapie within 24 months. Lambs of the ARQ/ARR genotype that received the same inoculum by intracranial inoculation develop scrapie with a prolonged incubation period and with abnormal prion present within the central nervous system, but not peripheral lymphoid tissues. Results of this study suggest that ARQ/ARR Sheep are resistant to oral infection with the scrapie isolate used even during the neonatal period.
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Cartilaginous metaplasia in the sclera of Suffolk Sheep.
Veterinary pathology, 2010Co-Authors: Jodi D. Smith, Amir N. Hamir, Justin J. GreenleeAbstract:Scleral cartilaginous metaplasia was detected by routine histologic examination of globes from 5 Suffolk Sheep from a scrapie pathogenesis study. The extent of the metaplasia varied among the Sheep but was always posterior to the tapetal fundus. The matrix surrounding chondrocytes stained intensely with alcian blue and was immunopositive for type II collagen. Retrospective evaluation of additional eyes from Suffolk and Cheviot Sheep used in various scrapie pathogenesis studies at the authors' facility revealed similar histologic changes in 40% and 12.7% of eyes examined, respectively. The clinical significance of this previously unreported finding is unknown.
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Altered electroretinogram b-wave in a Suffolk Sheep experimentally infected with scrapie.
The Veterinary record, 2009Co-Authors: Jodi D. Smith, Amir N. Hamir, Justin J. Greenlee, M. H. West GreenleeAbstract:TRANSMISSIBLE spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative diseases in which an abnormal isoform of the cellular prion protein (PrPSc) accumulates in tissues of the central nervous system. Accumulation of PrPSc occurs in the retina, a rostral projection of the central
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Serial passage of Sheep scrapie inoculum in Suffolk Sheep.
Veterinary pathology, 2009Co-Authors: Amir N. Hamir, Robert A. Kunkle, Juergen A. Richt, Justin J. Greenlee, Janice M. MillerAbstract:Scrapie is a naturally occurring fatal neurodegenerative disease of Sheep and goats. Susceptibility to the disease is partly dependent upon the genetic makeup of the host. In a recent study, it was shown that Sheep intracerebrally inoculated with a US scrapie agent (No. 13–7) developed scrapie and survived for an average of 19 months post inoculation. In the present study, when this scrapie inoculum was further passaged for 3 successive generations, the survival time was reduced by approximately 8 months in scrapie-susceptible (QQ on prion protein gene [PRNP] at codon 171) Suffolk Sheep. It is concluded that inoculum No. 13–7 appears to have been stabilized in susceptible (171 QQ) Suffolk Sheep and may be considered a specific isolate of Sheep scrapie agent in the USA and therefore that it can be used to evaluate other isolates of Sheep scrapie in this country.
Ming-xing Chu - One of the best experts on this subject based on the ideXlab platform.
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DNA polymorphism of 5' flanking region of prolactin gene and its association with litter size in Sheep.
Journal of animal breeding and genetics = Zeitschrift fur Tierzuchtung und Zuchtungsbiologie, 2009Co-Authors: Ming-xing Chu, X.c. Wang, Mei Jin, Hongquan Chen, G.q. Zhu, Li FangAbstract:Summary A single nucleotide polymorphism of 5¢ flanking region of the prolactin gene was investigated in both high prolificacy breeds (Small Tail Han and Hu Sheep) and low prolificacy breeds (Dorset and Suffolk Sheep) using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP). The results indicated that two genotypes (AA and AB) were detected in Small Tail Han Sheep (n = 239), only one genotype (AA) was detected in Hu (n = 40), Dorset (n = 50) and Suffolk Sheep (n = 39). The mutant homozygous genotype (BB) was not detected in four Sheep breeds. In Small Tail Han Sheep (n = 239), the frequency of genotypes AA and AB was 0.91 and 0.09, the frequency of the A and B alleles was 0.95 and 0.05, respectively. The fitness tests showed that the Small Tail Han Sheep population was in Hardy‐Weinberg equilibrium. Sequencing revealed a mutation (G fi T) at the position 63 bp of the 5¢ flanking region of prolactin gene in AB genotype compared with AA genotype in Small Tail Han Sheep. The Small Tail Han ewes with AB genotype had 0.83 (p < 0.05) lambs more than those with AA genotype. These results preliminarily showed that the prolactin locus is either a major gene that influences the high prolificacy in Small Tail Han Sheep or is in close linkage with such a gene.
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Estrogen Receptor as a Candidate Gene for Prolificacy of Small Tail Han Sheep
Yi chuan xue bao = Acta genetica Sinica, 2005Co-Authors: Ming-xing Chu, Hai-guo Jin, Li FangAbstract:Single nucleotide polymorphism in exon 1 of the estrogen receptor (ESR) gene was detected by PCR-SSCP in both high fecundity Sheep breeds (Small Tail Han Sheep, Hu Sheep and German Mutton Merino Sheep) and low fecundity Sheep breeds (Dorset Sheep,Suffolk Sheep). Results indicated that there were three genotypes (AA, AB and BB) in all three high fecundity Sheep breeds, but only two genotypes (AA, AB) in both low fecundity breeds. In Hu Sheep,German Mutton Merino Sheep, Small Tail Han Sheep, Suffolk Sheep and Dorset Sheep,the frequency of allele A was 0.672, 0.786, 0.846, 0.857 and 0.867, respectively, and the frequency of allele B was 0.328, 0.214, 0.154, 0.143, and 0.133, respectively. Sequencing revealed a C-->G mutation at 363 bp of exon 1 of ESR gene in the BB genotype in comparison to the AA genotype. The genotype distribution was significantly different between Small Tail Han Sheep and Hu Sheep (P
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Genetic relationships among seven Sheep populations using four microsatellite markers
Yi chuan = Hereditas, 2004Co-Authors: Ji-zhen Wang, Ming-xing Chu, Ai-guo Wang, Fang Xie, Guo-hong ChenAbstract:The genetic polymorphisms of four microsatellite loci BM143, OarHH35, OarAE101, and BMS2508 were analyzed in 286 Sheep of seven Sheep populations (Small Tail Han Sheep, Hu Sheep, Ujumqin Sheep, Suffolk Sheep, Dorset Sheep, Charolais Sheep, F1 of Dorset male x Small Tail Han female Sheep). The numbers of alleles for BM143, OarHH35, OarAE101, and BMS2508 are 9, 11, 14 and 9 in seven Sheep populations, respectively. The polymorphism information content/number of effective alleles/ heterozygosity of BM143, OarHH35, OarAE101 and BMS2508 were 0.7073/3.7231/0.7314, 0.8267/6.4399/0.8447, 0.5743/2.5178/0.6028, 0.6172/3.0712/0.6744 in 286 Sheep, respectively. The results revealed the greatest genetic variation at OarHH35 locus and the lowest at OarAE101, the greatest genetic variation in Small Tail Han Sheep and the lowest in Hu Sheep among seven Sheep populations. In the unweighted pair group method with arithmetic mean (UPGMA) dendrograms based on Nei's D(A) distance and Nei's D(S) standard genetic distance, the Chinese native breeds (Small Tail Han Sheep, Ujumqin Sheep, Hu Sheep) were grouped together, then with Charolais Sheep. The F1 crossbred Sheep, and the two British native Sheep (Suffolk Sheep, Dorset Sheep) also clustered together. Microsatellite genotyping in Sheep provided a useful tool for examining the genetic relationships among breeds (populations).
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PCR-SSCP analysis on growth differentiation factor 9 gene in Sheep
Yi chuan xue bao = Acta genetica Sinica, 2003Co-Authors: Ming-xing Chu, Jin-yu WangAbstract:Growth differentiation factor 9 (GDF9) is a growth factor secreted by oocytes in growing ovarian follicles, which is essential for growth and differentiation of early ovarian follicles. The polymorphism of GDF9 gene in Small Tail Han Sheep, Hu Sheep, Dorset Sheep and Suffolk Sheep was analyzed by PCR-SSCP. The results indicated that there were three genotypes (AA, AB and BB) detected by primer 1. AA genotype was detected in four Sheep breeds. AB genotype was detected in Hu Sheep, Dorset Sheep and Suffolk Sheep. BB genotype was only detected in Suffolk Sheep. Frequency of A allele was obviously higher than frequency of B allele in four Sheep breeds. There were two genotypes (AA and AB) detected by primer 2. AA genotype was detected in four Sheep breeds. AB genotype was detected in Hu Sheep, Dorset Sheep and Suffolk Sheep. BB genotype was not detected in four Sheep breeds. Frequency of AA genotype was the highest, and frequency of A allele was obviously higher than frequency of B allele in four Sheep breeds. The polymorphic fragments amplified by primer 1 were cloned and sequenced. The sequencing results showed that there was one single nucleotide mutation: A-->G at cDNA 152 of GDF9 gene in Sheep, and this mutation resulted in an amino acid change: asparagine-->aspartic acid.
Stuart Martin - One of the best experts on this subject based on the ideXlab platform.
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Minimum Effective Dose of Cattle and Sheep BSE for Oral Sheep Infection.
PloS one, 2016Co-Authors: Gillian Mcgovern, Stuart Martin, Martin Jeffrey, G. Dexter, S.a.c. Hawkins, Sue J. Bellworthy, L. Thurston, Lynne Algar, Lorenzo GonzálezAbstract:The minimum dose required to cause infection of Romney and Suffolk Sheep of the ARQ/ARQ or ARQ/ARR prion protein gene genotypes following oral inoculation with Romney or Suffolk a Sheep Bovine spongiform encephalopathy (BSE)-derived or cattle BSE-derived agent was investigated using doses ranging from 0.0005g to 5g. ARQ/ARQ Sheep which were methionine (M) / threonine (T) heterozygous or T/T homozygous at codon 112 of the Prnp gene, dosed ARQ/ARR Sheep and undosed controls did not show any evidence of infection. Within groups of susceptible Sheep, the minimum effective oral dose of BSE was found to be 0.05g, with higher attack rates following inoculation with the 5g dose. Surprisingly, this study found no effect of dose on survival time suggesting a possible lack of homogeneity within the inoculum. All clinical BSE cases showed PrPd accumulation in brain; however, following cattle BSE inoculation, LRS involvement within Romney recipients was found to be significantly lower than within the Suffolk Sheep inoculated group which is in agreement with previous reports.
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influence of breed and genotype on the onset and distribution of infectivity and disease associated prion protein in Sheep following oral infection with the bovine spongiform encephalopathy agent
Journal of Comparative Pathology, 2015Co-Authors: Gillian Mcgovern, Stuart Martin, Sue J. Bellworthy, L. Thurston, M Jeffrey, John Spiropoulos, Robert B Green, Richard Lockey, Christopher M Vickery, G. DexterAbstract:The onset and distribution of infectivity and disease-specific prion protein (PrPd) accumulation was studied in Romney and Suffolk Sheep of the ARQ/ARQ, ARQ/ARR and ARR/ARR prion protein gene (Prnp) genotypes (where A stands for alanine, R for arginine and Q for glutamine at codons 136, 154 and 171 of PrP), following experimental oral infection with cattle-derived bovine spongiform encephalopathy (BSE) agent. Groups of Sheep were killed at regular intervals and a wide range of tissues taken for mouse bioassay or immunohistochemistry (IHC), or both. Bioassay results for infectivity were mostly coincident with those of PrPd detection by IHC both in terms of tissues and time post infection. Neither PrPd nor infectivity was detected in any tissues of BSE-dosed ARQ/ARR or ARR/ARR Sheep or of undosed controls. Moreover, four ARQ/ARQ Suffolk Sheep, which were methionine (M)/threonine heterozygous at codon 112 of the Prnp gene, did not show any biological or immunohistochemical evidence of infection, while those homozygous for methionine (MARQ/MARQ) did. In MARQ/MARQ Sheep of both breeds, initial PrPd accumulation was identified in lymphoreticular system (LRS) tissues followed by the central nervous system (CNS) and enteric nervous system (ENS) and finally by the autonomic nervous system and peripheral nervous system and other organs. Detection of infectivity closely mimicked this sequence. No PrPd was observed in the ENS prior to its accumulation in the CNS, suggesting that ENS involvement occurred simultaneously to that of, or followed centrifugal spread from, the CNS. The distribution of PrPd within the ENS further suggested a progressive spread from the ileal plexus to other ENS segments via neuronal connections of the gut wall. Differences between the two breeds were noted in terms of involvement of LRS and ENS tissues, with Romney Sheep showing a more delayed and less consistent PrPd accumulation than Suffolk Sheep in such tissues. Whether this accounted for the slight delay (∼5 months) in the appearance of clinical signs in Romney Sheep is debatable since by the last scheduled kill before animals reached clinical end point, both breeds showed widespread accumulation and similar magnitudes of PrPd accumulation in the brain.
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Factors influencing temporal variation of scrapie incidence within a closed Suffolk Sheep flock
Journal of General Virology, 2012Co-Authors: Lorenzo González, Mark P. Dagleish, Stuart Martin, Jeanie Finlayson, Sílvia Sisó, Samantha L. Eaton, Wilfred Goldmann, Janey Witz, Scott L. Hamilton, Paula StewartAbstract:Several studies have shown that transmission of natural scrapie can occur vertically and horizontally, and that variations in scrapie incidence between and within infected flocks are mostly due to differences in the proportion of Sheep with susceptible and resistant PRNP genotypes. This report presents the results of a 12-year period of scrapie monitoring in a closed flock of Suffolk Sheep, in which only animals of the ARQ/ARQ genotype developed disease. Among a total of 120 of these, scrapie attack rates varied between birth cohorts from 62.5% (5/8) to 100% (9/9), and the incidence of clinical disease among infected Sheep from 88.9% (8/9) to 100% (in five birth cohorts). Susceptible Sheep born to scrapie-infected ewes showed a slightly higher risk of becoming infected (97.2%), produced earlier biopsy-positive results (mean 354 days) and developed disease at a younger age (median 736 days) than those born to non-infected dams (80.3%, 451 and 782 days, respectively). Taken together, this was interpreted as evidence of maternal transmission. However, it was also observed that, for the birth cohorts with the highest incidence of scrapie (90–100%), Sheep born to infected and non-infected dams had a similar risk of developing scrapie (97.1 and 95.3%, respectively). Compared with moderate-attack-rate cohorts (62.5–66.7%), high-incidence cohorts had greater numbers of susceptible lambs born to infected ewes, suggesting that increased rates of horizontal transmission in these cohorts could have been due to high levels of environmental contamination caused by infected placentas.
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Onset and distribution of tissue PrP accumulation in Scrapie-affected Suffolk Sheep as demonstrated by sequential necropsies and tonsillar biopsies
Journal of comparative pathology, 2001Co-Authors: Martin Jeffrey, W S Dingwall, Stuart Martin, J. R. Thomson, I. Begara-mcgorum, Lorenzo GonzálezAbstract:Abstract Tonsillar biopsies (single or multiple) or necropsies, or both, were performed on Sheep taken from a Suffolk flock in which frequent cases of scrapie had occurred over a period of several years. Clinically affected Sheep of the susceptible PrP AQ/AQ genotype had widespread disease-specific PrP accumulation in the central nervous system (CNS), lymphoreticular system and peripheral ganglia. In nine healthy PrP AQ/AQ Suffolk Sheep between 4 and 7 years of age, PrP could not be demonstrated post mortem in any of the lymphoreticular tissues, or in the peripheral ganglia or CNS. Tonsillar biopsies taken from animals of the resistant PrP AR/AR and PrP AR/AQ genotypes at age 3, 8, 14, 20 or 26 months did not show PrP accumulation. Disease- specific PrP accumulation in tonsillar biopsies from PrP AQ/AQ Sheep was not seen in 20 animals aged 3 months, but was found in two of 10 animals at age 8 months and in eight of 10 animals at age 20 months. The numbers of PrP-positive tonsillar biopsies obtained from Sheep previously biopsied on more than one occasion was greater than the number of positive tonsils obtained from other susceptible Sheep of comparable ages. The earliest disease-specific PrP accumulation seen was in tingible body macrophages within germinal centres and only later was it detected in cells resembling follicular dendritic cells. Fourteen PrP AQ/AQ Sheep examined post mortem at up to 17 months of age and which had not previously been biopsied or were biopsied only once had no CNS or tonsillar PrP accumulations. Two of these Sheep subjected to necropsy at 14 months had PrP accumulation in lymphoreticular tissue, where it was confined to the mesenteric lymph nodes. In susceptible Sheep, only low levels of immunohistochemically detectable PrP were present in a minority of follicles from tonsillar biopsies of young lambs, but by 14 months of age widespread PrP accumulation, affecting many or even all follicles, was present. Although clinical cases had widespread PrP accumulations in viscera, susceptible survivors had no such accumulations in tissues of the lymphoreticular system, peripheral nervous system or CNS, suggesting that some animals were not exposed to infection or were exposed to a non-infectious dose.
