Percorrer por autor "Moreira, Guilherme"
A mostrar 1 - 3 de 3
Resultados por página
Opções de ordenação
- Mapping PRNP Polymorphisms in Portuguese Serra da Estrela Ovine Populations: Insights into Scrapie Susceptibility and Farm Animal ImprovementPublication . Rodrigues, Soraia; Moreira, Guilherme; Santos-Silva, Sérgio; Gomes-Gonçalves, Sara; Aires Pereira, Maria; Baptista, Alexandra; Cruz, Rita; Esteves, Fernando; Mesquita, João R.Scrapie (classical and atypical) susceptibility in sheep is strongly influenced by PRNP gene polymorphisms. In Portugal, limited data exist for native breeds such as Serra da Estrela, despite their relevance to animal conservation and food production. The full coding region of PRNP gene of 92 Serra da Estrela sheep was sequenced and SNP frequencies were analysed. The predicted functional impact of nonsynonymous SNPs was assessed using PolyPhen-2 and AMYCO. A total of 27 SNPs were identified, including 20 nonsynonymous variants. Thirteen major haplotypes were observed. The ARR allele, which provides resistance to classical scrapie, was present in 58.7% of the population, with 18.5% of animals being homozygous. Several previously unreported SNPs were identified, and their impact on prion protein aggregation propensity and structure was explored. The high frequency of the ARR allele without full ARR fixation suggests that no selective breeding for scrapie resistance has been applied. These results support the adoption of gradual selection strategies that preserve genetic variability and promote farmer compliance, while increasing classical and atypical scrapie resistance.
- Targeted-Amplicon NGS for Blastocystis sp. in Shepherd Dogs of Portugal Discriminates Co-Colonization with Multiple Zoonotic SubtypesPublication . Gomes-Gonçalves, Sara; Feiteiro, Maria João; Moreira, Guilherme; Cruz, Rita; Esteves, Fernando; Vala Correia, Helena Maria; Mesquita, João R.Research on endoparasites in pet dogs has been growing, but shepherd dogs have largely been overlooked. These dogs frequently share close proximity not only with sheep, which are reservoirs of zoonotic subtypes of Blastocystis, but also with their owners. This close contact increases the potential for shepherd dogs to act as intermediates in the transmission of Blastocystis. To clarify the role of these dogs as reservoirs for this parasite, this study investigated the presence of Blastocystis in shepherd dogs. Stool samples from Portuguese shepherd dogs were analyzed using SYBR-Green-based real-time PCR and melting curve analysis followed by targeted-amplicon NGS for mixed infections detection. Our results revealed a 60% occurrence of Blastocystis sp. in shepherd dog stools and frequent identification of zoonotic subtypes ST1–ST4 and ST14. Additionally, we observed mixed infections and subtype diversity within individual dogs, suggesting a potential role in cross-species transmission between livestock and humans.
- Toxoplasma Gondii In Shepherds and Cheesemakers – A Case-Control Study on Sheep-Associated Occupational Exposure in Central PortugalPublication . Moreira, Guilherme; Almeida, Daniela; Cruz, Rita; Nóbrega, Carmen; Arede dos Santos, Carla Sofia; Coelho, Catarina; Mega, Cristina; Pereira, Maria; Esteves, Fernando; Vala Correia, Helena Maria; Cardoso, Luís; Lopes, Ana P.; Coelho, Ana C.; Mesquita, João R.Objectives: The primary objective of this study was to determine if workers occupationally exposed (WOE) to sheep, specifically shepherds and cheesemakers in central Portugal, are more likely to be seropositive for anti-Toxoplasma gondii IgG compared to the general population. Additionally, the study aimed to explore potential differences in seropositivity between shepherds and cheesemakers, while evaluating age, gender, and activity as possible risk factors for T. gondii infection. Methods: A total of 96 WOE, including 21 shepherds and 75 cheesemakers, were tested for anti-T. gondii IgG using a commercial enzyme-linked immunosorbent assay (ELISA). The control group consisted of 192 sera samples from blood donors matched by age, gender, and residence. Chi-square tests with Yates correction were used to compare seroprevalence between WOE and the general population, and between shepherds and cheesemakers. Univariate and multivariable logistic regression analyses were performed to evaluate potential associations between T. gondii seropositivity and factors such as activity, gender, and age. Results: The overall seroprevalence was 63.5% in the WOE and 52.6% in the general population, with no statistically significant difference (p = .101). Among WOE, 52.4% of shepherds and 66.7% of cheesemakers were seropositive, with no significant difference between the two groups (p = .344). Univariate and multivariable analyses indicated neither activity, age, nor gender were significant risk factors for seropositivity in the case population. Conclusion: The study did not find a significant increased risk of T. gondii seropositivity among shepherds and cheesemakers compared to the general population. While high seroprevalence was observed in both groups, other factors unrelated to occupational exposure may be influencing the risk of T. gondii infection. More research is needed, particularly focusing on cheesemakers, to further explore potential occupational health risks related to T. gondii.