LILIAN DE OLIVEIRA GUIMARAES
Projetos de Pesquisa
Unidades Organizacionais
LIM/49 - Laboratório de Protozoologia, Hospital das Clínicas, Faculdade de Medicina
3 resultados
Resultados de Busca
Agora exibindo 1 - 3 de 3
- Higher infection probability of haemosporidian parasites in Blue-black Grassquits (Volatinia jacarina) inhabiting native vegetation across Brazil(2021) FECCHIO, Alan; RIBEIRO, Rayanne M.; FERREIRA, Francisco C.; DUTRA, Daniela de Angeli; TOLESANO-PASCOLI, Graziela; ALQUEZAR, Renata D.; KHAN, Asmat U.; PICHORIM, Mauro; MOREIRA, Patricia A.; COSTA-NASCIMENTO, Maria J.; MONTEIRO, Eliana F.; MATHIAS, Bruno S.; GUIMARAES, Lilian O.; SIMOES, Roseli F.; BRAGA, Erika M.; KIRCHGATTER, Karin; DIAS, Raphael I.Human induced changes on landscape can alter the biotic and abiotic factors that influence the transmission of vector-borne parasites. To examine how infection rates of vector-transmitted parasites respond to changes on natural landscapes, we captured 330 Blue-black Grassquits (Volatinia jacarina) in Brazilian biomes and assessed the prevalence and diversity of avian haemosporidian parasites (Plasmodium and Haemoproteus) across avian host populations inhabiting environment under different disturbance and climatic conditions. Overall prevalence in Blue-black Grassquits was low (11%) and infection rates exhibited considerable spatial variation, ranging from zero to 39%. Based on genetic divergence of cytochrome b gene, we found two lineages of Haemoproteus (Parahaemoproteus) and 10 of Plasmodium. We showed that Blue-black Grassquit populations inhabiting sites with higher proportion of native vegetation cover were more infected across Brazil. Other landscape metrics (number of water bodies and distance to urban areas) and climatic condition (temperature and precipitation) known to influence vector activity and promote avian malaria transmission did not explain infection probability in Blue-black Grassquit populations. Moreover, breeding season did not explain prevalence across avian host populations. Our findings suggest that avian haemosporidian prevalence and diversity in Blue-black Grassquit populations are determined by recent anthropogenic changes in vegetation cover that may alter microclimate, thus influencing vector activity and parasite transmission.
- Genetic ancestry effects on the distribution of toll-like receptors (TLRs) gene polymorphisms in a population of the Atlantic Forest, Sao Paulo, Brazil(2018) GUIMARAES, Lilian O.; BAJAY, Miklos Maximiliano; MONTEIRO, Eliana F.; WUNDERLICH, Gerhard; SANTOS, Sidney E.; KIRCHGATTER, KarinThe innate immune system governed by toll -like receptors (TLRs) provides the first line of defense against pathogens. Surface -localized TLR1 and TLR6 are known to detect parasite components. TLR encoding genes were shown to display signatures of recent positive selection in Europeans and might be involved in local adaptation at immune -related genes. To verify the influence of Brazilian population admixture on the distribution of polymorphisms in TLRs, we analyzed the genotype frequencies of 24 polymorphisms distributed across five TLR genes in a Southeastern Brazilian population where autochthonous cases of malaria occur in small foci of transmission. The estimation of ancestry showed mainly European ancestry (63%) followed by African ancestry (22%). Mean proportions of European ancestry differed significantly between the genotypes of the TLR1 (1602S) gene and in the TLR6 (P249S) gene. The chance of having the G allele in TLR1 gene increases as European ancestry increases as well as the chance of having the T allele in the TLR6 gene. The 602S allele is related to a ""hypo -responsiveness"" possibly explaining the high prevalence of asymptomatic malaria cases in areas of Southeastern Brazil. Our results underline the necessity to include informative ancestry markers in genetic association studies in order to avoid biased results.
- Influence of polymorphisms in toll-like receptors (TLRs) on malaria susceptibility in low-endemic area of the Atlantic Forest, Sao Paulo, Brazil(2018) GUIMARAES, Lilian O.; FERNANDES, Francisco; MONTEIRO, Eliana F.; CURADO, Izilda; HOLCMAN, Marcia M.; WUNDERLICH, Gerhard; SANTOS, Sidney E.; SOLER, Julia M.; KIRCHGATTER, KarinIn low-endemic areas for malaria transmission, asymptomatic individuals play an important role as reservoirs for malarial infection. Understanding the dynamics of asymptomatic malaria is crucial for its efficient control in these regions. Genetic host factors such as Toll-like receptor CUR) polymorphisms may play a role in the maintenance or elimination of infection. In this study, the effect of TLR polymorphisms on the susceptibility to malaria was investigated among individuals living in the Atlantic Forest of Sao Paulo, Southern Brazil. A hundred and ninety-five Brazilian individuals were enrolled and actively followed up for malaria for three years. Twenty-four polymorphisms in five toll-like receptor (TLR) genes were genotyped by RFLP, direct sequencing or fragment analysis. The genotypes were analyzed for the risk of malaria. Ongoing Plasmodium vivax or P. malaria infection, was identified by the positive results in PCR tests and previous P. vtvax malaria, was assumed when antiplasmodial antibodies against PvMSP1(19) were detected by ELISA. An evaluation of genomic ancestry was conducted using biallelic ancestry informative markers and the results were used as correction in the statistical analysis. Nine SNPs and one microsatellite were found polymorphic and three variant alleles in TLR genes were associated to malaria susceptibility. The regression coefficient estimated for SNP TLR9.-1237.T/C indicated that the presence of at least one allele C increased, on average, 2.3 times the malaria odds, compared to individuals with no allele C in this SNP. However, for individuals with the same sex, age and household, the presence of at least one allele C in SNP TLR9.-1486.T/C reduced, on average, 1.9 times the malaria odds, compared to individuals with no allele C. Moreover, this allele C plus an S allele in TLR6.P249S in individuals with same sex, age and ancestry, reduced, on average, 4.4 times the malaria odds. Our findings indicate a significant association of TLR9.-1237.T/C gene polymorphism with malarial infection and contribute to a better knowledge of the role of TLRs in malaria susceptibility in an epidemiological setting different from other settings.