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Biology subjects

Brazeau, N. F.

Publications and source records attributed to Brazeau, N. F..

3 recordsLinked to original sources

Genomic insights into Plasmodium vivax population structure and diversity in central Africa

Plasmodium vivax malaria has not traditionally been a major concern in central Africa given the high prevalence of the human Duffy-negative phenotype that is believed to prevent infection. Increasing reports of asymptomatic and symptomatic infections in Duffy-negative individuals throughout Africa raise the possibility that P. vivax is evolving to evade host resistance, but there are few parasite samples with genomic data available from this part of the world. In this study, we perform whole genome sequencing of a new P. vivax isolate from the Democratic Republic of the Congo (DRC) and assess how this central African isolate fits into the global context of this species. We use population genomics methods to show that P. vivax from DRC is similar to other African parasite populations and is not closely related to the non-human primate parasite P. vivax-like. SignificanceThe second most common malaria species to infect humans, Plasmodium vivax, is not considered a major threat to human health in central Africa because people in this region frequently have a genetic variant that prevents the P. vivax species from being able to cause illness. Recent research shows that P. vivax can be found in individuals who should be immune, but there is insufficient data to understand why. Our study investigates the genome of one P. vivax sample collected from central Africa to show that the DRC population is closely related to other P.vivax populations in Africa.

evolutionary biology↗

Falciparum malaria from coastal Tanzania and Zanzibar remains highly connected despite effective control efforts on the archipelago

BackgroundTanzanias Zanzibar archipelago has made significant gains in malaria control over the last decade and is a target for malaria elimination. Despite consistent implementation of effective tools since 2002, elimination has not been achieved. Importation of parasites from outside of the archipelago is thought to be an important cause of malarias persistence, but this paradigm has not been studied using modern genetic tools. MethodsWe used whole-genome sequencing (WGS) to investigate the impact of importation, employing population genetic analyses of Plasmodium falciparum isolates from both the archipelago and mainland Tanzania. We assessed ancestry, levels of genetic diversity and differentiation, patterns of relatedness, and patterns of selection between these two populations by leveraging recent advances in deconvolution of genomes from polyclonal malaria infections. ResultsWe identified significant decreases in the effective population sizes in both populations in the timeframe of decreasing malaria transmission in Tanzania. Identity by descent analysis showed that parasites in the two populations shared large sections of their genomes, on the order of 5 cM, suggesting shared ancestry within the last 10 generations. Even with limited sampling,, we demonstrate a pair of isolates between the mainland and Zanzibar that are related at the expected level of half-siblings, consistent with recent importation ConclusionsThese findings suggest that importation plays an increasing role for malaria incidence on Zanzibar and demonstrate the value of genomic approaches for identifying corridors of parasite movement to the island.

genetics↗

The Impact of Antimalarial Resistance on the Genetic Structure of Plasmodium falciparum in the DRC

The Democratic Republic of the Congo (DRC) harbors 11% of global malaria cases, yet little is known about the spatial and genetic structure of the parasite population in that country. We sequenced 2537 Plasmodium falciparum infections, including a nationally representative population sample from DRC and samples from surrounding countries, using molecular inversion probes - a novel high-throughput genotyping tool. We identified an east-west divide in haplotypes known to confer resistance to chloroquine and sulfadoxine-pyrimethamine. Furthermore, we identified highly related parasites over large geographic distances, indicative of gene flow and migration. Our results were consistent with a background of isolation by distance combined with the effects of selection for antimalarial drug resistance. This study provides a high-resolution view of parasite genetic structure across a large country in Africa and provides a baseline to study how implementation programs may impact parasite populations.

genomics↗