Plasmodium falciparum genetic diversity - Marc Antoine Guery- ASTMH 2020 скачать в хорошем качестве

Plasmodium falciparum genetic diversity - Marc Antoine Guery- ASTMH 2020

Presentation of Marc Antoine GUERY at ASTMH - November 2020 Plasmodium falciparum genetic diversity is regenerated during the wet season in the Upper River Region of The Gambia Marc-Antoine Guery, Sainabou Drammeh, Sukai Ceesay, Fatou K Jaiteh, Umberto d´Alessandro, Teun Bousema, Dominic Kwiatkowski, Julia Mwesigwa, Antoine Claessens Abstract: Understanding malaria transmission mechanisms is a necessary step to malaria control and elimination. In countries like The Gambia where malaria is seasonal, rainfall greatly affects the total number of cases, yet little is known about the impact on the Plasmodium falciparum genetic diversity. To address this question, we conducted a longitudinal study in four nearby villages in the Upper River Region of The Gambia from 2014 to 2017. Blood samples from 581 participants over 16 time points were collected during both wet and dry seasons. In total, 515 P. falciparum positive samples from asymptomatic infections were successfully genotyped by sequencing 84 SNPs and 255 were whole genome sequenced at the Sanger Institute (MalariaGEN). We used identity by descent (IBD), a pairwise comparison method to estimate the relationships between genotyped and sequenced isolates. Average IBD was unexpectedly low, suggesting a high diversity of parasites despite a limited studied area. Parasite samples collected within the same household were not significantly more genetically related, indicating that people sleeping under the same roof are not at increased risk of transmitting a particular parasite strain to each other. Also, parasites isolated during the dry seasons were more related to the preceding wet season than to the following one. This suggests that dry seasons may be a reservoir of parasites waiting for the transmission season to recombine, hence renewing genetic diversity at every wet season. The parasite similarities between each pair of time points steadily decreased with the time separating the two time points. We could then estimate that most of the parasite diversity renewed after approximately one year. An interesting exception is a 9-year old individual who had been infected with the same parasite for at least 1 year and a half. According to our findings, dry seasons are the period where parasites are in a latency phase with most of the infections being asymptomatic. We argue that longitudinal studies are key to understand asymptomatic chronic infections, the ‘invisible reservoir’ of malaria. Team website : https://lphi.umontpellier.fr/fr/les-e... ASTMH website : https://www.astmh.org