The working group of Dr Silvia Portugal is interested in the biology and the life cycle of Plasmodium falciparum, a parasite that causes severe Malaria tropica. This type of Malaria often comes along with complications and a severe course of the infection. Silvia Portugal studies the host and parasite factors that influence persisting clinically silent P. falciparum parasitaemias during the dry season. Especially in regions where people are confronted with the parasite for a long time, you can find a lot of these infected people without symptoms.
The scientists compare the properties and function of P. falciparum parasites freshly isolated from asymptomatic individuals during the dry season in Mali versus symptomatic individuals during the malaria season. They make use of genome-wide expression and metabolome profiling, and evaluate functionally the parasite‘s ability to grow, transmit, or induce a host immune response.
We propose to explore the reservoir of P. falciparum infection that is maintained asymptomatically during the dry season in close to a third of the children in Mali, allowing transmission to restart once the mosquito returns when the wet season ensues.
Survival during the dry season
The main question driving our lab is “How does the parasite stay at low parasitaemias for periods as long as 6 months without causing symptoms it being cleared by the immune system?” Tackling this question may have an enormous impact on the development of strategies to control and eliminate malaria in areas of seasonal transmission. We propose to explore the reservoir of P. falciparum infection that is maintained asymptomatically during the dry season in close to a third of the children in Mali, allowing transmission to restart once the mosquito returns when the wet season ensues.
Our hypothesis is that during the dry season parasite factors contribute to keep low parasite densities but prevent total clearance, hence increasing the parasite’s probability of reaching the next transmission season. To better understand this, we compared P. falciparum freshly isolated from asymptomatic individuals during the dry season vs. symptomatic individuals during the malaria season.
A different program
We observe that P. falciparum is indeed under a different program during the dry season, with a very large number of protein-coding genes appearing differently expressed seasonally, and a much different circulating metabolic profile. Our overarching goal is now to clarify the mechanisms which allow parasite survival for long periods without causing symptoms, as well as promote sexual differentiation that restarts transmission as the mosquito vector is back with every rainy season. Our studies present multidisciplinary approach that will provide insights into the cell biology of the dry season P. falciparum parasite and increase our understanding of their interactions with their hosts and environment.