To die, to sleep: Biology and evolution of dormancy in avian malaria parasites (HAMLET)

Avian malaria (Plasmodium sp) parasites have been at the forefront of research into bird conservation since the accidental introduction of P. relictum to Hawaii in the early 20th century, which resulted in the decline and extinction of several native bird species. Due to the predicted increase in the occurrence, distribution and intensity of avian malaria associated to the ongoing climate change, avian Plasmodium parasites represent one of the main threats to bird biodiversity and conservation. One of the keys to the invasion success of avian malaria parasites is their ability to produce dormant stages. Dormancy describes a series of reversible physiological adjustments that enhance survival in temporarily hostile environments. Dormant avian malaria stages hide from the bird’s immune system in deep tissues (liver, lungs, brain…) for long periods of time (months or years). When conditions improve, these dormant stages ‘wake up’ from their quiescent stage and recolonize the blood (i.e., they relapse), where they can resume their multiplication and transmission to new hosts. Dormants have crucial epidemiological and evolutionary implications because: (i) they serve as a cryptic reservoirs of infection, and (ii) they also serve as reservoirs of parasite genetic diversity, ensuring genetic recombination between unrelated parasites in areas of low transmission. Despite this, the dormant stages of avian malaria are, unquestionably, the largest black box in the avian malaria cycle. WP 1 will use state of the art single cell and spatial transcriptomics to gain knowledge on the biology of both the dormant stages of avian malaria parasites and their host-cell environment. WP 2  will use novel experimental approaches to determine whether relapses are a plastic response of the parasite to environmental triggers (mosquito bites, co-infections, stress-related signals). WP 3 will obtain avian malaria samples from field sites at different latitudes which, combined with theoretical models, will allow to establish whether variability in the environment’s seasonality affects the evolution of dormancy. This study will extend the comparative analysis of dormancy beyond human and simian malaria parasites, and will provide key insights into the degree of conservation of dormancy pathways and into the selective pressures that have shaped the evolution of this trait and its variation in natural populations.

Project details

Basic Science

Dec 2023 — Dec 2027

$878,130

France