Diverse_outcomes_of_controlled_human_malaria_infection_originate_from_host_intrinsic_immune_variation_and_not_var_gene_switching

Falciparum malaria is clinically heterogeneous and the relative contribution of parasite and host factors in shaping disease severity remains unclear. We set out to explore the interaction between host inflammation and parasite variant surface antigen (VSA) expression, asking whether this relationship underpins the variation observed in controlled human malaria infection. We uncovered marked heterogeneity in the response of naive hosts to blood challenge with some volunteers maintaining a state of immune quiescence, others triggering interferon-stimulated inflammation and a small group showing transcriptional evidence of myeloid cell suppression. Significantly, only inflammatory volunteers experienced hallmark symptoms of clinical malaria. When we then tracked temporal changes in parasite VSA expression to ask whether variants associated with severe disease preferentially expand in naive hosts (as predicted by current theory) we found that var gene profiles were essentially unchanged after 10-days of blood-stage infection. These data therefore show that the diverse clinical outcomes of CHMI largely originate from host-intrinsic variation and there is no evidence for switching or selection of var genes in naïve hosts. This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/

Type: Transcriptome Analysis
Archiver: European Genome-Phenome Archive (EGA)

1 Dataset 1 Publication

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Dataset ID	Description	Technology	Samples
EGAD00001005790	Falciparum malaria is clinically heterogeneous and yet in most cases the risk of life-threatening disease dramatically declines after the first few infections of life because children rapidly acquire disease tolerance (resistance to severe malaria without improved control of parasite burden). Identifying the factors that determine clinical outcome in a malaria-naive host is therefore paramount to reduce malaria mortality. However, the relative contribution of disease-causing variants of the Plasmodium var gene family versus pathogenic inflammatory cytokine cascades remains fiercely debated - we sought to reconcile these conflicting arguments by studying their interaction in vivo. To this end, two human challenge models were used to reveal the parasite-host interactions that underpin variation in falciparum malaria. To capture the diversity of human immune responses, each individual was analysed independently by tracking dynamic changes in their whole blood transcriptome through time. And to uncover evidence of preferential expansion of disease-causing variants, var gene expression was tracked in vivo from the start to end of infection. In this way, we could show that group A var genes are always expressed upon liver egress but in a minority population that does not increase over 10-days of blood cycling; there is no selection of disease-causing variants in the naive host. In fact, parasites do not respond in any way to differences or changes in host environment. On the other hand, host-intrinsic variation determines the intensity of inflammation and progression to clinical malaria. And furthermore, regulation of the interferon signaling network controls host fate. These data emphasise the role of human immune decision-making in shaping course & outcome of infection. This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/ . This dataset contains all the data available for this study on 2020-01-15.	Illumina HiSeq 2500	30

Publications	Citations
Mapping immune variation and var gene switching in naive hosts infected with Plasmodium falciparum. Milne K, Ivens A, Reid AJ, Lotkowska ME, O'Toole A, Sankaranarayanan G, Munoz Sandoval D, Nahrendorf W, Regnault C, Edwards NJ, Silk SE, Payne RO, Minassian AM, Venkatraman N, Sanders MJ, Hill AV, Barrett M, Berriman M, Draper SJ, Rowe JA, Spence PJ. Elife 10: 2021 e62800	13