Tissue printing: splenic red pulp macrophages of once-malaria infected mice are transcriptionally identical to prenatally seeded red pulp macrophages from uninfected mice.. Tissue printing: splenic red pulp macrophages of once-malaria infected mice are transcriptionally identical to prenatally seeded red pulp macrophages from uninfected mice.

Acute malaria infection with P. chabaudi obliterates embryonically seeded tissue-resident red pulp macrophages in the spleen of C57Bl/6J mice - regardless of whether the infection is mild (mosquito transmitted P. chabaudi AS - no hyperparasitaemia, no measurable clinical manifestations of disease other than low-grade anaemia) or severe (mosquito transmitted P. chabaudi AJ - acute hyperparasitaemia, severe anaemia, hypothermia and prostration). Red pulp macrophages return 100 days later, once mice cleared parasitaemia. We then flow sorted 10,000 red pulp macrophages (lineage-, autofluorescent, F4/80+, B220-, CD11bint, CD11cint) directly into Trizol, extracted total RNA and analysed their transciptome using the affymetrix mouse exon 1.0 ST array. Red pulp macrophages from mice once infected with mild AS or severe AJ P. chabaudi parasites were compared to uninfected age-matched mice. We uncover that red pulp macrophages isolated from the spleens of once-malaria infected mice are transcriptionally identical to prenatally seeded red pulp macrophages from uninfected mice. The spleen tissue niche thus imprints an identical functional profile onto these cells - regardless of their origin. Overall design: C57Bl/6J mice were bred and housed in individually ventilated cages under specific pathogen free conditions (22°C, 50% humidity) at the University of Edinburgh, UK. Malaria infections were initiated when mice were approximately 9 weeks of age by intravenous injection of 200 sporozoites (according to our previously published protocol: Spence, P.J., et al., Mosquito transmission of the rodent malaria parasite Plasmodium chabaudi. Malar J, 2012. 11: p. 407). We mosquito transmitted two distinct Plasmodium chabaudi chabaudi clones, which we obtained from the European Malaria Reagent Repository (malariaresearch.eu) at the University of Edinburgh: P. chabaudi AS (28AS11) and P. chabaudi AJ (96AJ15). Anopheles stephensi mosquitoes (strain SD500) were reared in house at the University of Edinburgh. We initiated all experimental infections with sporozoites, since we have previously shown that mosquito transmission resets expression of the large sub-telomeric multi-gene families that control parasite virulence, and in turn shapes the host immune response during the pathogenic blood-stage of malaria infection (Spence, P.J., et al., Vector transmission regulates immune control of Plasmodium virulence. Nature, 2013. 498(7453): p. 228-31). 100 days after infection, once mice had cleared parasitaemia, red pulp macrophages were flow sorted from the spleens of mice once-infected with P. chabaudi AS (mild acute infection, n = 4) or P. chabaudi AJ (severe acute infection, n = 3) and their transcriptome compared to red pulp macrophages isolated from age-matched uninfected mice (n = 5).