Plasmodium vivax gametocytes in the bone marrow of an acute malaria patient and changes in the erythroid miRNA profile

Background: Human studies of Plasmodium vivax in the bone marrow are scarce even though its presence in this tissue was first noticed more than a century ago. Material and Methods: Here, we examined bone marrow aspirates taken from a patient with P. vivax clinical malaria on admission (13,280 parasites/μL), before antimalarial treatment, and 42 days after treatment. Results: On admission, parasitemia was similar in peripheral blood and bone marrow; yet, rings and gametocytes were significantly more abundant in the bone marrow. Furthermore, morphological analysis revealed signs of dyserythropoiesis and inefficient erythropoiesis. Last, transcriptional analysis of RNA extracted from marrow erythroid precursors cells (CD71+) revealed significant changes in global small RNA profiles during infection compared to convalescence. Analysis of miRNAs related to erythropoiesis showed a distinct series of differentially expressed miRNAs during P. vivax infection in this patient. Conclusion: All together, these results provide the first quantification of parasite stages found in the bone marrow of a patient and demonstrate that its presence influences transcriptional changes of miRNAs involved in erythropoiesis.