Latent liver stages termed hypnozoites cause relapsing
Plasmodium vivax malaria infection and represent a major obstacle in the goal of
malaria elimination. Hypnozoites are clinically undetectable, and presently, there are no
biomarkers of this persistent parasite reservoir in the human liver. Here, we have identified parasite and human
proteins associated with extracellular vesicles (EVs) secreted from in vivo
infections exclusively containing hypnozoites. We used P. vivax-infected human liver-chimeric (huHEP) FRG KO mice treated with the schizonticidal experimental
drug MMV048 as hypnozoite
infection model. Immunofluorescence-based quantification of P. vivax liver forms showed that
MMV048 removed schizonts from chimeric mice livers. Proteomic analysis of EVs derived from FRG huHEP mice showed that human EV cargo from infected FRG huHEP mice contain
inflammation markers associated with active schizont replication and identified 66 P. vivax
proteins. To identify hypnozoite-specific
proteins associated with EVs, we mined the
proteome data from MMV048-treated mice and performed an analysis involving intragroup and intergroup comparisons across all experimental conditions followed by a
peptide compatibility analysis with predicted spectra to warrant robust identification. Only one
protein fulfilled this stringent top-down selection, a putative
filamin domain-containing
protein. This study sets the stage to unveil
biological features of human liver
infections and identify
biomarkers of hypnozoite
infection associated with EVs.