A conservedPlasmodiumprotein that localizes to liver stage nuclei is critical for late liver stage development

Abstract

Malaria, the disease caused byPlasmodiumparasites, causes significant mortality and morbidity. Whole parasite vaccination with pre-erythrocytic parasite stages, attenuated through sporozoite irradiation or chemo-attenuation, confers sterilizing immunity against subsequent parasite infection. This provides a rationale for the creation of whole parasite vaccines that are attenuated using gene editing. Here, we report on the creation of a novel genetically attenuated parasite (GAP) by the deletion ofPlasmodium LINUP, encoding a liver stage nuclear protein. Epitope-tagging of LINUP in the rodent malaria parasitePlasmodium yoeliishowed LINUP expression exclusively in liver stage nuclei after the onset of exo-erythrocytic schizogony.P. yoeliiparasites with a gene deletion ofLINUP(linup—) suffered an exclusive liver stage phenotype with developmental arrested late in exo-erythrocytic schizogony. Liver stages showed incomplete segregation of nuclei and, mitochondria and apicoplast. These cellular perturbations caused a defect in exo-erythrocytic merozoite formation and a concomitant severe attenuation of liver stage-to-blood stage transition.LINUPgene deletion inPlasmodium falciparumalso caused a severe defect in late liver stage differentiation. Importantly,P. falciparum linup—liver stages showed a severe defect in parasite transitioning from liver stage to viable blood stage infection. These results suggest thatP. falciparum LINUPis a useful target for late liver stage attenuation and an additional gene deletion that can be incorporated into a late liver stage-arresting replication competent whole parasite vaccine.

Sporozoite immunization: innovative translational science to support the fight against malaria

“…The immunizations induced significantly higher protective immune responses compared to those achieved using similar mosquito-bite immunization with early arresting GA1 parasites [ 147 ]. However, because the rodent malaria plasmei2 − LARC GAP showed occasional breakthrough infection when high Py sporozoite doses were injected, the Kappe lab at SCRI decided to introduce a second deletion, of a gene called LINUP (liver stage nuclear protein) [ 221 ]. The rodent malaria Py dual gene deletion ( plasmei2 − / linup − ) double knockout GAP showed no break-through infection in mice (Goswami, unpublished) and the Pf plasmei2 − /linup − double knockout GAP showed no break-through infections in a humanized mouse model (Goswami, unpublished).…”