title: Molecular Markers of Radiation Induced Attenuation in Intrahepatic Plasmodium falciparum Parasites.
abstract: Experimental immunization with radiation attenuated sporozoites (RAS) and genetically attenuated sporozoites has proved to be a promising approach for malaria vaccine development. However, parasite biomarkers of growth attenuation and enhanced immune protection in response to radiation remain poorly understood. Here, we report on the effect of an attenuating dose of γ-irradiation (15 krad) on the Plasmodium falciparum sporozoite (PfSPZ) ultrastructure by electron microscopy, growth rate of liver stage P. falciparum in liver cell cultures, and genome-wide transcriptional profile of liver stage parasites by microarray. We find that γ-irradiation treated PfSPZ retained a normal cellular structure except that they were vacuous with a partially disrupted plasma membrane and inner membrane complex. A similar infection rate was observed by γ-irradiation-treated and untreated PfSPZ in human HCO-4 liver cells (0.47% versus 0.49%, respectively) on day 3 post-infection. In the microarray studies, cumulatively, 180 liver stage parasite genes were significantly transcriptionally altered on day 3 and/or 6 post-infection. Among the transcriptionally altered biomarkers, we identified a signature of seven candidate parasite genes that associated with functionally diverse pathways that may regulate radiation induced cell cycle arrest of the parasite within the hepatocyte. A repertoire of 14 genes associated with protein translation is transcriptionally overexpressed within the parasite by radiation. Additionally, 37 genes encode proteins expressed on the cell surface or exported into the host cell, 4 encode membrane associated transporters, and 10 encode proteins related to misfolding and stress-related protein processing. These results have significantly increased the repertoire of novel targets for 1) biomarkers of safety to define proper attenuation, 2) generating genetically attenuated parasite vaccine candidates, and 3) subunit candidate vaccines against liver stage malaria.
authors.affiliation: Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States.
authors.forename: Miranda S
authors.initials: MS
authors.lastname: Oakley
authors.affiliation: Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States.
authors.forename: Nitin
authors.initials: N
authors.lastname: Verma
authors.affiliation: Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States.
authors.forename: Hong
authors.initials: H
authors.lastname: Zheng
authors.affiliation: National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, Maryland, United States.
authors.forename: Vivek
authors.initials: V
authors.lastname: Anantharaman
authors.affiliation: Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States.
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States.
authors.forename: Yamei
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Genomics Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland, United States.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Myers
authors.affiliation: Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States.
authors.forename: Phuong Thao
authors.initials: PT
authors.lastname: Pham
authors.affiliation: Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States.
authors.forename: Babita
authors.initials: B
authors.lastname: Mahajan
authors.affiliation: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States.
authors.forename: Nirbhay
authors.initials: N
authors.lastname: Kumar
authors.affiliation: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States.
authors.forename: Davison
authors.initials: D
authors.lastname: Sangweme
authors.affiliation: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States.
authors.forename: Abhai K
authors.initials: AK
authors.lastname: Tripathi
authors.affiliation: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States.
authors.forename: Godfree
authors.initials: G
authors.lastname: Mlambo
authors.affiliation: National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, Maryland, United States.
authors.forename: L
authors.initials: L
authors.lastname: Aravind
authors.affiliation: Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States.
authors.forename: Sanjai
authors.initials: S
authors.lastname: Kumar
mesh_terms: D000818:Animals; D000852:Anopheles; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D005260:Female; D005720:Gamma Rays; D005786:Gene Expression Regulation / Q000528:radiation effects*; D006801:Humans; D008099:Liver / Q000378:metabolism* / Q000469:parasitology; D017780:Malaria Vaccines / Q000378:metabolism*; D016778:Malaria, Falciparum / Q000378:metabolism / Q000517:prevention & control; D010963:Plasmodium falciparum / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism*; D034101:Sporozoites / Q000378:metabolism*; D014613:Vaccines, Attenuated / Q000378:metabolism
chemical_list: D015415:Biomarkers; D017780:Malaria Vaccines; D015800:Protozoan Proteins; D014613:Vaccines, Attenuated