Project description:Sterile immunity to Plasmodium falciparum infection can be induced experimentally in humans after few exposures. An example is the induction of immunity using whole parasites by exposure of malaria-naive volunteers to infectious mosquito bites while using chloroquine prophylaxis (CPS immunization). Chloroquine kills blood-stage parasites but leaves liver-stage parasites unaffected, thereby exposing the liver-stage and early blood-stage antigens to the immune system. Upon subsequent challenge, volunteers are completely protected from infection, but protective efficacy decreases when fewer infectious mosquito bites are used for CPS immunization. Efforts to understand the mechanisms of this immunity, and how it differs from naturally-acquired immunity, may provide critical insights that could aid malaria vaccine development. In this pilot study, transcriptomic features are derived from blood samples collected before and after challenge with infectious mosquito bites. 12 samples; paired pre- and post-challenge for 5 individuals, plus two controls
Project description:Sterile immunity to Plasmodium falciparum infection can be induced experimentally in humans after few exposures. An example is the induction of immunity using whole parasites by exposure of malaria-naive volunteers to infectious mosquito bites while using chloroquine prophylaxis (CPS immunization). Chloroquine kills blood-stage parasites but leaves liver-stage parasites unaffected, thereby exposing the liver-stage and early blood-stage antigens to the immune system. Upon subsequent challenge, volunteers are completely protected from infection, but protective efficacy decreases when fewer infectious mosquito bites are used for CPS immunization. Efforts to understand the mechanisms of this immunity, and how it differs from naturally-acquired immunity, may provide critical insights that could aid malaria vaccine development. In this pilot study, transcriptomic features are derived from blood samples collected before and after challenge with infectious mosquito bites.
Project description:Immunity to malaria can be acquired through natural exposure to Plasmodium falciparum (Pf), but only after years of repeated infections. Typically, this immunity is acquired by adolescence and confers protection against disease, but not Pf infection per se. Efforts to understand the mechanisms of this immunity are integral to the development of a vaccine that would mimic the induction of adult immunity in children. The current study applies transcriptomic analyses to a cohort from the rural village of Kalifabougou, Mali, where Pf transmission is intense and seasonal. Signatures that correlate with protection from malaria may yield new hypotheses regarding the biological mechanisms through which malaria immunity is induced by natural Pf infection. The resulting datasets will be of considerable value in the urgent worldwide effort to develop a malaria vaccine that could prevent more than a million deaths annually. 108 samples; paired pre- and post-challenge for 54 individuals 198 samples; paired pre- and post-challenge for 99 individuals
Project description:Using genome-wide expression profiles from persons either experimentally challenged with malaria-infected mosquitoes or naturally-infected with Plasmodium falciparum malaria, we present details of the transcriptional changes that occur with infection and that are either commonly shared between subjects with pre-symptomatic and clinically apparent malaria or that distinguish these two groups. Our findings confirm and extend aspects of the earliest responses to malaria infection at the molecular level and which may be informative in elucidating how innate and adaptive immune responses may be modulated in different stages of infection. Experiment Overall Design: Compared samples from patients with naturally acquired malaria infection to those from volunteers in a challenge model vaccine trial.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:Immunity to malaria can be acquired through natural exposure to Plasmodium falciparum (Pf), but only after years of repeated infections. Typically, this immunity is acquired by adolescence and confers protection against disease, but not Pf infection per se. Efforts to understand the mechanisms of this immunity are integral to the development of a vaccine that would mimic the induction of adult immunity in children. The current study applies transcriptomic analyses to a cohort from the rural village of Kalifabougou, Mali, where Pf transmission is intense and seasonal. Signatures that correlate with protection from malaria may yield new hypotheses regarding the biological mechanisms through which malaria immunity is induced by natural Pf infection. The resulting datasets will be of considerable value in the urgent worldwide effort to develop a malaria vaccine that could prevent more than a million deaths annually.