Abstract
For 50 years since their discovery, the malaria parasite liver stages (LS) have been difficult to analyze, impeding their utilization as a critical target for antiinfection vaccines and drugs. We have undertaken a comprehensive transcriptome analysis in combination with a proteomic survey of LS. Green fluorescent protein-tagged Plasmodium yoelii (PyGFP) was used to efficiently isolate LS-infected hepatocytes from the rodent host. Genome-wide LS gene expression was profiled and compared with other parasite life cycle stages. The analysis revealed approximately 2,000 genes active during LS development, and proteomic analysis identified 816 proteins. A subset of proteins appeared to be expressed in LS only. The data revealed exported parasite proteins and LS metabolic pathways including expression of FASII pathway enzymes. The FASII inhibitor hexachlorophene and the antibiotics, tetracycline and rifampicin, that target the apicoplast inhibited LS development, identifying FASII and other pathways localized in the apicoplast as potential drug targets to prevent malaria infection.
Highlights
liver stages (LS)-infected hepatocytes were obtained directly from infected mice at 24 h postinfection, when the majority of LS parasites are at a small early schizont stage and have undergone two to four rounds of nuclear division (LS24); at 40 h pi, when the majority of LS parasites are at large late schizont stage and have undergone up to 13 rounds of nuclear division (LS40); and at 50 h pi, when the majority of LS parasites have commenced merozoite formation (LS50) [Fig. 1A; supporting information (SI) Fig. 5]
The gene expression of LS was compared with two mosquito stages and intraerythrocytic stages
The gene expression profiles of the three LS developmental time points were more similar to Author contributions: A.S.T. and X.P. contributed to this work; A.S.T., X.P., and S.H.I.K. designed research; A.S.T., R.F.D., Y.O., H.S.-R., and N.C. performed research; T.M.D. and L.B. contributed new reagents/analytic tools; A.S.T. and X.P. analyzed data; and A.S.T., X.P., and S.H.I.K. wrote the paper
Summary
We used an oligonucleotide (65-mer) microarray, designed based on the annotated ORFs of the rodent malaria parasite P. yoelii [9], to analyze gene expression at three time points of LS development in vivo. LS up-regulated genes in each of the developmental stages examined were clustered by using a hierarchical algorithm (Fig. 1C) Organized in this manner, a developmental series of gene expression patterns that varied mainly in the timing and the duration for which the gene was active were discerned. The first cluster (I) included LS genes mainly up-regulated in LS24 compared with LS40 and LS50, but that were expressed in the mosquito and erythrocytic stages. The availability of isolated LS-infected hepatocytes enabled proteomic analysis of the Plasmodium parasite in the liver host environment in vivo. There are 104 additional proteins, which were identified by searching against the P. berghei sequence database, but their P. yoelii orthologs were not mapped in the study
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
