Document Detail


Extreme CD8 T cell requirements for anti-malarial liver-stage immunity following immunization with radiation attenuated sporozoites.
MedLine Citation:
PMID:  20657824     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Radiation-attenuated Plasmodium sporozoites (RAS) are the only vaccine shown to induce sterilizing protection against malaria in both humans and rodents. Importantly, these "whole-parasite" vaccines are currently under evaluation in human clinical trials. Studies with inbred mice reveal that RAS-induced CD8 T cells targeting liver-stage parasites are critical for protection. However, the paucity of defined T cell epitopes for these parasites has precluded precise understanding of the specific characteristics of RAS-induced protective CD8 T cell responses. Thus, it is not known whether quantitative or qualitative differences in RAS-induced CD8 T cell responses underlie the relative resistance or susceptibility of immune inbred mice to sporozoite challenge. Moreover, whether extraordinarily large CD8 T cell responses are generated and required for protection following RAS immunization, as has been described for CD8 T cell responses following single-antigen subunit vaccination, remains unknown. Here, we used surrogate T cell activation markers to identify and track whole-parasite, RAS-vaccine-induced effector and memory CD8 T cell responses. Our data show that the differential susceptibility of RAS-immune inbred mouse strains to Plasmodium berghei or P. yoelii sporozoite challenge does not result from host- or parasite-specific decreases in the CD8 T cell response. Moreover, the surrogate activation marker approach allowed us for the first time to evaluate CD8 T cell responses and protective immunity following RAS-immunization in outbred hosts. Importantly, we show that compared to a protective subunit vaccine that elicits a CD8 T cell response to a single epitope, diversifying the targeted antigens through whole-parasite RAS immunization only minimally, if at all, reduced the numerical requirements for memory CD8 T cell-mediated protection. Thus, our studies reveal that extremely high frequencies of RAS-induced memory CD8 T cells are required, but may not suffice, for sterilizing anti-Plasmodial immunity. These data provide new insights into protective CD8 T cell responses elicited by RAS-immunization in genetically diverse hosts, information with relevance to developing attenuated whole-parasite vaccines.
Authors:
Nathan W Schmidt; Noah S Butler; Vladimir P Badovinac; John T Harty
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-07-15
Journal Detail:
Title:  PLoS pathogens     Volume:  6     ISSN:  1553-7374     ISO Abbreviation:  PLoS Pathog.     Publication Date:  2010  
Date Detail:
Created Date:  2010-07-26     Completed Date:  2010-10-19     Revised Date:  2011-01-27    
Medline Journal Info:
Nlm Unique ID:  101238921     Medline TA:  PLoS Pathog     Country:  United States    
Other Details:
Languages:  eng     Pagination:  e1000998     Citation Subset:  IM    
Affiliation:
Department of Microbiology, University of Iowa, Iowa City, Iowa, United States of America.
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MeSH Terms
Descriptor/Qualifier:
Animals
Antimalarials / immunology
CD8-Positive T-Lymphocytes / immunology*
Immunity
Immunization*
Immunologic Memory
Liver / immunology,  parasitology*
Malaria Vaccines / administration & dosage,  immunology*
Mice
Sporozoites / immunology*,  radiation effects
Vaccines, Attenuated / immunology
Grant Support
ID/Acronym/Agency:
1-F32-AI084329/AI/NIAID NIH HHS; 5-T32-AI0726024/AI/NIAID NIH HHS; AI83286/AI/NIAID NIH HHS; R01 AI085515-02/AI/NIAID NIH HHS
Chemical
Reg. No./Substance:
0/Antimalarials; 0/Malaria Vaccines; 0/Vaccines, Attenuated
Comments/Corrections

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