Abstract
Duffy antigen is the receptor used by Plasmodium vivax to invade erythrocytes. Consequently, individuals lacking Duffy antigen [Fy(-)] do not develop blood-stage infections. We hypothesized that naturally exposed Fy(-) humans may develop immune responses mainly to pre-erythrocytic stages and could be used to study acquired immunity to P. vivax and to identify liver-stage antigens. We report here that antibody and IFN-γ responses to known sporozoite antigens were significantly induced by natural exposure in Fy(-) humans, whereas responses to blood-stage antigens were significantly induced in Fy(+) humans. IFN-γ responses to sporozoite antigens were lower in Fy(+) than in Fy(-) humans, indicating that in Fy(+) humans blood-stage infections may have suppressed T cell responses to pre-erythrocytic stages. We evaluated the immune responses to 18 novel P. vivax homologs of P. falciparum sporozoite proteins identified from the P. vivax genome sequence. Eight proteins recalled IFN-γ responses in P. vivax-exposed but not in unexposed individuals. Of these, 3 antigens elicited IFN-γ responses in Fy(-) but not in Fy(+) individuals. These results suggest that differential immune responses observed in naturally exposed Fy(-) and Fy(+) individuals can be exploited to identify P. vivax stage-specific antigens.
Original language | English (US) |
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Pages (from-to) | 1859-1868 |
Number of pages | 10 |
Journal | European Journal of Immunology |
Volume | 35 |
Issue number | 6 |
DOIs | |
State | Published - Jun 2005 |
Keywords
- Acquired immunity
- Duffy antigen
- IFN-γ
- Plasmodium vivax
- Pre-erythrocytic stage
ASJC Scopus subject areas
- Immunology and Allergy
- Immunology