Table 3. Examples of potential antigens for use in sero-surveillance.
| Antigens present in Plasmodium falciparum and P. vivaxa | ||||||||
|---|---|---|---|---|---|---|---|---|
| AMA1 | CSP | MSP119 | MSP3 | |||||
| Identity between Pf and Pv sequencesb | 51% (Ecto-domain) | 25% | 45% | 20% (C-terminus)c | ||||
| Polymorphisms | >10% of ecto-domain amino acids in PfAMA1 and PvAMA1 are polymorphic. Antibodies also target cross-reactive epitopes | Substantial polymorphism. Relatively conserved N and C-terminal domains flank the highly polymorphic central repeat regions. |
Limited polymorphism. Pf-MSP119 has 4 polymorphic residues |
Substantial polymorphism: PfMSP3 has central polymorphic domain. PvMSP3α has length and sequence polymorphism. |
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| Antibody cross-reactivity between species | Some cross-reactivity detected with antibodies generated in animals (unpublished data) | Unknown | Unknown | Unknown | ||||
| Comments | 1. PfAMA1 and PvAMA1 are vaccine candidates 2. Potential value in sero-surveillance already demonstrated |
1. Leading vaccine candidate, which may preclude its use in sero-surveillance in the future 2. Potential in sero- surveillance has been demonstrated |
Potential in sero-surveillance has already been demonstrated | 1. Shown to be immunogenic in many different populations and settings 2. PfMSP3 is currently in vaccine trials |
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aMany immunogenic proteins that could be used in sero-surveillance are present in both species.
bComparison of P. falciparum 3D7 isolate with P. vivax Sal1 isolate.
cC-terminus has the most conservation in sequence between species. AMA1, apical membrane protein 1; CSP, circumsporozoite protein; DBP, Duffy-binding protein; EBA175, erythrocyte binding antigen 175; MSP, merozoite surface protein; PfRH2, P. falciparum reticulocyte-binding homologue; RBP1, reticulocyte-binding protein 1.