Antibodies to Plasmodium falciparum and Plasmodium vivax merozoite surface protein 5 in Indonesia: species-specific and cross-reactive responses.
BACKGROUND
Merozoite surface protein (MSP) 5 is a candidate antigen for a malaria vaccine. In cross-sectional and longitudinal studies, we measured MSP5 antibody responses in Papuans with acute Plasmodium falciparum malaria, Plasmodium vivax malaria, and mixed P. falciparum and P. vivax malaria and in those with past exposure.


METHODS
Enzyme-linked immunosorbant assay (ELISA) was used to quantitate antibody responses to P. falciparum MSP5 (PfMSP5) and P. vivax MSP5 (PvMSP5) in 82 subjects with P. falciparum infection, 86 subjects with P. vivax infection, 85 subjects with mixed infection, and 87 asymptomatic individuals. Longitudinal responses through day 28 were tested in 20 persons. Cross-reactivity was tested by competition ELISA.


RESULTS
PfMSP5 or PvMSP5 immunoglobulin (Ig)Gwas detected in 39%-52% of subjects, and IgM was detected in 44%-72%. IgG responses were distributed equally between IgG3 and IgG1 for PfMSP5 but were predominantly IgG3 for PvMSP5. Although IgG responses were generally specific for PfMSP5 or PvMSP5, cross-species reactivity was found in 7 of 107 dual-positive responders. No significant difference was seen in the magnitude, frequency, or subclass of PfMSP5 or PvMSP5 IgG antibodies between groups. There was no significant association between antibody responses and therapeutic response.


CONCLUSIONS
PfMSP5 and PvMSP5 were frequently recognized by short-lived, species-specific antibodies. Although infrequent, the cross-reactive MSP5 antibodies indicate that an appropriately formulated vaccine may elicit and/or enhance cross-species recognition, which may be very useful in areas where both parasites are endemic.
Woodberry
Tonia
T
International Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Australia.
Minigo
Gabriela
G
Piera
Kim A
KA
Hanley
Jennifer C
JC
de Silva
Harini D
HD
Salwati
Ervi
E
Kenangalem
Enny
E
Tjitra
Emiliana
E
Coppel
Ross L
RL
Price
Ric N
RN
Anstey
Nicholas M
NM
Plebanski
Magdalena
M
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology*; D000962:Antimalarials / Q000627:therapeutic use; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D007214:Indonesia; D016778:Malaria, Falciparum / Q000517:prevention & control; D016780:Malaria, Vivax / Q000517:prevention & control; D008565:Membrane Proteins / Q000276:immunology*; D018512:Parasitemia / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology*; D010966:Plasmodium vivax / Q000276:immunology*; D013045:Species Specificity
D000913:Antibodies, Protozoan; D000962:Antimalarials; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008565:Membrane Proteins; C114957:merozoite surface protein 5