Plasmodium vivax Duffy binding protein: baseline antibody responses and parasite polymorphisms in a well-consolidated settlement of the Amazon Region.
OBJECTIVE
To investigate risk factors associated with the acquisition of antibodies against Plasmodium vivax Duffy binding protein (PvDBP) - a leading malaria vaccine candidate - in a well-consolidated agricultural settlement of the Brazilian Amazon Region and to determine the sequence diversity of the PvDBP ligand domain (DBP(II)) within the local malaria parasite population.


METHODS
Demographic, epidemiological and clinical data were collected from 541 volunteers using a structured questionnaire. Malaria parasites were detected by conventional microscopy and PCR, and blood collection was used for antibody assays and molecular characterisation of DBP(II).


RESULTS
The frequency of malaria infection was 7% (6% for P. vivax and 1% for P. falciparum), with malaria cases clustered near mosquito breeding sites. Nearly 50% of settlers had anti-PvDBP IgG antibodies, as detected by enzyme-linked immunosorbent assay (ELISA) with subject's age being the only strong predictor of seropositivity to PvDBP. Unexpectedly, low levels of DBP(II) diversity were found within the local malaria parasites, suggesting the existence of low gene flow between P. vivax populations, probably due to the relative isolation of the studied settlement.


CONCLUSIONS
The recognition of PvDBP by a significant proportion of the community, associated with low levels of DBP(II) diversity among local P. vivax, reinforces the variety of malaria transmission patterns in communities from frontier settlements. Such studies should provide baseline information for antimalarial vaccines now in development.
Laboratório de Malária, Centro de Pesquisas René Rachou/Fiocruz, Belo Horizonte-MG, Brazil.
Flora S
FS
Kano
Bruno A M
BA
Sanchez
Tais N
TN
Sousa
Michaelis L
ML
Tang
Jéssica
J
Saliba
Fernando M
FM
Oliveira
Paulo A
PA
Nogueira
Alessandra Q
AQ
Gonçalves
Cor J F
CJ
Fontes
Irene S
IS
Soares
Cristiana F A
CF
Brito
Roberto S
RS
Rocha
Luzia H
LH
Carvalho
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000913:Antibodies, Protozoan / Q000276:immunology; D000953:Antigens, Protozoan / Q000235:genetics* / Q000276:immunology*; D001938:Brazil / Q000453:epidemiology; D002648:Child; D003430:Cross-Sectional Studies; D016054:DNA, Protozoan; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D014644:Genetic Variation; D006801:Humans; D007199:Indians, South American; D016780:Malaria, Vivax / Q000097:blood / Q000453:epidemiology / Q000635:transmission; D008297:Male; D010966:Plasmodium vivax / Q000235:genetics* / Q000276:immunology*; D011110:Polymorphism, Genetic; D015995:Prevalence; D015800:Protozoan Proteins / Q000235:genetics* / Q000276:immunology*; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000276:immunology*; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D012959:Socioeconomic Factors; D055815:Young Adult
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D016054:DNA, Protozoan; C066001:Duffy antigen binding protein, Plasmodium; D015800:Protozoan Proteins; D011956:Receptors, Cell Surface