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Infection and Immunity, November 1999, p. 5906-5916, Vol. 67, No. 11
Department of Parasitology,
Received 26 May 1999/Accepted 26 August 1999
The polymorphic merozoite surface protein (MSP-1) of
Plasmodium falciparum is a major asexual blood-stage
malaria vaccine candidate. The impact of allelic diversity on
recognition of MSP-1 during the immune response remains to be
investigated in areas of hypoendemicity such as the Brazilian Amazon
region. In this study, PCR was used to type variable regions, blocks 2, 4, and 10, of the msp-1 gene and to characterize major gene
types (unique combinations of allelic types in variable blocks) in
P. falciparum isolates collected across the Amazon basin
over a period of 12 years. Twelve of the 24 possible gene types were
found among 181 isolates, and 68 (38%) of them had more than one gene
type. Temporal, but not spatial, variation was found in the
distribution of MSP-1 gene types in the Amazon. Interestingly, some
gene types occurred more frequently than expected from random
assortment of allelic types in different blocks, as previously found in
other areas of endemicity. We also compared the antibody recognition of
polymorphic (block 2), dimorphic (block 6), and conserved (block 3)
regions of MSP-1 in Amazonian malaria patients and clinically immune
Africans, using a panel of recombinant peptides. Results were
summarized as follows. (i) All blocks were targeted by naturally
acquired cytophilic antibodies of the subclasses IgG1 and IgG3, but the balance between IgG1 and IgG3 depended on the subjects' cumulative exposure to malaria. (ii) The balance between IgG1 and IgG3 subclasses and the duration of antibody responses differed in relation to distinct
MSP-1 peptides. (iii) Antibody responses to variable blocks 2 and 6 were predominantly type specific, but variant-specific antibodies that
target isolate-specific repetitive motifs within block 2 were more
frequent in Amazonian patients than in previously studied African populations.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Allelic Diversity and Antibody Recognition of
Plasmodium falciparum Merozoite Surface Protein 1 during
Hypoendemic Malaria Transmission in the Brazilian Amazon
Region
*
Corresponding author. Mailing address: Departamento de
Doenças Infecciosas e Parasitárias, Laboratório de
Parasitologia Molecular, Faculdade de Medicina de São José
do Rio Preto, Av. Brigadeiro Faria Lima, 5416, 15090-000, São
José do Rio Preto (SP), Brazil. Phone and Fax: (55) (17)
234-1994. E-mail: muferrei{at}hotmail.com.
Infection and Immunity, November 1999, p. 5906-5916, Vol. 67, No. 11
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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