B cell epitope mapping and characterization of naturally acquired antibodies to the Plasmodium vivax Merozoite Surface Protein-3α (PvMSP-3 α) in malaria exposed individuals from Brazilian Amazon

Laboratory of Immunoparasitology, Institute Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil.
Vaccine (Impact Factor: 3.62). 02/2011; 29(9):1801-11. DOI: 10.1016/j.vaccine.2010.12.099
Source: PubMed


The Plasmodium vivax Merozoite Surface Protein-3α (PvMSP-3α) is considered as a potential vaccine candidate. However, the detailed investigations of the type of immune responses induced in naturally exposed populations are necessary. Therefore, we aim to characterize the naturally induced antibody to PvMSP-3α in 282 individuals with different levels of exposure to malaria infections residents in Brazilian Amazon. PvMSP3 specific antibodies (IgA, IgG and IgG subclass) to five recombinant proteins and the epitope mapping by Spot-synthesis technique to full-protein sequence of amino acids (15aa sequence with overlapping sequence of 9aa) were performed. Our results indicates that PvMSP3 is highly immunogenic in naturally exposed populations, where 78% of studied individuals present IgG immune response against the full-length recombinant protein (PVMSP3-FL) and IgG subclass profile was similar to all five recombinant proteins studied with a high predominance of IgG1 and IgG3. We also observe that IgG and subclass levels against PvMSP3 are associated with malaria exposure. The PvMSP3 epitope mapping by Spot-synthesis shows a natural recognition of at least 15 antigenic determinants, located mainly in the two blocks of repeats, confirming the high immunogenicity of this region. In conclusion, PvMSP-3α is immunogenic in naturally exposed individuals to malaria infections and that antibodies to PvMSP3 are induced to several B cell epitopes. The presence of PvMSP3 cytophilic antibodies (IgG1 and IgG3), suggests that this mechanism could also occur in P. vivax.

Download full-text


Available from: Josué da Costa Lima-Junior, Oct 06, 2015
1 Follower
50 Reads
  • Source
    • "The function of each protein is unknown, and naturally acquired immune responses have so far only been studied against PvMSP3.10 (PvMSP3-α) [26]–[28], leaving much to be understood about the biological and immunogenic role this family of proteins has in terms of immunomodulation and protection. Finally, just as pvmsp3-α and pvmsp3-β have become genetic markers of diversity and tools for studying population genetics of P. vivax [213–23,53–60], other members of the family may be similarly suited. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Three members of the Plasmodium vivax merozoite surface protein-3 (PvMSP3) family (PvMSP3-α, PvMSP3-β and PvMSP3-γ) were initially characterized and later shown to be part of a larger highly diverse family, encoded by a cluster of genes arranged head-to-tail in chromosome 10. PvMSP3-α and PvMSP3-β have become genetic markers in epidemiological studies, and are being evaluated as vaccine candidates. This research investigates the gene and protein expression of the entire family and pertinent implications. A 60 kb multigene locus from chromosome 10 in P. vivax (Salvador 1 strain) was studied to classify the number of pvmsp3 genes present, and compare their transcription, translation and protein localization patterns during blood-stage development. Eleven pvmsp3 paralogs encode an N-terminal NLRNG signature motif, a central domain containing repeated variable heptad sequences, and conserved hydrophilic C-terminal features. One additional ORF in the locus lacks these features and was excluded as a member of the family. Transcripts representing all eleven pvmsp3 genes were detected in trophozoite- and schizont-stage RNA. Quantitative immunoblots using schizont-stage extracts and antibodies specific for each PvMSP3 protein demonstrated that all but PvMSP3.11 could be detected. Homologs were also detected by immunoblot in the closely related simian species, P. cynomolgi and P. knowlesi. Immunofluorescence assays confirmed that eight of the PvMSP3s are present in mature schizonts. Uniquely, PvMSP3.7 was expressed exclusively at the apical end of merozoites. Specific proteins were detected representing the expression of 10 out of 11 genes confirmed as members of the pvmsp3 family. Eight PvMSP3s were visualized surrounding merozoites. In contrast, PvMSP3.7 was detected at the apical end of the merozoites. Pvmsp3.11 transcripts were present, though no corresponding protein was detected. PvMSP3 functions remain unknown. The ten expressed PvMSP3s are predicted to have unique and complementary functions in merozoite biology.
    PLoS ONE 05/2013; 8(5):e63888. DOI:10.1371/journal.pone.0063888 · 3.23 Impact Factor
  • Source
    • "We demonstrated that the frequencies of individuals with IgG antibodies to PvMSP-3α and at least one of the three recombinant proteins representing PvMSP-3β were relatively high (68.2% and 79.1%, respectively). For PvMSP-3α, these findings confirm two recent studies performed in distinct endemic areas of the Brazilian Amazon, where 78% [19] and 58.4% [20] of individuals presented IgG antibodies to this protein. "
    [Show abstract] [Hide abstract]
    ABSTRACT: A recent clinical trial in African children demonstrated the potential utility of merozoite surface protein (MSP)-3 as a vaccine against malaria. The present study evaluated the use of MSP-3 (PvMSP-3) as a target antigen in vaccine formulations against malaria caused by . Recombinant proteins representing MSP-3α and MSP-3β of were expressed as soluble histidine-tagged bacterial fusions. Antigenicity during natural infection was evaluated by detecting specific antibodies using sera from individuals living in endemic areas of Brazil. A large proportion of infected individuals presented IgG antibodies to PvMSP-3α (68.2%) and at least 1 recombinant protein representing PvMSP-3β (79.1%). In spite of the large responder frequency, reactivity to both antigens was significantly lower than was observed for the immunodominant epitope present on the 19-kDa C-terminal region of PvMSP-1. Immunogenicity of the recombinant proteins was studied in mice in the absence or presence of different adjuvant formulations. PvMSP-3β, but not PvMSP-3α, induced a TLR4-independent humoral immune response in the absence of any adjuvant formulation. The immunogenicity of the recombinant antigens were also tested in formulations containing different adjuvants (Alum, flagellin, CpG, Quil A,TiterMax® and incomplete Freunds adjuvant) and combinations of two adjuvants (Alum plus flagellin, and CpG plus flagellin). Recombinant PvMSP-3α and PvMSP-3β elicited higher antibody titers capable of recognizing infected erythrocytes harvested from malaria patients. Our results confirm that MSP-3 antigens are immunogenic during natural infection, and the corresponding recombinant proteins may be useful in elucidating their vaccine potential.
    PLoS ONE 02/2013; 8(2):e56061. DOI:10.1371/journal.pone.0056061 · 3.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study describes a bioinformatics approach designed to identify Plasmodium vivax proteins potentially involved in reticulocyte invasion. Specifically, different protein training sets were built and tuned based on different biological parameters, such as experimental evidence of secretion and/or involvement in invasion-related processes. A profile-based sequence method supported by hidden Markov models (HMMs) was then used to build classifiers to search for biologically-related proteins. The transcriptional profile of the P. vivax intra-erythrocyte developmental cycle was then screened using these classifiers. A bioinformatics methodology for identifying potentially secreted P. vivax proteins was designed using sequence redundancy reduction and probabilistic profiles. This methodology led to identifying a set of 45 proteins that are potentially secreted during the P. vivax intra-erythrocyte development cycle and could be involved in cell invasion. Thirteen of the 45 proteins have already been described as vaccine candidates; there is experimental evidence of protein expression for 7 of the 32 remaining ones, while no previous studies of expression, function or immunology have been carried out for the additional 25. The results support the idea that probabilistic techniques like profile HMMs improve similarity searches. Also, different adjustments such as sequence redundancy reduction using Pisces or Cd-Hit allowed data clustering based on rational reproducible measurements. This kind of approach for selecting proteins with specific functions is highly important for supporting large-scale analyses that could aid in the identification of genes encoding potential new target antigens for vaccine development and drug design. The present study has led to targeting 32 proteins for further testing regarding their ability to induce protective immune responses against P. vivax malaria.
    PLoS ONE 10/2011; 6(10):e25189. DOI:10.1371/journal.pone.0025189 · 3.23 Impact Factor
Show more