Article

A Central Role for P48/45 in Malaria Parasite Male Gamete Fertility

Laboratory for Parasitology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
Cell (Impact Factor: 33.12). 02/2001; 104(1):153-64. DOI: 10.1016/S0092-8674(01)00199-4
Source: PubMed

ABSTRACT Fertilization and zygote development are obligate features of the malaria parasite life cycle and occur during parasite transmission to mosquitoes. The surface protein PFS48/45 is expressed by male and female gametes of Plasmodium falciparum and PFS48/45 antibodies prevent zygote development and transmission. Here, gene disruption was used to show that Pfs48/45 and the ortholog Pbs48/45 from a rodent malaria parasite P. berghei play a conserved and important role in fertilization. p48/45- parasites had a reduced capacity to produce oocysts in mosquitoes due to greatly reduced zygote formation. Unexpectedly, only male gamete fertility of p48/45- parasites was affected, failing to penetrate otherwise fertile female gametes. P48/45 is shown to be a surface protein of malaria parasites with a demonstrable role in fertilization.

Download full-text

Full-text

Available from: Joanna A M Braks, Mar 10, 2015
0 Followers
 · 
108 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Since the genome of Plasmodium vivax was sequenced, few proteins have been characterized as highly immunogenic and candidates for inclusion in a vivax malaria vaccine. The P. vivax 41 (Pv41) protein has a signal peptide, one glutamate-rich domain in its central region, and two sexual stage s48/45 domains, and is characterized as a gametocyte surface protein; however, this protein may be expressed principally on the merozoite surface of parasites. The previous study reported the transcription, blood-stage expression, and subcellular localization of Pv41 within the parasite. In this study, the recombinant Pv41 protein was expressed as a soluble form, of a molecular mass ∼44kDa, by a cell-free expression system and was specifically recognized by animal immune sera and vivax patient sera. Evaluation of the human humoral immune response to Pv41 indicated a high immunogenicity, with 62.5% sensitivity and 95% specificity, by protein array. Immunofluorescence assays (IFA) using polyclonal anti-Pv41 antibodies showed that Pv41 was localized on the merozoite surface. The high immunogenicity of Pv41 indicates its potential as a vivax malaria vaccine candidate antigen, particularly in light of its location on the merozoite surface of the parasite.
    Acta tropica 03/2013; DOI:10.1016/j.actatropica.2013.03.002 · 2.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A novel Babesia bovis gene family encoding proteins with similarities to the Plasmodium 6cys protein family was identified by TBLASTN searches of the B. bovis genome using the sequence of the P. falciparum PFS230 protein as query, and was termed Bbo-6cys gene family. The Bbo-cys6 gene family contains six genes termed Bbo-6cys-A, B, C, D, E and F encoding for proteins containing an arrangement of 6 cysteine residues. The Bbo-6cys genes A, B, C, D, and E are tandemly arranged as a cluster of Chromosome 2 in the B. bovis genome, whereas gene F is located in a distal region in the same chromosome. The Bbo-6cys-E gene, with higher homology to PFS230, was selected for further examination. Immunoblot analysis using recombinant Bbo-6cys-E protein and B. bovis-positive bovine serum demonstrated expression by the parasite and immunogenicity during B. bovis infection. Immunofluorescence analysis using anti-Bbo-6cys-E antibodies confirmed expression of Bbo-6cys-E in in vitro blood stages of B. bovis. In addition, polyclonal antisera against both recombinant Bbo-6cys-E and specific synthetic peptides containing predicted B-cell epitopes of Bbo-6cys-E, significantly inhibited erythrocyte invasion by B. bovis in in vitro neutralization assays, suggesting an important functional role for this protein. Identification of this new gene family in B. bovis and further investigation on its biological significance may aid our understanding of the bovine, tick and parasite relationships and the development of improved control methods against B. bovis infection in cattle.
    Parasitology International 09/2010; 60(1):13-8. DOI:10.1016/j.parint.2010.09.004 · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Malaria transmission requires that the parasites differentiate into gametocytes prior to ingestion by a mosquito during a blood meal. Once in the mosquito midgut the gametocytes emerge from red blood cells (RBCs), fertilize, develop into ookinetes and finally infectious sporozoites. Gamete surface antigen, Pfs230, is an important malaria transmission-blocking vaccine candidate, but its function has remained unclear. Two clones with distinct Pfs230 gene disruptions (Delta1.356 and Delta2.560) and a clone with a disruption of Pfs48/45 were used to evaluate the role of Pfs230 in the mosquito midgut. Pfs230 disruptants successfully emerge from RBCs and male gametes exflagellate producing microgametes. However, exflagellating Pfs230-minus males, in the presence or absence of Pfs48/45, are unable to interact with RBCs and form exflagellation centres. Oocyst production and mosquito infectivity is also significantly reduced, 96-92% and 76-71% respectively. In contrast, in the Pfs230 disruptants the expression and localization of other known sexual stage-specific antigens, including Pfs48/45, Pfs47, the Pfs230 paralogue (PfsMR5), Pfs16 or Pfs25, were not altered and the Pfs230-minus gametes retained resistance to the alternative pathway of human complement. These results suggest that Pfs230 is the surface molecule on males that mediates RBC binding and plays an important role in oocyst development, a critical step in malaria transmission.
    Molecular Microbiology 09/2006; 61(4):991-8. DOI:10.1111/j.1365-2958.2006.05284.x · 5.03 Impact Factor