The 11-1 gene of Plasmodium falciparum codes for distinct fast evolving repeats.

Scherf, Artur; Hilbich, Caroline; Sieg, Karl; Mattei, Denise; Mercereau‐Puijalon, Odile; Müller‐Hill, Benno

doi:10.1002/j.1460-2075.1988.tb02922.x

Cited by 63 publications

(25 citation statements)

References 39 publications

(29 reference statements)

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“…The PflJ -J gene of P.falciparum is a large locus (> 30 kb) with a nucleotide sequence that predicts a glutamic acid-rich polypeptide containing three blocks of tandem repeats of three, six and nine amino acids (Kahane et al, 1987;Scherf et al, 1988). The structure, function and cellular location of the Pfl 1-1 protein have been difficult to determine because of immunological cross-reactivity between putative Pfl -1 proteins and other malarial proteins.…”

Section: Resultsmentioning

confidence: 99%

Gene inactivation of Pf11-1 of Plasmodium falciparum by chromosome breakage and healing: identification of a gametocyte-specific protein with a potential role in gametogenesis.

et al. 1992

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We report the identification of the product of the Plasmodium falciparum Pf11‐1 gene and demonstrate that it is a gametocyte‐specific protein that has a potential role in the rupture of the host erythrocyte and emergence of the gametes (gametogenesis). The Pf11‐1 gene is a large locus (30 kb) whose sequence predicts a glutamic acid‐rich polypeptide. Our identification of the Pf11‐1 gene product as gametocyte specific was greatly facilitated by the isolation of a mutant parasite clone in which greater than 90% of the Pf11‐1 gene was deleted. Molecular analysis of the mutant locus suggests that the underlying genetic mechanism is chromosome breakage and subsequent healing by the addition of telomere repeats. PCR‐based analysis showed that similar DNA rearrangements occur commonly in small subpopulations of most laboratory strains, suggesting that the Pf11‐1 locus represents a fragile chromosome region. Northern blot analysis demonstrates that a large Pf11‐1 gene‐specific transcript (much greater than 10 kb) is present in gametocytes but not in asexual blood stage parasites. The Pf11‐1 protein was localized by electron microscopy to granules in the cytoplasm of gametocytes adjacent to the membrane of the parasitophorous vacuole. Following in vitro stimulation of gametogenesis, the Pf11‐1 protein was found in the membrane of lysed erythrocytes, suggesting a role for Pf11‐1 in erythrocyte rupture within the mosquito gut.

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Section: Resultsmentioning

confidence: 99%

Gene inactivation of Pf11-1 of Plasmodium falciparum by chromosome breakage and healing: identification of a gametocyte-specific protein with a potential role in gametogenesis.

et al. 1992

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“…The repeat consensus sequence is (P-E-E-X-X-E-E-X-X), where X is generally a hydrophobic amino acid such as valine, leucine or isoleucine [12].…”

Section: Detection Of Pfll-1 Peptide-specific T Cells In Humansmentioning

confidence: 99%

Immune response in mouse and malaria‐exposed humans to peptides derived from Pfl1‐1, a highly repetitive megadalton protein of Plasmodium falciparum

et al. 1993

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We have investigated the immune response against the Plasmodium falciparum gametocyte-specific antigen Pf11-1. This megadalton parasite molecule has been implicated in the process of erythrocyte rupture during gametogenesis. The molecule is composed in great part of degenerated nonapeptide motifs which are tandemly repeated several hundred times. A computer algorithm searching for T sites predicted that the entire repeat region of the Pf11-1 represents potential T cell antigenic major histocompatibility complex class II-binding sites. To test this hypothesis, synthetic peptides corresponding to two nonamer subtype repeats, differing only at two amino acid positions, were used to immunize congenic mouse strains. Both peptides were shown to contain both B and T cell epitopes. The immune response is restricted to the H-2d and H-2k haplotypes. The T cell response against the peptides appeared to be highly specific, clearly discriminating between the two similar nonamer repeat sequences, whereas the humoral response produced cross-reacting antibodies. We also investigated the humoral and T cell reactivities of P. falciparum-primed individuals in West Africa against the synthetic Pf11-1 peptides. Among 51 individuals 35 had antibodies to at least one of the two peptides and a majority of them (28) had antibodies reacting with both peptides. The cellular response was analyzed by [3H]thymidine incorporation or interferon-gamma release. There was considerable variation in the response to the two peptides. Among the human samples 36% responded to one repeat subtype, while only 13% responded to the second subtype. Interestingly, in individual donors the T cell response to both peptides are associated, suggesting that, as shown for mice, the response is restricted by a genetic element. The data obtained on the two subtypes of the nonamer repeat region suggest that the entire Pf11-1 molecule might induce an unusually heterogenous B and T cell response during natural infection in man.

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“…It is possible that the full-length versions of Pf7 and Pfl2 may contain additional noncoding or perhaps even coding exons, although most malaria genes characterized to date appear to be contained within a single exon (19). In any case, it is very likely that this method of genomic expression cloning can also be used to clone parasite genes whose coding segments are interrupted by introns, since the signals used for RNA splicing in malaria are apparently identical with those used in higher eukaryotes (19,29).…”

Section: Methodsmentioning

confidence: 99%

Genes for Plasmodium falciparum surface antigens cloned by expression in COS cells.

Elliott¹,

Albrecht²,

Gilladoga³

et al. 1990

Proc. Natl. Acad. Sci. U.S.A.

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Two genes encoding membrane antigens of Plasmodiumfalciparum were isolated by transient expression in mammalian cells and selection with human immune sera from African adults exposed to P. falciparum malaria. COS-7 cells were transfected with a plasmid expression library constructed from P. falciparum genomic DNA, and cells expressing reactive malaria antigens on their surface were enriched by adherence to antibody-coated dishes. One of the genes isolated is distinctive in that it does not contain repeat sequences typical of many malarial genes cloned by immunoscreening of bacterial expression libraries. The second gene apparently encodes a polymorphic version of the P. falciparum merozoite surface antigen Ag513, since the two sequences are identical in the 5' and 3' coding regions but diverge completely in the center. The COS-7 expression system provides an alternate means for cloning genes encoding malarial membrane antigens by using those antibodies in complex immune sera that bind membraneassociated, nondenatured molecules.Proteins expressed on the surface of parasites constitute potential target antigens for vaccine development. These molecules are accessible to the immune system and also may mediate functions vital for parasite survival such as cell attachment, host-cell invasion, or membrane transport. In the case of Plasmodium falciparum, surface membrane antigens of the asexual blood stages are of special interest because these stages are responsible for the high morbidity and mortality of P. falciparum malaria. The P. falciparum genes characterized to date have been cloned largely in bacterial expression systems, typically by using Agtll cDNA or genomic libraries in Escherichia coli and screening with human immune serum (1, 2). However, with these methods few genes for malarial surface antigens have been cloned, possibly due to poor expression of membrane proteins in E. coli and the fact that bacterial fusion proteins lack epitopes dependent on native secondary or higher order protein conformations. In this paper we show that genes encoding parasite membrane proteins can be isolated directly by expression in mammalian cells and selection for cells bearing heterologous surface antigens by using human immune serum from individuals exposed to the infection of interest. This method should be generally applicable to a number of parasitic diseases. Although the genes for a number of different human cell surface antigens have been cloned by transient expression in mammalian cells, these have been isolated exclusively from cDNA libraries, and immunological selection has depended on specific monoclonal antibodies (3-6). We demonstrate that genomic libraries can also be used in similar expression cloning and that polyspecific antibodies from human serum can be used for selection of transfected cells. MATERIALS AND METHODScDNA Expression Vector pJFE14. This simian virus 40 (SV40)-based COS cell expression vector is derived from pSSD2. The vector pSSD2 is similar to the original Okayama and Berg vector pcD...

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The 11-1 gene of Plasmodium falciparum codes for distinct fast evolving repeats.

Cited by 63 publications

References 39 publications

Gene inactivation of Pf11-1 of Plasmodium falciparum by chromosome breakage and healing: identification of a gametocyte-specific protein with a potential role in gametogenesis.

Gene inactivation of Pf11-1 of Plasmodium falciparum by chromosome breakage and healing: identification of a gametocyte-specific protein with a potential role in gametogenesis.

Immune response in mouse and malaria‐exposed humans to peptides derived from Pfl1‐1, a highly repetitive megadalton protein of Plasmodium falciparum

Genes for Plasmodium falciparum surface antigens cloned by expression in COS cells.

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