The biosynthesis and post-translational modification of Pbs21 an ookinete-surface protein of Plasmodium berghei

Blanco, A. Richard Alejo; Páez, Araceli; Gerold, Peter; Dearsly, A. L.; Margos, Gabriele; Schwarz, Ralph Τ.; Barker, Guy C.; Rodríguez, M. C.; Sinden, Robert E.

doi:10.1016/s0166-6851(98)00162-5

Cited by 30 publications

(11 citation statements)

References 24 publications

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“…Furthermore, following phase separation, Pbs21 expressed by transgenic parasites was found exclusively in the detergent phase, as is Pbs21 expressed by ookinetes (1). The hydrophobic properties of Pbs21 expressed by ookinete stages was attributed to the presence of a GPI anchor (1). The data presented here are consistent with a membrane anchor modification of Pbs21 expressed by transformed parasites; its precise nature, however, needs further investigation.…”

Section: Discussionsupporting

confidence: 70%

“…Transgenically expressed Pbs21 was indistinguishable to ookinete-derived Pbs21 in terms of molecular weight and conformation. Furthermore, following phase separation, Pbs21 expressed by transgenic parasites was found exclusively in the detergent phase, as is Pbs21 expressed by ookinetes (1). The hydrophobic properties of Pbs21 expressed by ookinete stages was attributed to the presence of a GPI anchor (1).…”

Section: Discussionmentioning

confidence: 98%

“…Transcription of the gene is confined to female gametocytes and begins 16 to 19 h into their development in the blood of the vertebrate host, resulting in the localized accumulation of mRNA in mature female gametocytes (18,22,26,31). In contrast, translation of the Pbs21 mRNA normally occurs only after gametocyte activation in the mosquito midgut in macrogametes, zygotes, ookinetes, and young oocysts (23,24) and is triggered at the same time as gametogenesis (1).…”

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confidence: 99%

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Transgenic Expression of a Mosquito-Stage Malarial Protein, Pbs21, in Blood Stages of Transformed Plasmodium berghei and Induction of an Immune Response upon Infection

et al. 1998

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Pbs21 is a surface protein of the ookinete of Plasmodium berghei, which can induce a potent transmission-blocking immune response. Pbs21 is normally expressed only by parasite stages in the mosquito, i.e., female gametes/zygotes, ookinetes, and oocysts. However, the Pbs21 gene is transcribed in female gametocytes which circulate in the bloodstream of the host, where translation of the resulting mRNA is totally repressed. Episomal transfection has been used to investigate whether expression of Pbs21 protein could be achieved in blood stages of the parasite. By using plasmid pMD221, the complete mRNA-encoding region of Pbs21, flanked only by 218 nucleotides (nt) of its promoter region and 438 nt of its 3′ region downstream from the polyadenylation site, was introduced into the blood stages of gametocyte-producing and non-gametocyte-producing clones of P. berghei. In both of these transformed parasite lines, Pbs21 protein was expressed in asexual trophozoites, schizonts, and, when present, in both male and female gametocytes. Hence, the flanking regions present are sufficient to allow transcription but lack the elements that exert natural control of sex- and stage-specific transcription. The mRNA and the protein expressed by transformed blood stages were indistinguishable from the wild-type forms by the criteria tested, and the protein was recognized by both conformation-dependent and conformation-independent monoclonal antibodies raised against native Pbs21. In mice infected with transformed non-gametocyte-producing parasites, a Pbs21-specific immune response was induced and characterized with respect to isotype (IgG2a/IgG2b) and quantity (11.5 ± 10 μg/ml) of antibody produced. However, as found in previous studies, these antibody levels were insufficient to inhibit development of the parasites in the mosquito. The ability to express mosquito midgut-stage antigens in blood-stage parasites will facilitate further investigations of molecular and immunological properties of these proteins.

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Section: Discussionsupporting

confidence: 70%

Section: Discussionmentioning

confidence: 98%

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confidence: 99%

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Transgenic Expression of a Mosquito-Stage Malarial Protein, Pbs21, in Blood Stages of Transformed Plasmodium berghei and Induction of an Immune Response upon Infection

et al. 1998

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“…1992 ). The expression of the full length, and truncated recombinant proteins [Pbs21(1–213) and Pbs21(1–188), respectively] was studied by SDS‐PAGE, Western blots and indirect fluorescent antibody tests as described previously ( Alejo‐Blanco et al . 1 999)…”

Section: Methodsmentioning

confidence: 99%

The roles of the glycosylphosphatidylinositol anchor on the production and immunogenicity of recombinant ookinete surface antigen Pbs21 of Plasmodium berghei when prepared in a baculovirus expression system

Martínez

Margos

Barker

et al. 2000

Parasite Immunology

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Malarial ookinetes express an immunodominant surface protein (P28) that is a priority candidate for the development of transmission-blocking vaccines. The full length P28 gene from Plasmodium berghei [Pbs21(1-213)] and a deletion construct [Pbs21(1-188)] encoding a protein that lacks the 25 C-terminal amino acids, including the glycosylphosphatidylinositol (GPI) anchor signal, were expressed in insect cells using baculovirus vectors. Pbs21(1-213) protein is strongly hydrophobic, found in the cytoplasm and on the surface of Spodoptera Sf21 cells, and in the culture medium. Pbs21(1-188) protein was largely found in the aqueous phase of the medium and in the cytoplasm of Sf21 cells, but was not detected on the cell surface. The presence of 25 C-terminal amino acids is therefore critical to the attachment of recombinant Pbs21 to the parasite plasma membrane. Mice were immunized subcutaneously or intramuscularly with affinity purified recombinant Pbs21(1-213), Pbs21(1-188) or native Pbs21 proteins. Following two immunizations, native Pbs21 induces higher titres when administered by either route, than the recombinant protein bearing an insect GPI anchor, which in turn is markedly more immunogenic than the recombinant polypeptide lacking a GPI anchor. When specific anti Pbs21 antibody titres exceeded 1 mg/ml all three antigens were capable of inducing transmission blockade > or = 90%, below 1 mg/ml blockade did not correlate with antibody concentration.

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“…Among these proteins, some restricted to the P. falciparum sexual stages (Pfs230, Pfs48/45 Pfs28/Pfs25) and others to that of P. vivax (Pv28/25, Pvs230 and Pvs48/45) are expressed on the surface of the sexual parasite stage where they can accomplish critical functions for parasite development (Table II) (Moreira et al 2004, Coutinho-Abreu & Ramalho-Ortigao 2010). Some of these antigens belong to a protein superfamily characterized by conserved structures with six cystein-rich glycoprotein domains that contain an N-terminal secretory signal sequence domain followed by four similar epidermal growth factor-like domains anchored by a GPI moiety (Kaslow et al 1988, Alejo-Blanco et al 1999). These are conserved across Plasmodia species and highly conserved geographically (Kocken et al 1993).…”

Section: Strategies and Protein Candidates For Tbv Developmentmentioning

confidence: 99%

Malaria transmission blocking immunity and sexual stage vaccines for interrupting malaria transmission in Latin America

Arévalo‐Herrera

Solarte

Marín

et al. 2011

Mem. Inst. Oswaldo Cruz

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Malaria is a vector-borne disease that is considered to be one of the most serious public health problems due to its high global mortality and morbidity rates. Although multiple strategies for controlling malaria have been used, many have had limited impact due to the appearance and rapid dissemination of mosquito resistance to insecticides, parasite resistance to multiple antimalarial drug, and the lack of sustainability. Individuals in endemic areas that have been permanently exposed to the parasite develop specific immune responses capable of diminishing parasite burden and the clinical manifestations of the disease, including blocking of parasite transmission to the mosquito vector. This is referred to as transmission blocking (TB) immunity (TBI) and is mediated by specific antibodies and other factors ingested during the blood meal that inhibit parasite development in the mosquito. These antibodies recognize proteins expressed on either gametocytes or parasite stages that develop in the mosquito midgut and are considered to be potential malaria vaccine candidates. Although these candidates, collectively called TB vaccines (TBV), would not directly stop malaria from infecting individuals, but would stop transmission from infected person to non-infected person. Here, we review the progress that has been achieved in TBI studies and the development of TBV and we highlight their potential usefulness in areas of low endemicity such as Latin America.

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The biosynthesis and post-translational modification of Pbs21 an ookinete-surface protein of Plasmodium berghei

Cited by 30 publications

References 24 publications

Transgenic Expression of a Mosquito-Stage Malarial Protein, Pbs21, in Blood Stages of Transformed Plasmodium berghei and Induction of an Immune Response upon Infection

Transgenic Expression of a Mosquito-Stage Malarial Protein, Pbs21, in Blood Stages of Transformed Plasmodium berghei and Induction of an Immune Response upon Infection

The roles of the glycosylphosphatidylinositol anchor on the production and immunogenicity of recombinant ookinete surface antigen Pbs21 of Plasmodium berghei when prepared in a baculovirus expression system

Malaria transmission blocking immunity and sexual stage vaccines for interrupting malaria transmission in Latin America

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