Overlooked post-translational modifications of proteins in Plasmodium falciparum: N- and O-glycosylation - A Review

Macedo, Cristiana Santos de; Schwarz, Ralph Τ.; Todeschini, Adriane R.; Previato, José O.

doi:10.1590/s0074-02762010000800001

Cited by 35 publications

(23 citation statements)

References 77 publications

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“…Additional efforts to optimize immunogenicity has focused on codon optimization of the coding sequence to improve expression in mammalian cells after immunization [33], and assessing the impact of protein glycosylation [34]. The latter has the potential to be critical especially since Plasmodium proteins do not undergo modification by N-linked glycosylation [35–37], and proteins encoded by DNA plasmids are expected to undergo glycosylation when expressed in mammalian cells. A few studies have examined the impact of N-linked glycosylation on the immunogenicity of P. falciparum asexual stage antigens MSP-1 and AMA-1 [38–40].…”

Section: Introductionmentioning

confidence: 99%

Immunogenicity and malaria transmission reducing potency of Pfs48/45 and Pfs25 encoded by DNA vaccines administered by intramuscular electroporation

Datta

Bansal

Gerloff

et al. 2017

Vaccine

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Pfs48/45 and Pfs25 are leading candidates for the development of Plasmodium falciparum transmission blocking vaccines (TBV). Expression of Pfs48/45 in the erythrocytic sexual stages and presentation to the immune system during infection in the human host also makes it ideal for natural boosting. However, it has been challenging to produce a fully folded, functionally active Pfs48/45, using various protein expression platforms. In this study, we demonstrate that full-length Pfs48/45 encoded by DNA plasmids is able to induce significant transmission reducing immune responses. DNA plasmids encoding Pfs48/45 based on native (WT), codon optimized (SYN), or codon optimized and mutated (MUT1 and MUT2), to prevent any asparagine (N)-linked glycosylation were compared with or without intramuscular electroporation (EP). EP significantly enhanced antibody titers and transmission blocking activity elicited by immunization with SYN Pfs48/45 DNA vaccine. Mosquito membrane feeding assays also revealed improved functional immunogenicity of SYN Pfs48/45 (N-glycosylation sites intact) as compared to MUT1 or MUT2 Pfs48/45 DNA plasmids (all N-glycosylation sites mutated). Boosting with recombinant Pfs48/45 protein after immunization with each of the different DNA vaccines resulted in significant boosting of antibody response and improved transmission reducing capabilities of all four DNA vaccines. Finally, immunization with a combination of DNA plasmids (SYN Pfs48/45 and SYN Pfs25) also provides support for the possibility of combining antigens targeting different life cycle stages in the parasite during transmission through mosquitoes.

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Section: Introductionmentioning

confidence: 99%

Immunogenicity and malaria transmission reducing potency of Pfs48/45 and Pfs25 encoded by DNA vaccines administered by intramuscular electroporation

Datta

Bansal

Gerloff

et al. 2017

Vaccine

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“…Posttranslational modifications such as N-glycosylation have been known to play a crucial role in the folding, stability, and functional integrity of proteins (18,19). Glycosylation of proteins in Plasmodium has remained highly controversial (20), and a recent study has suggested formation of severely truncated N-glycan side chains due to the absence of glycosyltransferases required for precursor side chain generation (21). The impact of N-linked glycosylation has been studied with respect to viral virulence and immune evasion (reviewed in reference 22) as well as in limited vaccine studies with DNA plasmids encoding viral antigens (23).…”

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confidence: 99%

Evaluation of the Impact of Codon Optimization and N-Linked Glycosylation on Functional Immunogenicity of Pfs25 DNA Vaccines Delivered by In Vivo Electroporation in Preclinical Studies in Mice

Datta

Bansal

Kumar

et al. 2015

Clin Vaccine Immunol

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bPlasmodium falciparum sexual stage surface antigen Pfs25 is a well-established candidate for malaria transmission-blocking vaccine development. Immunization with DNA vaccines encoding Pfs25 has been shown to elicit potent antibody responses in mice and nonhuman primates. Studies aimed at further optimization have revealed improved immunogenicity through the application of in vivo electroporation and by using a heterologous prime-boost approach. The goal of the studies reported here was to systematically evaluate the impact of codon optimization, in vivo electroporation, and N-linked glycosylation on the immunogenicity of Pfs25 encoded by DNA vaccines. The results from this study demonstrate that while codon optimization and in vivo electroporation greatly improved functional immunogenicity of Pfs25 DNA vaccines, the presence or absence of N-linked glycosylation did not significantly impact vaccine efficacy. These findings suggest that N-glycosylation of Pfs25 encoded by DNA vaccines is not detrimental to overall transmission-blocking efficacy. Malaria caused by Plasmodium species is still endemic in 97 countries, and WHO estimated that 3.3 billion people are at risk of disease, with ϳ584,000 deaths reported in 2013 (1). Plasmodium falciparum is responsible for the most morbidity and mortality and is thus the major focus of current vaccine development efforts (2). The malaria eradication research agenda (malERA) initiative of 2011 underscored the need for a multipronged approach for malaria control and elimination that includes vaccines targeting infection (3) and transmission along with various control measures currently in use such as indoor residual spraying and insecticide-treated mosquito nets (4).Malaria transmission-blocking vaccines (TBVs) target the sexual life cycle stages of the parasite that develop in the mosquito vector with the goal of interrupting transmission and further spread of the infection (5). The primary mode of action of TBVs is via induction of antibodies that target surface antigens expressed in the sexual stages of the parasite. P. falciparum TBV candidates include prefertilization antigens Pfs230 and Pfs48/45 and postfertilization antigens Pfs25 and Pfs28 (6, 7). So far, vaccine approaches based on recombinant protein-adjuvant formulations have met with limited success due to the complex conformational nature of these antigens, often resulting in improperly folded, unstable, and aggregated proteins (6). DNA vaccines encoding specific P. falciparum TBV target antigens offer alternatives to traditional platforms as seen in murine (8) and nonhuman primate (9) models. Additional benefits for use of DNA vaccines include ease of design and sequence modification, stability, and transportability (10). Studies in mice with Pfs25 DNA plasmids showed high TBV activity with Ͼ95% oocyst reduction in the mosquitoes (8). Similar studies in rhesus macaques, however, revealed only modest immunogenicity even after four immunization doses and required heterologous boosting with recombinant protein for ...

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“…This is probably because the exact nature of protein glycosylation in Plasmodium spp. has been contentious [2,3] and because glycopeptides were for a long time incorrectly thought to be T-independent antigens [4].Uncertainty surrounding protein glycosylation in Plasmodium parasites was driven in the past by an inability of common glycan-recognizing lectins to bind to parasite proteins and poor histological staining of parasites by periodic acid-Schiff methods. Indeed, it appeared that the installation of glycosylphosphatidylinositol anchors was the only type of glycosylation that Plasmodium parasites undertook [5].…”

mentioning

confidence: 99%

“…Genome sequencing of Plasmodium spp. also revealed the absence of genes required to build and remodel common eukaryotic glycans [2,3]. Even so, homologs of several genes required for protein glycosylation are present and conserved in the genomes of Plasmodium spp.…”

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Implications of Plasmodium Glycosylation on Vaccine Efficacy and Design

Goddard‐Borger

Boddey

2018

Future Microbiol.

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Malaria remains a dire public health problem, despite significant efforts to control and eliminate the disease, and is caused by infection with any one of six species of Plasmodium parasite. Although focused control measures have halved the number of annual deaths from malaria to approximately 630,000 [1], the disease is still endemic in 91 countries and resistance to antimalarials continues to spread. Malaria eradication will require a combination of control measures including a vaccine that affords effective protection against different species and strains of Plasmodium parasites; a need that is currently unmet. Although much has been written about the design and evaluation of malaria vaccines, relatively little has been said about the impact that glycosylation has on the efficacy of existing or emerging vaccine technologies. This is probably because the exact nature of protein glycosylation in Plasmodium spp. has been contentious [2,3] and because glycopeptides were for a long time incorrectly thought to be T-independent antigens [4].Uncertainty surrounding protein glycosylation in Plasmodium parasites was driven in the past by an inability of common glycan-recognizing lectins to bind to parasite proteins and poor histological staining of parasites by periodic acid-Schiff methods. Indeed, it appeared that the installation of glycosylphosphatidylinositol anchors was the only type of glycosylation that Plasmodium parasites undertook [5]. Genome sequencing of Plasmodium spp. also revealed the absence of genes required to build and remodel common eukaryotic glycans [2,3]. Even so, homologs of several genes required for protein glycosylation are present and conserved in the genomes of Plasmodium spp. and metabolomic analyses of parasite material has demonstrated the presence of the nucleotide sugars required for protein glycosylation, which alluded to the existence of as yet undiscovered parasite glycans.With the aid of modern protein mass spectrometry methods, several research groups have recently tackled the issues of glycan lability and relatively small sample sizes to begin characterizing the true diversity of Plasmodium protein glycosylation [6][7][8][9][10][11][12]. Evidence for the synthesis of short N-linked glycans has been reported in asexual blood stages of Plasmodium falciparum [6], and there is every reason to expect that these modifications will be found in other life cycle stages as well. Cell surface proteomic studies of P. falciparum and P. vivax sporozoites, the two species responsible for the majority of malaria cases and deaths, have demonstrated that O-and C-linked glycans exist on the essential adhesive proteins, TRAP and CSP [8,10]. These abundant surface proteins are required for parasite infectivity and are prime vaccine candidates because sporozoites represent a population bottleneck in the life cycle as parasites pass from mosquito to human and establish an infection in the liver. Moreover, strain-transcending sterile immunity can be achieved through strong B-and T-cell-dependent respons...

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Overlooked post-translational modifications of proteins in Plasmodium falciparum: N- and O-glycosylation - A Review

Cited by 35 publications

References 77 publications

Immunogenicity and malaria transmission reducing potency of Pfs48/45 and Pfs25 encoded by DNA vaccines administered by intramuscular electroporation

Immunogenicity and malaria transmission reducing potency of Pfs48/45 and Pfs25 encoded by DNA vaccines administered by intramuscular electroporation

Evaluation of the Impact of Codon Optimization and N-Linked Glycosylation on Functional Immunogenicity of Pfs25 DNA Vaccines Delivered by In Vivo Electroporation in Preclinical Studies in Mice

Implications of Plasmodium Glycosylation on Vaccine Efficacy and Design

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