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plasmodium falciparum

Serologic responses to the PfEMP1 DBL-CIDR head structure may be a better indicator of malaria exposure than those to the DBL-α tag

August 13, 2019 - 15:52 -- Open Access
Author(s): 
Emily M. Stucke, Amadou Niangaly, Mark A. Travassos, et al.
Reference: 
Malaria Journal 2019 18:273, 13 August 2019

Plasmodium falciparum erythrocyte membrane protein-1 (PfEMP1) antigens play a critical role in host immune evasion. Serologic responses to these antigens have been associated with protection from clinical malaria, suggesting that antibodies to PfEMP1 antigens may contribute to natural immunity. The first N-terminal constitutive domain in a PfEMP1 is the Duffy binding-like alpha (DBL-α) domain, which contains a 300 to 400 base pair region unique to each particular protein (the DBL-α “tag”). This DBL-α tag has been used as a marker of PfEMP1 diversity and serologic responses in malaria-exposed populations. In this study, using sera from a malaria-endemic region, responses to DBL-α tags were compared to responses to the corresponding entire DBL-α domain (or “parent” domain) coupled with the succeeding cysteine-rich interdomain region (CIDR).

Diverse origin of Plasmodium falciparum in northwest Ecuador

August 5, 2019 - 17:01 -- Open Access
Author(s): 
Claudia A. Vera-Arias, L. Enrique Castro, Javier Gómez-Obando and Fabián E. Sáenz
Reference: 
Malaria Journal 2019 18:251, 26 July 2019

Ecuador plans to eliminate malaria by 2020, and the country has already seen a decrease in the number of cases from more than 100,000 in 2000 to only 618 in 2015. Around 30% of malaria infections in Ecuador are caused by Plasmodium falciparum. Most malaria population genetics studies performed in Latin America, especially in the Pacific Coast, indicate a high clonality and a clear structure of P. falciparum populations. It was shown that an outbreak of P. falciparum in northwest Ecuador was the result of a clonal expansion of parasites circulating at low levels in the country or re-invading Ecuador from neighbouring territories. However, general characteristics of P. falciparum circulating in the northwest coast of Ecuador have not been determined. The main goal of this study was to genetically characterize the population structure of P. falciparum in coastal Ecuadorian localities bordering with Colombia.

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Infected RBC flag/parameter provided by Mindray BC-6800 haematology analyzer aid the diagnosis of malaria

August 5, 2019 - 16:37 -- Open Access
Author(s): 
Yi Sun, Daijun Xiang, Chen Chen, Shang He, Huan Qi and Chengbin Wang
Reference: 
Malaria Journal 2019 18:262, 31 July 2019

The Mindray BC-6800 haematology analyzer (BC-6800) provides a dedicated flag ‘Infected RBC’ (InR) and the number of InR (InR#)/the permillage of InR (InR‰) in routine blood testing as a screening tool for malaria in endemic areas. This study sought to evaluate the effectiveness of the BC-6800 flag parameter for aiding the diagnosis of malaria.

Delayed death in the malaria parasite Plasmodium falciparum is caused by disruption of prenylation-dependent intracellular trafficking

July 30, 2019 - 10:18 -- Open Access
Author(s): 
Kit Kennedy, Simon A. Cobbold, Stuart A. Ralph, et al.
Reference: 
PLoS Biol 17(7): e3000376

Apicomplexan parasites possess a plastid organelle called the apicoplast. Inhibitors that selectively target apicoplast housekeeping functions, including DNA replication and protein translation, are lethal for the parasite, and several (doxycycline, clindamycin, and azithromycin) are in clinical use as antimalarials.

Changing pattern of the genetic diversities of Plasmodium falciparum merozoite surface protein-1 and merozoite surface protein-2 in Myanmar isolates

July 21, 2019 - 21:42 -- Open Access
Author(s): 
Hương Giang Lê, Jung-Mi Kang, Byoung-Kuk Na, et al.
Reference: 
Malaria Journal 2019 18:241, 16 July 2019

Plasmodium falciparum merozoite surface protein-1 (PfMSP-1) and -2 (PfMSP-2) are major blood-stage vaccine candidate antigens. Understanding the genetic diversity of the genes, pfmsp-1 and pfmsp-2, is important for recognizing the genetic structure of P. falciparum, and the development of an effective vaccine based on the antigens. In this study, the genetic diversities of pfmsp-1 and pfmsp-2 in the Myanmar P. falciparum were analysed.

Temporal changes in Plasmodium falciparum reticulocyte binding protein homolog 2b (PfRh2b) in Senegal and The Gambia

July 21, 2019 - 21:35 -- Open Access
Author(s): 
Cyrille K. Diédhiou, Rahama A. Moussa, Ambroise D. Ahouidi, et al.
Reference: 
Malaria Journal 2019 18:239, 16 July 2019

The Plasmodium falciparum reticulocyte binding protein homolog 2b (PfRh2b) is an important P. falciparum merozoite ligand that mediates invasion of erythrocytes by interacting with a chymotrypsin-sensitive “receptor Z”. A large deletion polymorphism is found in the c-terminal ectodomain of this protein in many countries around the world, resulting in a truncated, but expressed protein. The varying frequencies by region suggest that there could be region specific immune selection at this locus. Therefore, this study was designed to determine temporal changes in the PfRh2b deletion polymorphism in infected individuals from Thiès (Senegal) and Western Gambia (The Gambia). It was also sought to determine the selective pressures acting at this locus and whether prevalence of the deletion in isolates genotyped by a 24-SNP molecular barcode is linked to background genotype or whether there might be independent selection acting at this locus.

Controlled human malaria infection with Plasmodium falciparum demonstrates impact of naturally acquired immunity on virulence gene expression

July 16, 2019 - 17:00 -- Open Access
Author(s): 
Anna Bachmann, Ellen Bruske, Egbert Tannich, et al.
Reference: 
PLoS Pathog 15(7): e1007906

The pathogenesis of Plasmodium falciparum malaria is linked to the variant surface antigen PfEMP1, which mediates tethering of infected erythrocytes to the host endothelium and is encoded by approximately 60 var genes per parasite genome.

Antigenic cartography of immune responses to Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1)

July 16, 2019 - 16:22 -- Open Access
Author(s): 
James Tuju, Margaret J. Mackinnon, Britta C. Urban, et al.
Reference: 
PLoS Pathog 15(7): e1007870

Naturally acquired clinical immunity to Plasmodium falciparum is partly mediated by antibodies directed at parasite-derived antigens expressed on the surface of red blood cells which mediate disease and are extremely diverse.

Competition for hosts modulates vast antigenic diversity to generate persistent strain structure in Plasmodium falciparum

July 16, 2019 - 16:21 -- Open Access
Author(s): 
Shai Pilosof, Qixin He, Kathryn E. Tiedje, Shazia Ruybal-Pesántez, Karen P. Day, Mercedes Pascual
Reference: 
PLoS Biol 17(6): e3000336

In their competition for hosts, parasites with antigens that are novel to the host immune system will be at a competitive advantage.

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