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plasmodium falciparum

Safety, infectivity and immunogenicity of a genetically attenuated blood-stage malaria vaccine

November 25, 2021 - 13:03 -- Open Access
Author(s): 
Webster R, Sekuloski S, McCarthy JS, et al.
Reference: 
BMC Med. 2021 Nov 22;19(1):293

There is a clear need for novel approaches to malaria vaccine development. We aimed to develop a genetically attenuated blood-stage vaccine and test its safety, infectivity, and immunogenicity in healthy volunteers. Our approach was to target the gene encoding the knob-associated histidine-rich protein (KAHRP), which is responsible for the assembly of knob structures at the infected erythrocyte surface. Knobs are required for correct display of the polymorphic adhesion ligand P. falciparum erythrocyte membrane protein 1 (PfEMP1), a key virulence determinant encoded by a repertoire of var genes.

Genetic diversity of plasmodium falciparum isolates in Minna, North Central Nigeria inferred by PCR genotyping of Merozoite surface protein 1 and 2

November 25, 2021 - 12:59 -- Open Access
Author(s): 
Hadijah UY, Innocent OCJ, Abdulkadir A, Abolarinwa SO, Samuel ES, Chidiebere OA
Reference: 
Infect Genet Evol. 2021 Nov 17:105143

North Central Nigeria is one region in Nigeria with a significant incidence of malaria caused majorly by Plasmodium falciparum. This study utilizes the msp1 and msp2 genes of P. falciparum to examine its diversity and multiplicity of infection (MOI). Blood samples were collected from 247 children across selected healthcare facilities in Minna, from infants and children aged 6 months to 17 years.

G-quadruplex RNA motifs influence gene expression in the malaria parasite Plasmodium falciparum

November 25, 2021 - 12:48 -- Open Access
Author(s): 
Dumetz F, Chow EY, Harris LM, Liew SW, Jensen A, Umar MI, Chung B, Chan TF, Merrick CJ, Kwok CK
Reference: 
Nucleic Acids Res. 2021 Nov 18:gkab1095

G-quadruplexes are non-helical secondary structures that can fold in vivo in both DNA and RNA. In human cells, they can influence replication, transcription and telomere maintenance in DNA, or translation, transcript processing and stability of RNA. We have previously showed that G-quadruplexes are detectable in the DNA of the malaria parasite Plasmodium falciparum, despite a very highly A/T-biased genome with unusually few guanine-rich sequences. Here, we show that RNA G-quadruplexes can also form in P. falciparum RNA, using rG4-seq for transcriptome-wide structure-specific RNA probing.

Not Open Access | Safety and efficacy of a three-dose regimen of Plasmodium falciparum sporozoite vaccine in adults during an intense malaria transmission season in Mali: a randomised, controlled phase 1 trial

November 25, 2021 - 12:35 -- NOT Open Access
Author(s): 
Sissoko MS, Healy SA, Duffy PE, et al.
Reference: 
Lancet Infect Dis. 2021 Nov 18:S1473-3099(21)00332-7

WHO recently approved a partially effective vaccine that reduces clinical malaria in children, but increased vaccine activity is required to pursue malaria elimination. A phase 1 clinical trial was done in Mali, west Africa, to assess the safety, immunogenicity, and protective efficacy of a three-dose regimen of Plasmodium falciparum sporozoite (PfSPZ) Vaccine (a metabolically active, non-replicating, whole malaria sporozoite vaccine) against homologous controlled human malaria infection (CHMI) and natural P falciparum infection.

NOT Open Access | Assessment of experimental malaria vaccine induced protection in pre-exposed populations

November 24, 2021 - 20:02 -- NOT Open Access
Author(s): 
Daubenberger C
Reference: 
Lancet Infect Dis. 2021 Nov 18:S1473-3099(21)00359-5

Efforts to control and further reduce morbidity and mortality caused by Plasmodium falciparum infections in all age groups will be substantially strengthened by development of efficacious malaria vaccines in malaria pre-exposed populations.

Red blood cell blood group A antigen level affects the ability of heparin and PfEMP1 antibodies to disrupt Plasmodium falciparum rosettes

November 23, 2021 - 09:29 -- Open Access
Author(s): 
Pontus Hedberg, Madle Sirel, Kirsten Moll, Mpungu Steven Kiwuwa, Petter Höglund, Ulf Ribacke and Mats Wahlgren
Reference: 
Malaria Journal 2021 20:441, 18 November 2021

The histo-blood group ABO system has been associated with adverse outcomes in COVID-19, thromboembolic diseases and Plasmodium falciparum malaria. An integral part of the severe malaria pathogenesis is rosetting, the adherence of parasite infected red blood cells (RBCs) to uninfected RBCs. Rosetting is influenced by the host’s ABO blood group (Bg) and rosettes formed in BgA have previously been shown to be more resilient to disruption by heparin and shield the parasite derived surface antigens from antibodies. However, data on rosetting in weak BgA subgroups is scarce and based on investigations of relatively few donors.

Analysis of the potential for a malaria vaccine to reduce gaps in malaria intervention coverage

November 23, 2021 - 09:25 -- Open Access
Author(s): 
H. Juliette T. Unwin, Lazaro Mwandigha, Peter Winskill, Azra C. Ghani and Alexandra B. Hogan
Reference: 
Malaria Journal 2021 20:438, 17 November 2021

The RTS,S/AS01 malaria vaccine is currently being evaluated in a cluster-randomized pilot implementation programme in three African countries. This study seeks to identify whether vaccination could reach additional children who are at risk from malaria but do not currently have access to, or use, core malaria interventions.

Assessment of genetic diversity of Plasmodium falciparum circumsporozoite protein in Sudan: the RTS,S leading malaria vaccine candidate

November 23, 2021 - 09:20 -- Open Access
Author(s): 
Nouh Saad Mohamed, Hanadi AbdElbagi, Rihab Ali Omer, et al.
Reference: 
Malaria Journal 2021 20:436, 10 November 2021

The currently used malaria vaccine, RTS,S, is designed based on the Plasmodium falciparum circumsporozoite protein (PfCSP). The pfcsp gene, besides having different polymorphic patterns, can vary between P. falciparum isolates due to geographical origin and host immune response. Such aspects are essential when considering the deployment of the RTS,S vaccine in a certain region. Therefore, this study assessed the genetic diversity of P. falciparum in Sudan based on the pfcsp gene by investigating the diversity at the N-terminal, central repeat, and the C-terminal regions.

Absence of Plasmodium falciparum artemisinin resistance gene mutations eleven years after the adoption of artemisinin-based combination therapy in Nigeria

November 20, 2021 - 14:24 -- Open Access
Author(s): 
Moses Ikegbunam, Johnson A. Ojo, Kossiwa Kokou, Ugonna Morikwe, Chukwuemeka Nworu, Chibuzo Uba, Charles Esimone, Thirumalaisamy P. Velavan and Olusola Ojurongbe
Reference: 
Malaria Journal 2021 20:434, 10 November 2021

The occurrence of artemisinin resistance (ART)-associated polymorphism of Plasmodium falciparum K13-propeller (pfk13) gene before and after the introduction of artemisinin-based combination therapy (ACT) in two regions of Nigeria was investigated in this study. Regular surveillance is necessary to make a definite conclusion on the emergence and pattern of possible resistance to ART.

Efficacy of artesunate-amodiaquine and artemether-lumefantrine for uncomplicated Plasmodium falciparum malaria in Madagascar, 2018

November 20, 2021 - 14:11 -- Open Access
Author(s): 
Catherine M. Dentinger, Tovonahary Angelo Rakotomanga, C. Arsène Ratsimbasoa, et al.
Reference: 
Malaria Journal 2021 20:432, 3 November 2021

Since 2005, artemisinin-based combination therapy (ACT) has been recommended to treat uncomplicated falciparum malaria in Madagascar. Artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) are the first- and second-line treatments, respectively. A therapeutic efficacy study was conducted to assess ACT efficacy and molecular markers of anti-malarial resistance.

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