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red blood cell

Evolution of transcriptional control of antigenic variation and virulence in human and ape malaria parasites

July 14, 2021 - 10:02 -- Open Access
Author(s): 
Gross MR, Hsu R, Deitsch KW
Reference: 
BMC Ecol Evol. 2021 Jul 8;21(1):139

The most severe form of human malaria is caused by the protozoan parasite Plasmodium falciparum. This unicellular organism is a member of a subgenus of Plasmodium called the Laverania that infects apes, with P. falciparum being the only member that infects humans. The exceptional virulence of this species to humans can be largely attributed to a family of variant surface antigens placed by the parasites onto the surface of infected red blood cells that mediate adherence to the vascular endothelium. These proteins are encoded by a large, multicopy gene family called var, with each var gene encoding a different form of the protein. By changing which var gene is expressed, parasites avoid immune recognition, a process called antigenic variation that underlies the chronic nature of malaria infections.

Inter-study and time-dependent variability of metabolite abundance in cultured red blood cells

July 7, 2021 - 14:42 -- Open Access
Author(s): 
Shivendra G. Tewari, Krithika Rajaram, Russell P. Swift, Bobby Kwan, Jaques Reifman, Sean T. Prigge and Anders Wallqvist
Reference: 
Malaria Journal 2021 20:299, 2 July 2021

Cultured human red blood cells (RBCs) provide a powerful ex vivo assay platform to study blood-stage malaria infection and propagation. In recent years, high-resolution metabolomic methods have quantified hundreds of metabolites from parasite-infected RBC cultures under a variety of perturbations. In this context, the corresponding control samples of the uninfected culture systems can also be used to examine the effects of these perturbations on RBC metabolism itself and their dependence on blood donors (inter-study variations).

The Plasmodium falciparum Rh5 invasion protein complex reveals an excess of rare variant mutations

June 23, 2021 - 14:39 -- Open Access
Author(s): 
Leonard Ndwiga, Victor Osoti, Kevin Omondi Ochwedo, Kevin Wamae, Philip Bejon, Julian C. Rayner, George Githinji and Lynette Isabella Ochola-Oyier
Reference: 
Malaria Journal 2021 20:278, 23 June 2021

The invasion of the red blood cells by Plasmodium falciparum merozoites involves the interplay of several proteins that are also targets for vaccine development. The proteins PfRh5-PfRipr-PfCyRPA-Pfp113 assemble into a complex at the apical end of the merozoite and are together essential for erythrocyte invasion. They have also been shown to induce neutralizing antibodies and appear to be less polymorphic than other invasion-associated proteins, making them high priority blood-stage vaccine candidates. Using available whole genome sequencing data (WGS) and new capillary sequencing data (CS), this study describes the genetic polymorphism in the Rh5 complex in P. falciparum isolates obtained from Kilifi, Kenya.

Multiparametric biophysical profiling of red blood cells in malaria infection

June 15, 2021 - 15:00 -- Open Access
Author(s): 
Deshmukh SS, Shakya B, Chen A, Durmus NG, Greenhouse B, Egan ES, Demirci U
Reference: 
Commun Biol. 2021 Jun 8;4(1):697

Biophysical separation promises label-free, less-invasive methods to manipulate the diverse properties of live cells, such as density, magnetic susceptibility, and morphological characteristics. However, some cellular changes are so minute that they are undetectable by current methods. We developed a multiparametric cell-separation approach to profile cells with simultaneously changing density and magnetic susceptibility.

Plasmodium falciparum SURFIN(4.1) forms an intermediate complex with PTEX components and Pf113 during export to the red blood cell

April 29, 2021 - 07:36 -- Open Access
Author(s): 
Miyazaki S, Chitama BA, Kagaya W, Lucky AB, Zhu X, Yahata K, Morita M, Takashima E, Tsuboi T, Kaneko O
Reference: 
Parasitol Int. 2021 Apr 23:102358

Plasmodium falciparum malaria parasites export several hundred proteins to the cytoplasm of infected red blood cells (RBCs) to modify the cell environment suitable for their growth. A Plasmodium translocon of exported proteins (PTEX) is necessary for both soluble and integral membrane proteins to cross the parasitophorous vacuole (PV) membrane surrounding the parasite inside the RBC. However, the molecular composition of the translocation complex for integral membrane proteins is not fully characterized, especially at the parasite plasma membrane.

NOT Open Access | Characterisation of complexes formed by parasite proteins exported into the host cell compartment of Plasmodium falciparum infected red blood cells

March 30, 2021 - 14:13 -- NOT Open Access
Author(s): 
Jonsdottir TK, Counihan NA, Modak JK, Kouskousis B, Sanders PR, Gabriela M, Bullen HE, Crabb BS, de Koning-Ward TF, Gilson PR
Reference: 
Cell Microbiol. 2021 Mar 28:e13332

During its intraerythrocytic life cycle, the human malaria parasite Plasmodium falciparum supplements its nutritional requirements by scavenging substrates from the plasma through the new permeability pathways (NPPs) installed in the red blood cell (RBC) membrane. Parasite proteins of the RhopH complex: CLAG3, RhopH2, RhopH3, have been implicated in NPP activity.

NOT Open Access | A deep learning approach to the screening of malaria infection: Automated and rapid cell counting, object detection and instance segmentation using Mask R-CNN

March 2, 2021 - 11:38 -- NOT Open Access
Author(s): 
Loh R, Yong WX, Yapeter J, Subburaj K, Chandramohanadas R
Reference: 
Comput Med Imaging Graph. 2021 Mar;88:101845

Accurate and early diagnosis is critical to proper malaria treatment and hence death prevention. Several computer vision technologies have emerged in recent years as alternatives to traditional microscopy and rapid diagnostic tests. In this work, we used a deep learning model called Mask R-CNN that is trained on uninfected and Plasmodium falciparum-infected red blood cells.

Why it might be bad for brain cells to eat malaria parasites

March 2, 2021 - 11:36 -- Open Access
Author(s): 
Higgins MK
Reference: 
J Exp Med. 2021 Mar 1;218(3):e20202664

Malaria becomes very dangerous when it affects the brain. Cerebral malaria is caused when red blood cells, infected by the parasite Plasmodium falciparum, accumulate within tiny brain blood vessels, blocking blood flow (White et al., 2013).

Breakdown in membrane asymmetry regulation leads to monocyte recognition of P. falciparum-infected red blood cells

February 23, 2021 - 12:55 -- Open Access
Author(s): 
Fraser M, Jing W, Bröer S, Kurth F, Sander LE, Matuschewski K, Maier AG
Reference: 
PLoS Pathog. 2021 Feb 18;17(2):e1009259

The human malaria parasite Plasmodium falciparum relies on lipids to survive; this makes its lipid metabolism an attractive drug target. The lipid phosphatidylserine (PS) is usually confined to the inner leaflet of the red blood cell membrane (RBC) bilayer; however, some studies suggest that infection with the intracellular parasite results in the presence of this lipid in the RBC membrane outer leaflet, where it could act as a recognition signal to phagocytes. Here, we used fluorescent lipid analogues and probes to investigate the enzymatic reactions responsible for maintaining asymmetry between membrane leaflets, and found that in parasitised RBCs the maintenance of membrane asymmetry was partly disrupted, and PS was increased in the outer leaflet.

The malaria parasite sheddase SUB2 governs host red blood cell membrane sealing at invasion

December 9, 2020 - 07:45 -- Open Access
Author(s): 
Collins CR, Hackett F, Howell SA, Snijders AP, Russell MR, Collinson LM, Blackman MJ
Reference: 
Elife. 2020 Dec 8;9:e61121

Red blood cell (RBC) invasion by malaria merozoites involves formation of a parasitophorous vacuole into which the parasite moves. The vacuole membrane seals and pinches off behind the parasite through an unknown mechanism, enclosing the parasite within the RBC.

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