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knowlesi

NOT Open Access | Exploring Heteroaromatic Rings as a Replacement for the Labile Amide of Antiplasmodial Pantothenamides

April 6, 2021 - 14:29 -- NOT Open Access
Author(s): 
Guan J, Spry C, Auclair K, et al.
Reference: 
J Med Chem. 2021 Apr 1

Malaria-causing Plasmodium parasites are developing resistance to antimalarial drugs, providing the impetus for new antiplasmodials. Although pantothenamides show potent antiplasmodial activity, hydrolysis by pantetheinases/vanins present in blood rapidly inactivates them. We herein report the facile synthesis and biological activity of a small library of pantothenamide analogues in which the labile amide group is replaced with a heteroaromatic ring.

Reduced circulating dendritic cells in acute Plasmodium knowlesi and Plasmodium falciparum malaria despite elevated plasma Flt3 ligand levels

February 17, 2021 - 09:15 -- Open Access
Author(s): 
Jessica R. Loughland, Tonia Woodberry, Gabriela Minigo, et al.
Reference: 
Malaria Journal 2021 20:97, 16 February 2021

Plasmodium falciparum malaria increases plasma levels of the cytokine Fms-like tyrosine kinase 3 ligand (Flt3L), a haematopoietic factor associated with dendritic cell (DC) expansion. It is unknown if the zoonotic parasite Plasmodium knowlesi impacts Flt3L or DC in human malaria. This study investigated circulating DC and Flt3L associations in adult malaria and in submicroscopic experimental infection.

Plasmodium-a brief introduction to the parasites causing human malaria and their basic biology

January 16, 2021 - 09:54 -- Open Access
Author(s): 
Sato S
Reference: 
J Physiol Anthropol. 2021 Jan 7;40(1):1

Malaria is one of the most devastating infectious diseases of humans. It is problematic clinically and economically as it prevails in poorer countries and regions, strongly hindering socioeconomic development. The causative agents of malaria are unicellular protozoan parasites belonging to the genus Plasmodium. These parasites infect not only humans but also other vertebrates, from reptiles and birds to mammals. To date, over 200 species of Plasmodium have been formally described, and each species infects a certain range of hosts.

Malaria parasites in macaques in Thailand: stump-tailed macaques (Macaca arctoides) are new natural hosts for Plasmodium knowlesi, Plasmodium inui, Plasmodium coatneyi and Plasmodium fieldi

October 6, 2020 - 12:39 -- Open Access
Author(s): 
Wirasak Fungfuang, Chanya Udom, Daraka Tongthainan, Khamisah Abdul Kadir and Balbir Singh
Reference: 
Malaria Journal 2020 19:350, 1 October 2020

Certain species of macaques are natural hosts of Plasmodium knowlesi and Plasmodium cynomolgi, which can both cause malaria in humans, and Plasmodium inui, which can be experimentally transmitted to humans. A significant number of zoonotic malaria cases have been reported in humans throughout Southeast Asia, including Thailand. There have been only two studies undertaken in Thailand to identify malaria parasites in non-human primates in 6 provinces. The objective of this study was to determine the prevalence of P. knowlesi, P. cynomolgi, P. inui, Plasmodium coatneyi and Plasmodium fieldi in non-human primates from 4 new locations in Thailand.

Quantification of Plasmodium knowlesi versus Plasmodium falciparum in the rhesus liver: implications for malaria vaccine studies in rhesus models

September 1, 2020 - 10:12 -- Open Access
Author(s): 
Melanie J. Shears, Annette M. Seilie, B. Kim Lee Sim, Stephen L. Hoffman and Sean C. Murphy
Reference: 
Malaria Journal 2020 19:313, 31 August 2020

Rhesus macaques are valuable pre-clinical models for malaria vaccine development. The Plasmodium knowlesi/rhesus and Plasmodium falciparum/rhesus models are two established platforms for malaria vaccine testing, and both have previously been used to assess live-attenuated sporozoite vaccines. However, there is evidence that the susceptibility of the rhesus liver to P. knowlesi versus P. falciparum sporozoites likely differs, potentially complicating comparisons between these two platforms.

Comparative evaluation of two commercial real-time PCR kits (QuantiFast™ and abTES™) for the detection of Plasmodium knowlesi and other Plasmodium species in Sabah, Malaysia

September 1, 2020 - 09:48 -- Open Access
Author(s): 
Nor Afizah Nuin, Angelica F. Tan, Matthew J. Grigg, et al.
Reference: 
Malaria Journal 2020 19:306, 27 August 2020

The monkey parasite Plasmodium knowlesi is an emerging public health issue in Southeast Asia. In Sabah, Malaysia, P. knowlesi is now the dominant cause of human malaria. Molecular detection methods for P. knowlesi are essential for accurate diagnosis and in monitoring progress towards malaria elimination of other Plasmodium species. However, recent commercially available PCR malaria kits have unpublished P. knowlesi gene targets or have not been evaluated against clinical samples.

Naturally Acquired Human Plasmodium cynomolgi and P. knowlesi Infections, Malaysian Borneo

August 4, 2020 - 15:27 -- Open Access
Author(s): 
Raja TN, Hu TH, Kadir KA, Mohamad DSA, Rosli N, Wong LL, Hii KC, Simon Divis PC, Singh B
Reference: 
Emerg Infect Dis. 2020 Aug; 26(8):1801-1809

To monitor the incidence of Plasmodium knowlesi infections and determine whether other simian malaria parasites are being transmitted to humans, we examined 1,047 blood samples from patients with malaria at Kapit Hospital in Kapit, Malaysia, during June 24, 2013-December 31, 2017. Using nested PCR assays, we found 845 (80.6%) patients had either P. knowlesi monoinfection (n = 815) or co-infection with other Plasmodium species (n = 30).

Use of a highly specific kinase inhibitor for rapid, simple and precise synchronization of Plasmodium falciparum and Plasmodium knowlesi asexual blood-stage parasites

July 20, 2020 - 15:15 -- Open Access
Author(s): 
Ressurreição M, Thomas JA, Nofal SD, Flueck C, Moon RW, Baker DA, van Ooij C.
Reference: 
PLoS ONE 15(7): e0235798

During the course of the asexual erythrocytic stage of development, Plasmodium spp. parasites undergo a series of morphological changes and induce alterations in the host cell. At the end of this stage, the parasites egress from the infected cell, after which the progeny invade a new host cell. These processes are rapid and occur in a time-dependent manner.

Efficient synchronization of Plasmodium knowlesi in vitro cultures using guanidine hydrochloride

April 29, 2019 - 13:17 -- Open Access
Author(s): 
Sutharinee Ngernna, Anongruk Chim-ong, Wanlapa Roobsoong, Jetsumon Sattabongkot, Liwang Cui and Wang Nguitragool
Reference: 
Malaria Journal 2019 18:148, 25 April 2019

Long-term in vitro culture of blood stage Plasmodium parasites invariably leads to asynchronous parasite development. The most often used technique to synchronize Plasmodium falciparum culture is sorbitol treatment, which differentially induces osmotic lysis of trophozoite- and schizont-infected red blood cells due to presence of the new permeation pathways in the membranes of these cells. However, sorbitol treatment does not work well when used to synchronize the culture-adapted Plasmodium knowlesi A1-H.1 line.

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Plasmodium knowlesi and other malaria parasites in long-tailed macaques from the Philippines

April 29, 2019 - 13:15 -- Open Access
Author(s): 
Lief Erikson Gamalo, Judeline Dimalibot, Khamisah Abdul Kadir, Balbir Singh and Vachel Gay Paller
Reference: 
Malaria Journal 2019 18:147, 24 April 2019

Macaca fascicularis (long-tailed macaque) is the most widespread species of macaque in Southeast Asia and the only species of monkey found naturally in the Philippines. The species is the natural host for the zoonotic malaria species, Plasmodium knowlesi and Plasmodium cynomolgi and for the potentially zoonotic species, Plasmodium inui. Moreover, other Plasmodium species such as Plasmodium coatneyi and Plasmodium fieldi are also natural parasites of M. fascicularis. The aims of this study were to identify and determine the prevalence of Plasmodium species infecting wild and captive long-tailed macaques from the Philippines.

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