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Evolutionary Biology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
The demands imposed on the same parasite in different hosts can have some interesting consequences, as pointed out by the following artificial situation. Some strains of the rodent parasite Plasmodium berghei that are routinely passaged by syringe (and not mosquitoes) to new hosts are resistant to the antimalarial compound atovaquone, conferring on them an ability to survive exposure to this drug when in the blood of mice. The basis for resistance lies in mutations in the cytochrome b gene (cytB) of the mitochondrion. These mitochondria nonetheless retain a low but necessary activity for bloodstream parasites. However, if these parasites are allowed to be transmitted by mosquitoes in which demands for oxidative respiration for P. berghei are much higher, the atovaquone-resistant mutants perish because of their mutated cytochrome b proteins. One lesson here is that if resistance to atovaquone facilitated by cytochrome b mutants were to arise in a human host, the mutant parasites would likely die in the mosquito vector, thus slowing or altogether preventing the spread of cytB-based atovaquone resistance.
Antiprotozoal Effects of Wild Plants
Published in Mahendra Rai, Shandesh Bhattarai, Chistiane M. Feitosa, Ethnopharmacology of Wild Plants, 2021
Muhammad Subbayyal Akram, Rao Zahid Abbas, José L. Martinez
Hintonia belongs to family Rubiaceace, mostly found in the forests of Mexico. Hintonia latiflora (Figure 7.2) is proven to be effective against Plasmodium berghei. Ethyl acetate extraction of H. latifolra stem bark and High-performance liquid chromatography reveals the presence of two compounds which are 5-O-β-D-glucopyranosyl-7,40-dimethoxy-30-hydroxy-4-phenylcoumarin and 5-O-β-D-glucopyranosyl-7-methoxy-30,40-dihydroxy-4-phenylcoumarin. The effectiveness of these molecules is tested in vitro that results in 70.8% suppression in the development of schizonts when its extract was used by the dosage of 40 mg/kg in in vitro trials. Both molecules are proven to be effective at IC50, which are 24.7 and 25.9 μm against P. berghei, especially in schizonts development in in vitro trials (Argotte-Ramos et al. 2006).
Subfamily Bombacoideae
Published in Mahendra Rai, Shandesh Bhattarai, Chistiane M. Feitosa, Wild Plants, 2020
Mariam I. Gamal El-Din, Fadia S. Youssef, Mohamed L. Ashour, Omayma A. Eldahshan, Abdel Nasser B. Singab
The aqueous extract of Bombax buonopozense stem bark was determined for in vivo antiplasmodial effect in mice with infection triggered by chloroquine sensitive Plasmodium berghei. The extract at doses (100–400 mg/kg) exhibited dose-dependent activity with p < 0.05 versus the parasite in suppressive and curative tests (Iwuanyanwu et al. 2012). The methanol extract of B. buonopozense leaves also proved to possess significant in vivo antiplasmodial activity at the doses of 200–600 mg/kg. The activity was evaluated versus chloroquine sensitive Plasmodium berghei in mice through early and occurred infections. The established LD50 of the extract was found to be greater than 5, 000 mg/kg (Akuodor et al. 2012b).
An ex vivo system for investigation of Plasmodium berghei invasion of the salivary gland of Anopheles stephensi mosquitoes
Published in Pathogens and Global Health, 2023
Mai I. Hussien, Belal A. Soliman, Maha K. Tewfick, David A. O’Brochta
As one of first attempts toward investigating the sporozoites invasion of An. stephensi salivary glands and to visualize the molecular developmental differences between sporozoites obtained from mature oocysts and sporozoites obtained from salivary glands, an ex- salivary gland vivo system is used which could render this complex biological event amenable to experimental analysis. Here, while attempting to establish a workable ex vivo culture system to study sporozoite/salivary gland interactions we discovered that coculturing of salivary glands of Anopheles stephensi and Plasmodium berghei sporozoites stimulated the rapid precocious maturation of the sporozoites in the absence of salivary gland invasion into parasites resembling those that would be found within salivary glands. Salivary gland invasion by sporozoites results in the parasites gaining their full ability to infect a vertebrate host while losing the ability to invade mosquito salivary glands[14]. Preventing this precocious maturation will be important in the successful development of an ex vivo model system for investigating the mosquito phases of Plasmodium development.
Role of platelets and megakaryocytes in adaptive immunity
Published in Platelets, 2021
Genevieve Marcoux, Audrée Laroche, Jenifer Espinoza Romero, Eric Boilard
While these findings point to a potential use for platelets in a cell-based vaccine, this hypothesis was tested with an actual pathogen, Plasmodium berghei, the parasite that causes malaria. Using a Plasmodium berghei parasite transgenic for the C-terminal amino acids 150–368 of OVA (Pba-OVA), it was shown that platelets, via their MHC I, are able to acquire and present PbA-OVA-derived antigens to generate protective T cells [64]. Together, these observations demonstrate that platelets are capable of antigen processing and presentation (Figure 1). While platelets can internalize pathogens other than Plasmodium berghei, such as dengue virus, influenza virus and HIV [67,70] through phagocytosis or endocytosis, they also increase bacterial clearance in septic mice [71]. However, it remains to be established whether processed microbial antigens can be presented by MHC I molecules on activated platelets to fulfill a role in adaptive immunity against these pathogens.
New peptide derived antimalaria and antimicrobial agents bearing sulphonamide moiety
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
D. I. Ugwuja, U. C. Okoro, S. S. Soman, R. Soni, S. N. Okafor, D. I. Ugwu
Experimental Design and Treatment of Mice. Methods of Peter et al.30 and Kalra et al.31 for antiplasmodial assay against Plasmodium berghei infection in mice with some modifications were employed. About eighty infected mice were randomly divided into five groups, each having fourteen mice. The inoculum was prepared from a donor mouse with rising parasitemia of 60.42%. After 7 days of infection, animals begin to receive treatment (100 and 200 mg/kg b wt.) of the synthesized compounds (7a–7n) for 12 days with constant check of the percentage of parasitemia after a 4-day interval. Artemisinin (100 and 200 mg/kg body weight.) was given to the other mice in group three as positive control, group four was not treated and group five was not infected. All the compounds and the drugs were given orally by using a standard intragastric tube. For all parasitemia determination, blood samples were collected from tail snip of each mouse and thin smears prepared and stained with 10% Giemsa solution. The uniform fields of each stained slide (for each mouse) were examined under microscope with an oil immersion objective of 100X magnification power and average percent of parasitemia was determined.