Das, G. | Search bioRxiv

bioRxiv2021

Targeting the artemisinin resistant malaria by repositioning of the anti-Hepatitis C Virus drug Alisporivir

The rapid emergence of P. falciparum-resistant strains raises an urgent need to find new antimalarial drug candidates. This study reports the rational repositioning of the anti-Hepatitis C Virus drug, Alisporivir, a non-immunosuppressive analog of cyclosporin A (CsA) against multiple, drug-resistant strains of P. falciparum. Alisporivir being non-hemolytic has been proven to be a better drug than CsA. Indeed, our study also demonstrated the same. Alisporivir inhibited chloroquine-sensitive parasite growth with an IC50 of 196.6nM. Alisporivir also inhibited the growth of chloroquine-resistant parasites with an IC50 of 422.1nM. Alisporivir exhibited, anti-malarial activity in in vivo. Further, we exploited the Cyclophilins targeting potential of Alisporivir against artemisinin-resistant malaria parasite owing to the fact that PfCyP-19B is one of the genes that is overexpressed in artemisinin-resistant parasite revealed by a population transcriptomic study. Our semiquantitative real-time transcript and immunofluorescence analysis confirmed the overexpression of PfCyP-19B in Artemisinin-resistant P. falciparum (PfKelch13R539T). Artemisinin resistance is attributed to slow clearance of ring stage parasites. Ring survival assay (RSA) is designed to access the potency of compounds on these dormant slow clearing parasites leading to drug resistance. Thus, the potency of Alisporivir against PfKelch13R539T was evaluated by RSA. A 2.5-fold decrease in parasite survival was detected with Alisporivir. Further, combination of Alisporivir with DHA found to potentiate the efficacy of DHA by 4.55-fold. These results support the hypothesis that targeting of resistance mechanism is a potential approach to deal with resistant parasite. Overall, this study demonstrates the rational reposition of Alisporivir against resistant malaria resistance.

microbiology↗

bioRxiv2020

Enhanced odour-associated memory performance with a Y-maze assembly in Drosophila

The neural basis of behaviour is identified by systematically disrupting the activity of specific neurons and screening for loss in phenotype. Robust, high-scoring behavioural assays are thus necessary for identifying the neural circuits of novel behaviours. Here, we report the design and use of a Y-maze based classical olfactory learning and memory assay in Drosophila. Appetitive memory scores in our Y-mazes are considerably better and longer-lasting than that from a commonly used T-maze design. We found that the mechanism that traps flies in their choice of an odour is mainly responsible for the improving scores in the Y-mazes. Using Y-mazes, we could assay significant 24 h gustatory aversive memories in flies. These aversive memories are susceptible to protein synthesis inhibitor cycloheximide (CXM) and therefore embodies long-term memory (LTM). When anaesthesia resistant memory (ARM) deficient radish mutant flies are trained with dry sucrose, 24 h memory is severely disrupted. However, when we trained with 2 M sucrose-agar and tested in Y-mazes, radish mutants exhibited a residual 24 appetitive memory. This memory is not ARM, and we show that it is not CXM sensitive LTM either. It could be a third form of appetitive consolidated memory in flies. The Y-maze assembly described here is particularly sensitive and will thus enable the study of new memory phenotypes in Drosophila.

neuroscience↗