Study to determine the rate of kill of anti-leishmanial drugs using a novel bioluminescence-based assay

Freakley, Abigail Leah

Abstract

Leishmaniasis is a neglected tropical disease associated with poverty, deprived socio-economic settings and population displacement, primarily due to conflict. The causative agent are species of Leishmania parasites that are transmitted by sand flies. It is a disease that affects millions every year and manifests into three primary forms; cutaneous, mucocutaneous and visceral leishmaniasis. Each of these forms are extremely debilitating to the everyday life of those living with leishmaniasis. The current drugs used are re-purposed treatments that are far from ideal. Emerging reports of resistance, poor patient cooperation as a result of long treatment regimens and highly toxic side effects are indicative of essential improvements needed.
This thesis focuses on using a transgenic Leishmania cell line in a novel bioluminescence-based assay to determine the rate of kill of four current anti-leishmanial drugs: amphotericin B, miltefosine, pentamidine and potassium antimonyl tartrate. This axenic in vitro assay is studied to address the pharmacodynamic gap in the early drug discovery process and to evaluate the use of a novel technique and its potential in the development of more dynamic and predictive assays. At 3-fold the EC50 concentration, amphotericin B had completely eliminated all viable parasites within 4 hours, demonstrating that it is a fast-acting drug. Miltefosine on the other hand, failed to reduce total parasite viability after 72-hour exposure and we therefore characterised miltefosine as slow-acting. Pentamidine and potassium antimonyl tartrate exhibited an intermediate rate of kill, reaching maximal effect on parasite growth within 72 hours at 9 x the EC50. The bioluminescence-based assay provides a dynamic reporter for parasite viability and exciting potential for fast, sensitive results in early drug screening as shown by the ability to quickly discriminate between fast- and slow- acting compounds. Addressing and identifying this research gap can aid with treatment regimens and dosage improvements of current and novel drug treatments for leishmaniasis.

Citation

Freakley, A. L. (2023). Study to determine the rate of kill of anti-leishmanial drugs using a novel bioluminescence-based assay. (Thesis). Keele University

• Thesis Type: Thesis
• Deposit Date: Jul 19, 2023
• Publicly Available Date: Jul 19, 2023
• Award Date: 2023-06