# Using Next Generation Chemiluminescent Probes to Improve the Plasmodium falciparum in vitro Parasite Reduction Ratio (PRR) Assay

## TL;DR

This paper introduces a faster, non-radioactive method to test antimalarial drugs using chemiluminescent probes, improving efficiency and accessibility.

## Contribution

A novel lacZ/β-galSENSOR-based PRR assay that reduces incubation time and avoids radioactive methods.

## Key findings

- The lacZ/β-galSENSOR method reliably detects viable parasites in 7 days with accurate pharmacodynamic parameters.
- The [3H]-hypoxanthine method overestimates drug activity and fails with the shortened protocol.
- The new assay offers higher throughput and lower equipment needs than existing methods.

## Abstract

Malaria remains a major global health threat, and the
emergence
of partial artemisinin resistance challenges current treatment regimens.
Reliable antimalarial screening assays are therefore essential for
identifying new drug candidates. The parasite reduction ratio (PRR)
assay provides valuable pharmacodynamic insights but is limited by
its labor-intensive, 14- to 28-day incubation period. We developed
an optimized PRR assay protocol using the highly sensitive chemiluminescence-based lacZ/β-galSENSOR readout, reducing assay
incubation duration to 7 days while maintaining informative pharmacodynamic
parameters, including lag phase, parasite clearance time, parasite
reduction ratio, and maximum killing effect. In contrast, the [3H]-hypoxanthine incorporation method failed to detect viable
parasites reliably and consistently overestimated drug activity with
the shortened protocol. This novel lacZ/β-galSENSOR PRR assay enables laboratories without access to radioactive
facilities to evaluate antimalarial compounds efficiently, providing
robust time–killing profiles with greater convenience, higher
throughput, and lower equipment requirements than existing readout
methods.