Genotyping and Characterizing Plasmodium falciparum to Reveal Genetic Diversity and Multiplicity of Infection by Merozoite Surface Proteins 1 and 2 (msp-1 and msp-2) and Glutamate-Rich Protein (glurp) Genes

Resistance to current antimalarial drugs is steadily increasing, and new drugs are required.
Drug efficacy trials remain the gold standard to assess the effectiveness of a given drug. TheWorld
Health Organization (WHO)’s recommendation for the optimal duration of follow-up for assessing
antimalarial efficacy is a minimum of 28 days. However, assessing antimalarial drug efficacy in highly
endemic regions can be challenging due to the potential risks of acquiring a new infection in the
follow-up period, and thus, it may underestimate the efficacy of the given drugs. A new treatment
should be introduced if treatment failure rates exceed 10%. Overestimation occurs as a result of
retaining a drug with a clinical efficacy of less than 90% with increases in morbidity and mortality,
while underestimation may occur due to a misclassification of new infections as treatment failures
with tremendous clinical and economic implications. Therefore, molecular genotyping is necessary to
distinguish true new infections from treatment failures to ensure accuracy in determining antimalarial
efficacy. There are three genetic markers that are commonly used in antimalarial efficiency trials to
discriminate between treatment failures and new infections. These include merozoite surface protein
1 (msp-1), merozoite surface protein 2 (msp-2), and glutamate-rich protein (glurp). The genotyping
of P. falciparum by nested polymerase chain reaction (n-PCR) targeting these markers is discussed
with the inherent limitations and uncertainties associated with the PCR technique and limitations
enforced by the parasite’s biology itself.