Evaluation of central repeats and haplotype on Plasmodium falciparum circumsporozoite gene in isolates obtained from Ore, Osun State, Nigeria

Title : Evaluation of central repeats and haplotype on Plasmodium falciparum circumsporozoite gene in isolates obtained from Ore, Osun State, Nigeria

Abstract:

The global burden of malaria persists, prompting the approval of the RTS, S vaccine for widespread use in children by the WHO in 2021. However, the efficacy of this vaccine is influenced by genetic variations in the Plasmodium falciparum circumsporozoite protein (PfCSP), particularly within African populations where malaria remains endemic. This study aims to assess the potential impact of PfCSP diversity on the future deployment of the RTS,S vaccine in Nigeria. The PfCSP central repeat prevalence and haplotypes were evaluated in asymptomatic schoolchildren aged 5-17 in Ore town, Osun State, Nigeria, using rapid diagnostic tests to confirm Plasmodium falciparum infection in blood samples from 75 schoolchildren. Genomic DNA was extracted from dried blood spots, and Nested PCR amplification targeted the central repeat region of the CSP gene. The Sanger sequencing technique was used to sequence the amplicons. Overall, 50 of the 75 samples considered for this study were successfully amplified and sequenced. The Geneious Prime program was used to analyze polymorphic characteristics, revealing the presence of three predominant haplotypes: NANP, NVDP, and NPDP, with NANP being the most prevalent in 50 out of the 75 samples. The number of NANP repeats ranged from 1 to 35, while NVDP ranged from 1 to 4, with only one variant of NPDP reported. Findings from this study highlight the polymorphic nature of the PfCSP central repeat region in Plasmodium falciparum isolates among asymptomatic children in Ore, Osun State. This diversity may predict innate reduced effectiveness of the RTS,S vaccine when deployed in Nigeria. Understanding PfCSP polymorphisms is crucial for optimizing malaria control strategies and vaccine development efforts in endemic regions.

Keywords: Polymorphism, RTS,S vaccine, Central repeats/Haplotypes, Circumsporozoite protein, Plasmodium falciparum.

Biography:

Olafusi Celestina Oluwaseun is a Biochemist and Molecular Biologist specializing in genomics, bioinformatics, and computational biology. She is a doctoral researcher in Biochemistry at Covenant University, Nigeria, investigating the role of salivary gland microbiota in Plasmodium falciparum development using integrated transcriptomics and machine learning. She earned an MSc in Molecular Biology and Genomics (Distinction) from Redeemer’s University and a First- Class BSc in Biochemistry from the University of Medical Sciences, Ondo. Currently an Assistant Lecturer at UNIMED, she has published widely in peer-reviewed journals and received several awards, including Overall Best Graduating Student.