Genetic polymorphism of Plasmodium falciparum using merozoite surface proteins 1 and 2 (msp-1 and msp-2) genes in Oveng and Mintom, South region of Cameroon

Malaria remains a critical public health issue in Cameroon, where Plasmodium falciparum is the predominant species responsible for severe clinical cases. Investigating the genetic diversity and multiplicity of infection (MOI) of P. falciparum is essential for understanding transmission dynamics, immune evasion, and the effectiveness of control strategies. This study aimed to characterize the allelic polymorphism and MOI of P. falciparum isolates collected in Oveng and Mintom, two selected health areas within the Dja et Lobo Division, a malaria-endemic area in southern Cameroon. Genomic DNA was extracted from dried blood spots collected from infected individuals. P. falciparum detection and species confirmation were performed using a multiplex polymerase chain reaction (PCR). Genotyping of msp1 allelic families (KI, MAD20, and RO33) and msp2 allelic families (FC27, 3D7) was conducted via nested PCR. Fragment analysis was used to determine allelic variants and estimate MOI. A total of 315 P. falciparum isolates were successfully amplified and genotyped. For msp1, 12 distinct alleles were identified (3 for KI, 7 for MAD20, and 2 for RO33), with fragment sizes ranging from 172 to 300 bp. For msp2, 28 alleles were detected (14 for each FC27 and 3D7allelic families), with fragment sizes ranging from 200 to 800 bp. For msp2, the FC27 allelic family was the most prevalent (100%), followed by 3D7 (98.4%). For msp1, K1 was detected in 87.8% of samples, while MAD20 and RO33 were present in 75.2% and 74.9% of isolates, respectively. The number of clones per infection ranged from 1 to 7, with 99% of samples exhibiting polyclonal infections. The mean MOI was significantly higher for msp2 compared to msp1 (4.85 vs. 2.40; p < 0.05). Expected heterozygosity was 0.83 for msp1 and 0.98 for msp2, indicating high genetic diversity. The observed high allelic diversity and elevated MOI among P. falciparum isolates suggest intense malaria transmission in the study areas. These findings underscore the need to strengthen local malaria control interventions and provide valuable baseline data for future surveillance and vaccine development efforts.