Novel Nona-Repeat in Plasmodium ovale curtisi Circumsporozoite Protein Circulating in Cameroon

Circumsporozoite protein (CSP) is the primary component of two malaria vaccines that have been validated by World Health Organisation. However, these vaccines do not include antigens from non-falciparum species, which should also be considered. The csp gene was amplified and sequenced in 14 Plasmodium ovale cuitisi (Poc) isolates from Cameroon. The C and N-terminal regions showed perfect conservation, while the central region showed repeated motifs of nine amino acids. Interestingly, in addition to nano-repeat motifs reported in the literature, a new motif (QSEGNPPAP) was observed in four samples, resulting in haplotype combinations that can affect the antigenicity of protein and therefore should be taken into account when designing a CSP-based vaccine against Poc malaria.