Background Plasmodium ovale is widely distributed across tropical regions and has two closely related but distinct species, namely P. ovale curtisi and P. ovale wallikeri . Combining genetic characterization with the immunogenicity of merozoite surface protein-8 (MSP-8) supports considering MSP-8 as a candidate target for blood-stage vaccines against malaria. However, no previous studies have focused on characterizing the genetic diversity and immunogenicity of PoMSP-8. Methods Blood samples were collected from 42 patients infected with P. ovale . The patients were migrant workers returning to the Jiangsu Province from Africa; genomic DNA was extracted from their blood samples for sequencing and protein expression. The recombinant PoMSP-8 (rPoMSP-8) proteins were expressed and purified to assess their immune responses in BALB/c mice. Results The sequences of the P. ovale curtisi and P. ovale wallikeri msp8 genes were completely conserved in each isolate. The rPoMSP-8 proteins were successfully expressed and purified as ~70 kDa proteins. Antibodies raised against rPoMSP-8 in mice showed appropriate immunoreactivity, as evidenced by immunoblotting. These specific antibodies were detected at day 7 post-immunization, and their levels increased throughout the whole immunization period. rPoMSP-8-raised antibodies had high endpoint titers (1:5,120,000) and high avidity (PocMSP-8: 94.84%, PowMSP-8: 92.69%). Cross-reactivity between rPocMSP-8 and rPowMSP-8 was observed with each anti-PoMSP8-specific antibody. Conclusions Remarkable conservation and high immunogenicity was observed in both rPoMSP-8s. Intriguingly, cross-reaction between rPocMSP-8 and rPowMSP-8 was detected, suggesting that a single PoMSP8-based construction might be applicable for both species. Electronic supplementary material The online version of this article (10.1186/s13071-019-3412-0) contains supplementary material, which is available to authorized users.
【저자키워드】 immunogenicity, cross-reactivity, conservation, Plasmodium ovale, MSP-8,