Prime-boost strategy for vaccine development against both Plasmodium vivax and P. falciparum using MSP-1₁₉ as antigen

Background

Both antibodies and effector T cells appear to play important roles in the protection against P. vivax and P. falciparum infection. However, the partial protective immunity induced by vaccination with recombinant C-terminal region of merozoite surface protein (MSP-1₁₉) is mediated largely by antibodies ([1, 2]). Therefore, the objective of the present study was to evaluate, when PvMSP-1₁₉ and PfMSP-1₁₉ antigens were administered as combination at a single site in mice by using different immunization strategies (DNA/DNA, DNA/rprotein, rprotein/rprotein). We found that mice immunized with both recombinant antigens alone and in combination using heterologous prime-boost strategies (prime with DNA 100 ng and boost with recombinant protein 35 μg) lead to induced substantial levels of MSP-1₁₉ specif c IgG1, IgG2a and IgG2b (a mixed Th1/Th2 type) antibodies as measured by ELISA (Figure 1). In addition, both antigens significantly increased IFNγ responses in mice immunized with both antigens in combination using prime-boost strategy (Figure 2). rPfMSP-1₁₉ when combined with rPvMSP-1₁₉ was not affects antibodies or IFNγ and IL-10 responses in prime-boost strategy.

Figure 1

(abstract P64). Antibody responses to rPvMSP-1₁₉(a) and rPfMSP-1₁₉(b) in immunized mice.

Figure 2

(abstract P64). IFNγ responses to rPvMSP-1₁₉(a) and rPfMSP-1₁₉(b) in immunized mice.

Conclusion

The present results are encouraging to develop a multispecies human malaria vaccine against asexual blood stage of P. vivax and P. falciparum. Further study is needed to evaluate the protective efficacy of this vaccine in non-human primates.