Background: Vaccine antigens targeting specific P. falciparum
parasite stages are under pre-clinical and clinical development. It
seems plausible that vaccine with multiple specificities will offer
higher protection. With this hypothesis, we exploited the
SpyTag/SpyCatcher conjugation system to make a, post expression, dual
antigen conjugate vaccine, comprising two clinically tested antigen
candidates (CSP and VAR2CSA). Methods: The DBL1x-DBL2x-ID2a region of
VAR2CSA was genetically fused with SpyTag at N-terminus. The
full-length CSP antigen was genetically fused to C-terminal SpyCatcher
peptide. The covalent interaction between SpyTag/SpyCatcher enables the
formation of DBL1x-DBL2x-ID2a:CSP conjugate vaccine. Immunogenicity and
quality of antibody responses induced by the conjugate vaccine, as well
as a control CSP-SpyCatcher vaccine, was tested in BALB/c mice.
Results: Serum samples obtained from mice immunized with the conjugate
vaccine were able to recognize both untagged DBL1x-DBL2x-ID2a as well
as CSP antigen. Moreover, the geometric mean anti-CSP antibody titer
was 1.9-fold higher in serum (at day 35 and 55 post-first immunization)
from mice immunized with the conjugate vaccine, as compared to mice
receiving the control vaccine. Conclusion: The data obtained in this
study serves as proof-of-concept for the simultaneous induction of
antibodies directed against individual antigen components in a dual
stage anti-malaria vaccine