IntroductionThe decline in protective antibody titers and efficacy over time of the circumsporozoite protein (CSP)-based RTS,S/AS01 and R21/Matrix-M vaccines highlights the need for improved vaccines. Sporozoite microneme protein essential for cell traversal-1 (SPECT-1) is a conserved Plasmodium falciparum (Pf) antigen that plays a key role in parasite movements while traversing host cells.
Targeting SPECT-1 as an addition to the CSP in the same vaccine may enhance immune response and protection.MethodsWe engineered a series of recombinant Hepatitis B surface antigen (HBsAg) virus-like particles (VLPs) displaying PfSPECT-1 alone or in combination with NANP repeats and C-terminal region of PfCSP. These monovalent and bivalent VLP vaccine candidates were evaluated alongside R21 in a prime-boost regimen which was followed by challenge with transgenic P.
berghei parasite expressing the same P. falciparum antigens.
We also assessed the quality of the antibody response following vaccination. Based on the antibody titers and protective efficacy, one bivalent VLP construct was selected for further evaluation with different adjuvant formulations.ResultsAll bivalent VLPs formed to display antigenic epitopes that were accessible to antigen-specific antibodies.
Frontiers in Immunology published a clinical update in Infectious Disease on 14 May 2026.
The item focuses on Bivalent virus-like particles expressing SPECT1 and CSP trigger pre-erythrocytic malaria immunity and protect against transgenic Plasmodium falciparum sporozoite challenge in mice.
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