Immunogenic profile of a plant-produced nonavalent African horse sickness viral protein 2 (VP2) vaccine in IFNAR-/- mice.
Authors: O'Kennedy Martha M, Roth Robyn, Ebersohn Karen, du Plessis Lissinda H, Mamputha Sipho, Rutkowska Daria A, du Preez Ilse, Verschoor Jan A, Lemmer Yolandy
Journal: PloS one
Summary
# Editorial Summary Researchers evaluated a plant-produced nonavalent vaccine candidate containing viral protein 2 (VP2) from all nine serotypes of African horse sickness virus (AHSV), addressing a critical gap in the current vaccine landscape where existing live attenuated vaccines protect only against limited serotypes and carry safety concerns in immunocompromised horses. Using IFNAR-/- mice as a preclinical model, two formulation strategies were tested: a combination of virus-like particles and soluble VP2, and soluble VP2 alone, both administered as pentavalent doses totalling 5 μg per serotype, with performance benchmarked against the commercially available live attenuated vaccine. The adjuvanted nonavalent VP2 vaccine delivered via prime-boost immunisation elicited neutralising antibody titres of 1:320 against all nine serotypes—a threshold previously established as protective in this mouse model—whilst also generating both Th2 and Th1 T cell responses indicative of robust humoral and cell-mediated memory immunity. The plant-produced VP2 proteins were confirmed as antigenically distinct across serotypes using LC-MS/MS and ELISA, demonstrating the feasibility of maintaining serotype-specific immunogenicity within a single formulation. These findings represent a meaningful step toward a truly multivalent vaccine that could streamline protection protocols in endemic regions and provide flexible mono-, bi- or nonavalent configurations suited to regional disease epidemiology, though efficacy and safety studies in horses are now essential before clinical application.
Read the full abstract on PubMed
Practical Takeaways
- •A plant-produced nonavalent vaccine covering all 9 AHSV serotypes could eventually provide broader protection in endemic regions without requiring multiple separate vaccines
- •The prime-boost vaccination strategy appears necessary to achieve protective antibody titres; single-dose vaccination was insufficient
- •This preclinical work supports progression to efficacy testing in horses; practical application in equine herds remains years away
Key Findings
- •Plant-produced nonavalent VP2 vaccine elicited neutralising antibody titres of 1:320 against all 9 AHSV serotypes using prime-boost strategy in IFNAR-/- mice
- •Adjuvanted multivalent VP2 vaccine induced both Th1 and Th2 memory T cell responses, indicating both humoral and cell-mediated immunity
- •Plant-produced VP2 vaccine performed favourably compared to commercially available live attenuated AHS vaccine in immunogenicity
- •VP2 proteins from each of the nine serotypes were antigenically distinguishable by LC-MS/MS and ELISA analysis