D2.197 - Dose-Dependent Immunogenicity and Toxicity of Polypeptide-Conjugated Hepatitis B Core Antigen Virus‐Like-Particle (HBcAg-VLP) Vaccine for Treatment of Shellfish Allergy

Allergen-specific immunotherapy (AIT) remains the only cure for shellfish allergy. Oral immunotherapy (OIT) achieves high rates of desensitization, yet it faces challenges with sustained efficacy, treatment compliance and toxicities. To address the urgent need for next-generation AIT, this study develops a nanoparticle-based recombinant protein vaccine against shellfish allergy. The objectives are (1) to evaluate the immunogenicity of virus-like particles (VLPs) conjugated with polypeptides derived from the major shellfish allergen, tropomyosin (TM), and (2) to assess the associated in vivo toxicity profile.

The vaccine was constructed via a plug-and-display platform, where a polypeptide derived from shrimp TM, Metapenaeus ensis 1 (Met e 1) allergen, was displayed on the surface of hepatitis B virus core antigen (HBcAg) VLPs using SpyTag/SpyCatcher technology. Five-week-old naïve female BALB/c mice were subcutaneously administered 2, 10, 30, 60, or 100 µg of the vaccine adjuvanted with AddaVax, following a prime-boost-boost regimen on day 0, 14 and 31. The mice were monitored until day 90, with sera collected at specific timepoints for analysis.

On day 45 (14 days after the third immunization), all tested doses elicited a significant (p<0.05) 19- to 29-fold increase in Met e 1-specific IgG antibody than VLP control, and sustained until D90. The induction of sIgG by10µg dose was similar to that by 30, 60, and 100µg doses (p=0.3344). As for Met e 1-specific IgG2a, 10µg dose elicited the highest level and was significantly higher than 2µg dose (p<0.05; 6-fold increase) and VLP control (p<0.05; 16-fold increase). A decreasing sIgG2a trend (p=0.1348) was observed above 10µg dose, suggesting 10µg to be the optimal dose to induce maximal Th1 response. Dose-dependent toxicity was not observed in major organs including liver, kidney and heart, validating the vaccine’s safety profile.

Ten micrograms of polypeptide-conjugated HBcAg-VLP vaccine is the optimal dose to elicit high Th1-prone immunogenicity with robust safety profile. These results have paved the way for testing vaccine efficacy against shellfish allergy in humans. (funded by General Research Fund [1413425], National Natural Science Foundation of China, Young Scientistst Fund [8250060998], Research Committee Postdoctoral Fellowship Scheme [PDFS2024/0716/24jh] and Direct Grants [4054775 and 4054881], CUHK)