Recombinant Hypoallergenic Cat Allergy Vaccines.

Area of Science:

• Immunology
• Allergen-specific immunotherapy (AIT)
• Molecular vaccine development

Background:

• Cat allergy is a common condition, with Fel d 1, Fel d 4, and Fel d 7 identified as the primary allergens.
• Current allergen-specific immunotherapy (AIT) methods require improvement, necessitating the development of novel molecular forms.

Purpose of the Study:

• To develop and evaluate novel hypoallergenic recombinant fusion proteins (PreS-Cat 1-5) for cat allergy AIT.
• To assess the immunogenicity and efficacy of these PreS-Cat proteins in inducing IgE-blocking antibodies and modulating immune responses.

Main Methods:

• Epitope mapping of Fel d 4 and Fel d 7 allergens was performed using patient IgE binding inhibition assays.
• Five recombinant fusion proteins (PreS-Cat 1-5) were engineered, incorporating hypoallergenic peptides from major cat allergens (Fel d 1, Fel d 4, Fel d 7) fused to a hepatitis B virus (HBV) PreS carrier.
• Proteins were expressed in E. coli, purified, and characterized. Hypoallergenicity was confirmed via ImmunoCAP and basophil activation tests. Immunogenicity was assessed in rabbits, comparing antibody induction and IgE-blocking capacity against licensed AIT vaccines. T cell responses and cytokine induction (IL-10) were evaluated in peripheral blood mononuclear cell (PBMC) cultures.

Main Results:

• Recombinant hypoallergenic PreS-Cat 1-5 proteins were successfully produced and characterized.
• Two immunizations with PreS-Cat 1-5 in rabbits induced superior IgE-blocking antibodies against Fel d 4 and Fel d 7 compared to multiple doses of conventional AIT vaccines.
• PreS-Cat-specific antibodies effectively inhibited basophil activation. PreS-Cat 5 and PreS-Cat 1 induced significantly higher levels of IL-10, an anti-inflammatory cytokine, in PBMCs from allergic patients compared to native cat allergens.

Conclusions:

• PreS-Cat 5 and PreS-Cat 1 are highly promising molecular vaccine candidates for cat allergy AIT.
• These single-chain fusion proteins effectively combine key cat allergen peptides (Fel d 1, Fel d 4, Fel d 7) and demonstrate significant potential for improved immunotherapy outcomes.