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Background: Cat allergy in human subjects is usually caused by the major cat allergen Fel d 1 and is found in approximately 10% of the Western population. Currently, there is no efficient and safe therapy for cat allergy available. Allergic patients usually try to avoid cats or treat their allergy symptoms., Objective: We developed a new strategy to treat Fel d 1-induced allergy in human subjects by immunizing cats against their own major allergen, Fel d 1., Methods: A conjugate vaccine consisting of recombinant Fel d 1 and a virus-like particle derived from the cucumber mosaic virus containing the tetanus toxin-derived universal T-cell epitope tt830-843 (CuMV TT ) was used to immunize cats. A first tolerability and immunogenicity study, including a boost injection, was conducted by using the Fel-CuMV TT vaccine alone or in combination with an adjuvant., Results: The vaccine was well tolerated and had no overt toxic effect. All cats induced a strong and sustained specific IgG antibody response. The induced anti-Fel d 1 antibodies were of high affinity and exhibited a strong neutralization ability tested both in vitro and in vivo. A reduction in the endogenous allergen level and a reduced allergenicity of tear samples, were observed., Conclusion: Vaccination of cats with Fel-CuMV TT induces neutralizing antibodies and might result in reduced symptoms of allergic cat owners. Both human subjects and animals could profit from this treatment because allergic cat owners would reduce their risk of developing chronic diseases, such as asthma, and become more tolerant of their cats, which therefore could stay in the households and not need to be relinquished to animal shelters., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: In mice, highly repetitive antigens, such as those present on bacterial or viral surfaces, efficiently cross-link B-cell receptors and therefore induce strong IgG responses. In this study we covalently coupled a synthetic 16-amino-acid sequence of the allergen Der p 1 to a virus-like particle derived from the bacteriophage Qbeta (Qbeta-Der p 1)., Objective: We evaluated the safety and immunogenicity of Qbeta-Der p 1 in human subjects and compared different doses and routes of immunization., Methods: In a phase I trial 24 healthy volunteers were randomly assigned to one of 4 treatment groups. Group 1 received 50 microg of Qbeta-Der p 1 intramuscularly, group 2 received 50 microg of Qbeta-Der p 1 subcutaneously, group 3 received 10 microg of Qbeta-Der p 1 intramuscularly, and group 4 received 10 microg of Qbeta-Der p 1 subcutaneously. Boosting immunizations with 10 microg were given after 1 and 3 months. Antibody titers were measured after 1, 3, 4, 6, 12, and 18 months., Results: The vaccine Qbeta-Der p 1 was well tolerated. Significant IgG responses were observed 4 weeks after a single injection. Individuals receiving 50 microg of the vaccine had significantly higher IgG titers than those vaccinated with 10 microg. However, the route of immunization (subcutaneous vs intramuscular) had no effect. In the 50-microg dose group, strong antibody responses against Der p 1 with average titers of 1:2000 were obtained., Conclusion: Vaccination with a peptide antigen covalently coupled to highly repetitive virus-like particles represents an adjuvant-free means of rapidly inducing high antibody titers in human subjects., Clinical Implications: Allergens coupled to virus-like particles can be used to enhance the efficiency of allergen-specific immunotherapy.