Progress and hurdles in the development of influenza virus-like particle vaccines for veterinary use.

Virus-like particles (VLPs), which resemble infectious virus particles in structure and morphology, have been proposed to provide a new generation of vaccine candidates against various viral infections. As effective immunogens, characterized by high immunogenicity and safety, VLPs have been employed in the development of human influenza vaccines. Recently, several influenza VLP vaccines have been developed for veterinary use and successfully evaluated in swine, canine, duck, and chicken models. These VLP vaccine candidates induced protective immune responses and enabled serological differentiation between vaccinated and infected animals in conjunction with a diagnostic test. Here, we review the current progress of influenza VLP development as a next-generation vaccine technology in the veterinary field and discuss the challenges and future direction of this technology.