Nanoparticles: Efficient, safe and affordable platforms for developing vaccines against coronaviruses

ABSTRACT

Introduction: Vaccines need to be rationally designed to be delivered to the immune system for maximizing induction of dynamic immune responses. Virus-like nanoparticles (VLPs) are ideal platforms for such 3D vaccines. Coronaviruses have recently gained a lot of attention, due to the ongoing pandemic caused by SARS-CoV-2 and previous endemics by MERS-CoV. Methods: We have provided proof of concepts in murine models for effective development of VLP-based vaccines against MERS-CoV and SASR-CoV-2. We have used chemical conjugation or genetic fusion techniques to display receptor-binding domain or motif on our immunologically optimized (CuMVTT -VLPs). These VLPs incorporate a tetanus toxin epitope and ssRNA, TLR7/8 ligands. The vaccines were tested in murine models. Results: The vaccines are stable for more than a year at 4°C and highly scalable. Vaccination using subcutaneous or intranasal routes are feasible with nanoparticles. We demonstrated that these vaccines are highly immunogenic in mice as well as rabbits and can induce high avidity antibodies compared to convalescent human sera. Furthermore, the induced antibodies are cross-reactive with different VoCs (in case of SARS-CoV-2). The longevity of the induced immune response lasted longer than 120 days. Conclusion: Collectively, we show that VLP-based vaccines can efficiently induce high specific anti-RBD and spike antibodies that effectively neutralize different Coronaviruses and their VoCs. As Coronaviruses represent a continuous global threat to human health, it seems rational to further develop these vaccines.