A Multivalent and Thermostable Nanobody Neutralizing SARS-CoV-2 Omicron (B.1.1.529).

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants have risen to dominance, which contains far more mutations in the spike protein in comparison to previously reported variants, compromising the efficacy of most existing vaccines or therapeutic monoclonal antibodies. Nanobody screened from high-throughput naïve libraries is a potential candidate for developing preventive and therapeutic antibodies. Methods: Four nanobodies specific to the SARS-CoV-2 wild-type receptor-binding domain (RBD) were screened from a naïve phage display library. Their affinity and neutralizing activity were evaluated by surface plasmon resonance assays, surrogate virus neutralization tests, and pseudovirus neutralization assays. Preliminary identification of the binding epitopes of nanobodies by peptide-based ELISA and competition assay. Then four multivalent nanobodies were engineered by attaching the monovalent nanobodies to an antibody-binding nanoplatform constructed based on the lumazine synthase protein cage nanoparticles isolated from the Aquifex aeolicus (AaLS). Finally, the differences in potency between the monovalent and multivalent nanobodies were compared using the same methods. Results: Three of the four specific nanobodies could maintain substantial inhibitory activity against the Omicron (B.1.1.529), of them, B-B2 had the best neutralizing activity against the Omicron (B.1.1.529) pseudovirus (IC50 = 1.658 µg/mL). The antiviral ability of multivalent nanobody LS-B-B2 was improved in the Omicron (B.1.1.529) pseudovirus assays (IC50 = 0.653 µg/mL). The results of peptide-based ELISA indicated that LS-B-B2 might react with the linear epitopes in the SARS-CoV-2 RBD conserved regions, which would clarify the mechanisms for the maintenance of potent neutralization of Omicron (B.1.1.529) preliminary. Conclusion: Our study indicated that the AaLS could be used as an antibody-binding nanoplatform to present nanobodies on its surface and improve the potency of nanobodies. The multivalent nanobody LS-B-B2 may serve as a potential agent for the neutralization of SARS-CoV-2 variants.

Grand Challenges in Bio-Nanotechnology to Manage the COVID-19 Pandemic

The outbreak of the COVID-19, a human beta coronavirus severe acute respiratory syndrome (SARS-CoV-2) virus infection, has severely affected the world. The pandemic is not yet in full control due to a lack of rapid diagnostics and therapeutics. This viral infection continues to result in a steadily increasing loss of life, and it has also emerged as a significant global socio-economic burden. As result, it has united many countries for the purposes of exploring molecular biology, biomedical science, and the nanotechnology to manage COVID-19 successfully. As of today, the current priority is to investigate novel therapies of high efficacy and smart diagnostics tools for early-stage disease diagnostics along with monitoring. Keeping these advancement and challenges in mind, this perspective article mainly highlights the contribution and possibilities of bio-nanotechnology to manage the COVID-19 pandemic, even in a personalized manner. Authors also pinpoint barriers to the utilization of current bio-nanotechnology to facilitate a more accurate understanding of COVID-19 and to lead the way toward personalized health and wellness. Furthermore, we follow the discussion of the features and challenges in upcoming bio-nanotechnology approaches for COVID-19 management. In this progressive option report, bio-nanotechnologies that have been enriched with the power of artificial intelligence and optimized at the personalized level have been found to lead to a sustainable treatment and cure strategy at a global population scale. Copyright © 2020 Paliwal, Sargolzaei, Bhardwaj, Bhardwaj, Dixit and Kaushik.