AUTHOR=Tran Thi Nhu Mai , May Bruce Pearson , Ung Trong Thuan , Nguyen Mai Khoi , Nguyen Thi Thuy Trang , Dinh Van Long , Doan Chinh Chung , Tran The Vinh , Khong Hiep , Nguyen Thi Thanh Truc , Hua Hoang Quoc Huy , Nguyen Viet Anh , Ha Tan Phat , Phan Dang Luu , Nguyen Truong An , Bui Thi Ngoc , Tu Tieu My , Nguyen Thi Theo , Le Thi Thuy Hang , Dong Thi Lan , Huynh Trong Hieu , Ho Phien Huong , Le Nguyen Thanh Thao , Truong Cong Thao , Pham Hoang Phi , Luong Cong Y. , Y Nie Lim , Cao Minh Ngoc , Nguyen Duy Khanh , Le Thi Thanh , Vuong Duc Cuong , Nguyen Le Khanh Hang , Do Minh Si TITLE=Preclinical Immune Response and Safety Evaluation of the Protein Subunit Vaccine Nanocovax for COVID-19 JOURNAL=Frontiers in Immunology VOLUME=Volume 12 - 2021 YEAR=2021 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.766112 DOI=10.3389/fimmu.2021.766112 ISSN=1664-3224 ABSTRACT=The Coronavirus disease-2019 (COVID-19) pandemic caused by the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), has become a dire global health concern. The development of vaccines with high immunogenicity and safety is crucial for control of the global COVID-19 pandemic and prevention of further illness and fatalities. Here, we report development of SARS-CoV-2 vaccine candidate, Nanocovax, based on recombinant protein production of the extracellular (soluble) portion of the S protein of SARS-CoV-2. The results showed that Nanocovax induced high levels of S protein-specific IgG, as well neutralizing antibody in three animal models including Balb/C mice, syrian hamsters, and non-human primate (Macaca leonina). In addition, the viral challenge study using the hamster model showed that Nanocovax protected the upper respiratory tract from SARS-CoV-2 infection. No adverse effects were induced by Nanocovax in mice (Mus musculus val. Albino), and Rats (Rattus norvegicus). These pre-clinical results indicated that Nanocovax is safe and effective.