Unleashing Monoclonal Antibodies: Targeting Covid-19's Nucleocapsid Protein and Spike Antigens.

Since the end of 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected many people globally. Diagnosis and treatment of patients have a pivotal role in surviving them. Two units of virus namely, Nucleocapsid protein and Spike proteins play important roles in entering and affecting cells. These two substances can be good targets for producing monoclonal antibodies which can be useful in treatment, serological diagnosis tests, and even prevention by vaccination. In 2020, the nucleocapsid protein and spike proteins of SARS-CoV-2 were procured by the Razi Vaccine and Research Institute in Karaj. Subsequently, the proteins were injected into mice, with the injection dosage adjusted to ensure that the mice received an appropriate amount of the proteins. Subsequently, the spleen cells of the immunized mice were fused with myeloma cells. The most promising antibody-producing clones were selected for further evaluation. The immunoreactivity of the recombinant Np and S proteins was subsequently evaluated by implementing Western Blot and ELISA techniques. Finally, the most promising clones were cryopreserved using a nitrogen gas cryogenic method. The employment of an ELISA test resulted in the identification of eight clone antibodies, namely 3G1, 3G2, 3E7, H11, A11, F10, B11, and 2F6. These monoclonal antibodies were found to be against the S and Np antigens of SARS-CoV-2. Furthermore, the results of the western blot test indicated that each of these antibodies had antigenic sites against the Spike and Nucleocapsid protein independently, and the isotyping test revealed that they were from IgG (2a, 2b) or IgM class antibodies. The development of monoclonal antibodies has the potential to facilitate both diagnosis and treatment. The Nucleocapsid protein and Spike protein of SARS-CoV-2 show great promise in the creation of a new generation of monoclonal antibodies. Furthermore, a comprehensive approach to the early diagnosis of the disease can be facilitated by integrating the detection of these two proteins.