Viral Proteins
In addition to its RNA, the S and the N proteins are frequent targets for the detection of conorovirus. In contrast to that of the RNA, the development of a detection kit on viral proteins is still in progress. A probe, usually a specific antibody, is needed before a successful viral protein detection method can be developed. In early March 2020, Academia Sinica, Taiwan reported the first monoclonal antibody against N protein of Sars-CoV-2. With their antibody library in hand, the team screened against N proteins from 7 different viral species to obtain one antibody against only SARS-CoV-2 N protein, 9 against only SARS-CoV N protein, and 36 against both SARS-CoV-2 and SARS-CoV N proteins [10]. The results indicated that rapid immune-based test kit of SARS-CoV-2 coronavirus can be developed in the future. It also shows the complexity and time consuming to obtaining and screening an antibody for an unbiased test targeting specific viral protein. The procedure for the preparation of specific antibody from laboratory animal has been very well established and it could be expected that numerous antibodies specific for a SARS-CoV-2 protein will be reported soon. Twenty-five strains of antibodies from 3 COVID-19 patients have also been prepared from Chang Gung Memorial Hospital, Taiwan. There are 13 strains of monoclonal antibodies (mAbs) targeting on S protein, and 12 strains of mAbs targeting on N protein of the SARS-CoV-2. These antibodies especially those targeting on S protein can be a potential probe for the detection of S protein or the whole SARS-CoV-2 virus. The advantage of immune-based vial detection is its simplicity and speed (within 15 min). However, the antibodies prepared from SARS-CoV-2 protein antigen may cross-react with proteins from other similar viruses such as SARS-CoV and MERS, and thus a tedious screening procedure is needed before a specific testing kit can be developed.