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.