Bio-Shield 2019-nCoV Total ImmunoglobulinsBio-Shield 2019-nCoV Total Immunoglobulins (Ig) is a semi-quantitative ELISA test for the determina-tion of IgA, IgM and IgG against the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) in human serum or plasma specimens.
Coronaviruses are enveloped, positive-sense and single-stranded RNA viruses with a nucleocapsid of helical symmetry and are composed of several proteins including the Spike (S), Envelope (E), Membrane (M) and Nucleocapsid (N) proteins. The S protein is very immunogenic with the Receptor Binding Domain (RBD) being the target of many neutralizing antibodies1.
The 2019 SARS-CoV-2 emerged in the Chinese province of Hubei (Wuhan) in December 2019 and has been declared a pandemic on 11 March 2020. This outbreak has spread rapidly, with millions of reported cases and thousands of deaths worldwide. Currently, there is no medication or vaccine available against infection with this new virus.
Antibodies are produced by the immune system after an average of 7 days after infection. The Immunoglobulins M and A and G are produced in response of the infection and the Seroconversion for IgG and IgM occurs simultaneously or sequentially*. Both IgG and IgM titers reach a plateau within 6 days after seroconversion. Within 19 days after symptom onset, all patients tested are positive for IgG against SARS-CoV-2*. Serological testing may be helpful for the diagnosis of suspected patients with negative RT–PCR results (determining the number of cases of COVID-19) and for the identification of asymptomatic infections.
* Long, Q., Liu, B., Deng, H. et al. Antibody responses to SARS-CoV-2 in patients with COVID-19. Nat Med (2020).