The new ELISA serological test kit for diagnosing the SARS-CoV-2 infection was developed in collaboration with the National Institute for Infectious Disease Lazzaro Spallanzani in Rome, where the virus circulating in Italy was first isolated.
The antigen used in the solid phase of the kit is prepared, according to the patented protocol, in our BSL3 high biological containment laboratories. The native virus is first deactivated, to ensure complete safety.
Our kits detect the various serum antibody isotypes: IgA, IgG and IgM and other by-products of the immune response to the virus. In general, the detection of IgM - antibodies produced in the early post-infection phases - is a marker of the acute phase, while IgG are produced in a later phase. If a patient has been in contact with other Coronaviruses in the past, however, the IgG figures may rise more quickly than that of the IgM and IgA.
Detecting IgA is particularly important in SARS-CoV-2 infections, as these antibodies are produced in the respiratory mucus. The purpose of these antibodies is to bind to the virus and prevent its entry into the body, and are therefore an effective marker of the acute phase.
SARS-CoV - 2 is a “new” virus, and so requires the use of the native antigen. Using the “whole” virion allows us to determine antibodies directed against all viral proteins, even in their conformational state.
Molecular tests are most sensitive in the early stages of SARS-CoV-2 infection. The positivity rate, higher than 90% in the first three days of the onset of symptoms, declines quickly; less than 80% on the sixth day and well under 50% after 14 days.
The sensitivity of molecular tests is higher than serological tests if performed within 5.5 days of onset of symptoms, while the determination of IgM and IgA is more sensitive in later stages. In asymptomatic patients, performed alone the molecular method has a sensitivity of 52%, but determining IgM and IgA simultaneously sensitivity levels rise to more than 96%
|Performing serological tests and molecular tests contemporarily is particularly useful in the case of asymptomatic patients, allowing the immune responses against the virus to be highlighted, and thus estimation of the real incidence rate of the infection in the population.|
|Elaboration of data on the evolution of SARS-CoV-2 positives in relation to IgG IgM IGA antibody titer with PCR of molecular tests (see bibliography).|
Advantages of Enzywell SARS-CoV-2 kitsKits are based on the ELISA methodology. They are robust, well-known and accessible to all analysis laboratories.
They use the native antigen obtained from the actual virus circulating in the population.
protocol for all three kits:
|Same incubation time and temperature|
|Incubation at room temperature
(no thermostat required)
|Same dilution as the sample|
|Liquid and ready-to-use reagents|
|Interchangeable common reagents between kits|
IgA especially important in respiratory viruses, because they are produced in respiratory mucus, the entrance door of the virus;
IgG produced in the later stages of infection, a good marker of prior infection;
IgM, acute phase marker, the first antibody produced by the immune system in response to an infection.
Enzywell SARS-CoV-2 IgA|
Kit for determining anti-SARS-CoV-2 IgA in human serum
Sensitivity: 93.7% CI95%: 84.7 – 97.5
Specificity: 96.3% CI95%: 93.9 – 97.7
Enzywell SARS-CoV-2 IgG|
Kit for determining anti-SARS-CoV-2 IgG in human serum
Sensitivity: 92.5% CI95%: 83.6 – 96.8
Specificity: 95.8% CI95%: 93.4 – 97.3
Enzywell SARS-CoV-2 IgM|
Kit for determining anti-SARS-CoV-2 IgM in human serum
Sensitivity: 87.7% CI95%: 77.5 – 93.6
Specificity: 97.0% CI95%: 94.5 – 98.3
Zhang Wei et Al. Molecular and serological investigation of 2019-nCoV infected patients: implication of multiple shedding routes. Emerging Microbes & Infection. 2020; 9 (1). Ahead of printing.
Ng Lisa & Hiscox JA. Coronaviruses in animals and humans. The British Medical Journal 2020. Ahead of printing.
Guo L . et al. Profiling Early Humoral Response to Diagnose Novel Coronavirus Disease (COVID- 19). Clin Infect Dis. 2020, 21 mar. Ahead of printing
BèNè MC et Al. Good IgA bad IgG in SARS-CoV-2 infection? Clin Infect Dis. 2020, 11 Apr. Ahead of printing.
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Diesse Diagnostica Senese SpA is an Italian company with integrated and entirely in-house production of in vitro diagnostic systems. Its headquarters are in Siena. Since its foundation in 1980, the company has developed, produced and marketed innovative diagnostic systems primarily in the field of immunodiagnostics and automatic measurement of erythrocyte sedimentation rate (ESR). The company has a global presence in over 100 countries, three production sites and a research centre where the design and implementation of tests and new automated diagnostic detection tools meet Italian design and cutting-edge technology, making Diesse synonymous with "Diagnostics Evolution".