Can Chromatography Improve SARS-CoV-2 Diagnosis?

2020 will be remembered as the year of Covid-19. No other disease in recent memory has had such an impact on society. Lockdowns, furloughs, home-working and tough rules around contact with family and friends have meant that the year will not be forgotten in a hurry. Researchers and regulators are striving to find ways to combat the pandemic to allow society to move forward allowing the economy and society to begin a move towards a ‘new normality’.

Vaccines and testing are now recognised as the two key requirements to allow that to happen. The vaccine rollout is starting to gather speed, but scientists are still trying to develop new and improved methods of testing for both the virus and the disease. A recent paper in the Croatian Journal of Infection reports on a study that assessed a serum-based test for Covid-19 using chromatography. Could it help us to return to normality?

A testing time for all

The diagnosis of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is based on the detection of viral RNA from swab samples using reverse-transcriptase polymerase chain reaction (RT-PCR). But researchers suggest that serology – the detection of antibodies in blood serum – is the best way to determine the spread of the disease in the general population. And knowing how many people have the virus and disease and the rate that they are spreading are key to how governments and health authorities react to safeguard vulnerable people and the general population.

Immunoassays could be used as an additional method to help give information regarding current or recent SARS-Cov-2 infection. The method could provide data for patients with exposure history and clinical symptoms that suggest Covid-19 but without a positive diagnosis. This can happen when diagnosis using RT-PCR fail and give either false-positive or false negative results. There are several factors why this can happen including time from infection, incorrect protocol, and cross-contamination.

Chromatography analyses antibodies

The researchers behind the work referenced above, analysed samples from Covid-19 confirmed patients and a control group with a negative SARS-Cov-2 test. The samples were tested for SARS-CoV-2 IgG and IgM and Covid-19 IgA antibodies using six different commercial serology tests including lateral flow chromatographic immunoassays. The analysis of virus samples using chromatography is discussed in the article, Ultrahigh Sensitivity Analysis of Adeno-associated Virus (AAV) Capsid Proteins by Sodium Dodecyl Sulphate Capillary Gel Electrophoresis.

The researchers found that ELISA (enzyme immunoassays) were slightly more sensitive than the immunochromatographic tests for IgM/IgA for patients with Covid-19. The IgG sensitivity was similar for both ELISA and the chromatographic methods. The authors caution though that the study has some limitations. They state that investigation on large number COV-ID-19 patients as well as asymptomatic persons should be performed to determine the sensitivity and specificity of serology tests in SARS-CoV-2 diagnostics.