Current diagnostic tests for the SARS-CoV-2 coronavirus are based on RNA: looking for the presence of viral genes in a culture of cells from the nose or throat.
However, this evidence is limited in some countries, such as Spain. When we speak with Spanish health workers who fight COVID-19 in hospitals, they confirm that the coronavirus test, which takes 24 hours to obtain results, is currently only performed on those admitted to the Intensive Care Unit (ICU). There is no test available to everyone who would or should have it. This situation, added to the fact that there are many mild cases that could have been due to colds or even that were asymptomatic, makes us wonder: how many cases of COVID-19 have gone unnoticed?
To find this out, scientists would need to test a person’s blood for antibodies to the new virus. Such tests can also detect active infections, but more importantly: they can determine if a person has been infected in the past, because the body retains antibodies against pathogens that it has already overcome.
As journalist Gretchen Vogel publishes for Science magazine, laboratories and companies around the world are working hard to develop these types of antibody tests, and some have already been used in the laboratory and have received commercial approval. One of these tests has just been presented by virologists at Mount Sinai Hospital.
According to Science , this is one of the first detailed protocols of its kind to be widely distributed, and the procedure is simple enough that other labs can easily scale it – it could detect thousands of people a day and find out clues about immunity to COVID. -19.
To create the test, the researchers began by designing a slightly altered version of the “spike” protein in the outer layer of SARS-CoV-2. As we have previously explained in Very Interesting, this protein helps the virus to enter cells, and is a key target in the immune reaction against the virus, since the body produces antibodies that recognize the protein and tag the virus to proceed to its destruction. They also isolated the short fragment of the spike protein called the receptor-binding domain (called RBD), which the virus uses to bind itself to the cells it tries to invade. They then used cell lines to produce large amounts of the altered spike proteins and RBD.
Those lab-made molecules provided the basis for the test, which consists of the following: Antibodies in a blood or plasma sample change color when they recognize a target protein . At the moment, initial analyzes of four blood samples from three confirmed COVID-19 patients and 59 serum samples stored before the outbreak started showed that the test worked.
A promising future
SARS-CoV-2 antibody tests could help not only find out how quickly patients develop immunity; but also, in the future, to identify already recovered patients, who could then donate their blood to treat critically ill patients.
Additionally, antibody testing could also provide key data for efforts to mitigate the course of the pandemic. By indicating how much of the population is already immune due to mild infections, antibody data could offer the key to understanding how quickly the virus continues to spread.
More information:
SARS-CoV-2 diagnosis pipeline
