Scientists develop cross-species coronavirus test

In a breakthrough that will help scientists track coronavirus variants in wild and domestic animals, researchers report that they can now detect exposure to the SARS-CoV-2 virus in any animal species. Most coronavirus antibody tests require specialized chemicals reagents to detect host antibody responses against the virus in each species tested, hampering research in all species.

The virus that causes COVID-19 in humans also infects a variety of animals, said Ying Fang, a University of Illinois Urbana-Champaign professor of pathobiology and virologist, who led the new research. So far, the virus has been detected in cats, dogs, rodents, deer, monkeys and a variety of farm and zoo animals. The virus also mutates in these hosts, potentially leading to new variants that can endanger their health – and that of humans.

“Highly sensitive and specific diagnostic reagents and tests are urgently needed for rapid detection and implementation of infection prevention and control strategies in animals,wrote the researchers in the journal mspherewhere their findings are reported.

The new coronavirus test focuses on antibodies directed against a protein, called protein N, which is embedded in the virus’s nucleocapsid – a structure made up of proteins and nucleic acids contained in a viral membrane. The N protein is a better target than viral membrane-bound proteins that are typically used in testing for antibody responses, Fang said.

The N protein is more abundant and better conserved than the proteins used in most tests.”

Ying Fang, University of Illinois Urbana-Champaign Professor of Pathobiology and virologist

This means the structure of the protein is more consistent across species, making it a good target for antibody testing of all species.

The team used an N-protein blocking ELISA protocol for their test. This method involves coating an ELISA plate with protein N, then adding a serum sample from any animal being tested. If the animal has been infected with the coronavirus, its serum will contain anti-N-protein antibodies, which will bind to the N-protein coated plaque. Scientists then wash the plate and add a biotin-labeled secondary monoclonal antibody that targets protein N. If the animal tests positive for coronavirus infection, its antibodies will block secondary antibodies from binding to protein N. If the animal has not been infected, the monoclonal antibodies attach to the coated plate and generate a color signal when specific chemicals are added to the plate.

The researchers validated their test using samples from a variety of animals with known SARS-CoV-2 infection status, finding the tests had a sensitivity of over 97% and a specificity of 98 %. Further tests on domestic cats showed the test was able to detect infection within seven days of exposure to the virus.

Developing accurate cross-species coronavirus tests provides a useful tool for field surveillance of SARS-CoV-2 in animal populations, helping scientists identify potential new animal reservoirs to prevent future outbreaks, Fang said. .

The National Institutes of Health supported this research.