Test detects coronavirus infection in several animals – 7/6/2023 – Health

The coronavirus-like group of viruses, which includes Sars-CoV-2, which is responsible for the Covid pandemic, is known to infect different animals, including pigs, ferrets, bats, felines and humans.

Early detection of the presence of the pathogen in pets and farm animals is essential to prevent the occurrence of new outbreaks and possible mutations that may arise in these populations.

With that in mind, scientists from the University of Illinois and the College of Veterinary Medicine at Cornell University, in the United States, have created a diagnostic test capable of identifying a previous infection with Sars-CoV-2 or other coronaviruses of medical importance in several species, including dogs and cats.

The article describing the new test was published this Thursday (6) in the scientific journal mSphere, edited by the American Society for Microbiology.

The test developed is of the serological type and searches for anti-N protein antibodies (nucleocapsid), present in the nucleus of the coronavirus and which is less subject to mutations that the virus can undergo when replicating in the host organism, unlike membrane proteins, such as the protein Spike.

Serological tests seek to identify antibodies in the human body specific to the virus and are more effective when performed after the eighth day of infection. In the case of the N protein, anti-N antibodies are developed after an infection, both in humans and other animals, or induced by vaccination, in vaccinated people.

In the new kit, the researchers investigated the effectiveness and specificity of four monoclonal antibodies, which are molecules produced artificially from clones of a single cell and which help to neutralize the virus: mAb 41-10, 86-12, 109- 33 and 127-3.

Then, they tested each of the antibodies in vitro on cells containing viral particles from the original Wuhan strain and four variants of Sars-CoV-2; and also against other coronaviruses such as SARS, MERS and HCoV 229E, a common cold coronavirus.

After initial tests, the scientists observed that the 127-3 monoclonal antibody had a better sensitivity to different viruses, and it was selected to construct the diagnostic test. From blood samples, the test looks for anti-N protein antibodies, which bind to the monoclonal antibody in the test compound. If so, the connection takes place and a light signal appears. If not, there is no link—probably indicating that there has not been an infection in the past.

To determine the effectiveness of the test, the researchers inoculated cats with coronavirus in the laboratory. The result showed a sensitivity (when the antibody binds to the compound in the test) of 97.8% and a specificity (when the positive result is really positive, and not a false positive) of 98.9%, considered high for serological tests .

Next, the researchers tested dogs that were in a veterinary clinic with symptoms similar to coronavirus infection to investigate possible contact with the virus. Two animals tested positive, and the infection was confirmed with additional RT-PCR testing, reinforcing the high efficacy of the serological test. The owner of one of the two dogs had presented a positive diagnosis for Covid a month earlier, which reinforces the possibility that humans and other animals share the virus.

Despite being a test with good accuracy, the study has its limitations, such as having tested so far only companion animals (dogs and cats), not wild animals, such as weasels and ferrets.

On the other hand, the diagnostic test differs from others on the market because it also has good sensitivity to detect previous infection in other animals, helping to identify early symptoms compatible with the disease caused by the coronavirus in these species, even over a period of more than six months. since the initial infection.

The authors conclude that the monoclonal antibodies created are good target molecules for the detection, even if late, of viral infection in different animal hosts, and that they can be a good tool for the health surveillance of new virus reservoirs. “Basically, we have developed a diagnostic test that can be applied in all species to detect exposure to Sars-CoV-2 in animals”, adds Ying Fang, a professor at the University of Illinois and coordinator of the study.