Medical school researchers imagine COVID-19 infection in mice
Scientists at the medical school used the microscopic technology to image the COVID-19 infection in mice, which will hopefully help develop treatments.
Beatriz Horta
Journalist
Yale News
In a recent study, scientists at the Yale School of Medicine used imaging techniques to visualize how the coronavirus was infected in mice.
The next frontier scientists must overcome in the pandemic, according to Pradeep Uchil, a medical school researcher, is finding an effective treatment for SARS-CoV-2. He explained that while preventative measures such as vaccines are essential, they are not a substitute for treatment when a person becomes seriously ill from the virus. Working with other labs in the medical school, Uchil and other researchers used bioluminescent coronaviruses, edited to appear under a special microscope, to demonstrate what the virus does once it enters the body.
“We have been working with viruses in my lab for a long time with many different viruses from HIV to flaviviruses to SARS-CoV-2 now because of the pandemic,” associate professor of infectious diseases and microbial pathogenesis Priti said Kumar. “So most of these viruses don’t have a cure, and we all basically rely on immune responses and hope that we have a vaccine that we could use to effectively prevent infection with the virus.”
Uchil added that he had a personal motivation to do this study, as his father died from the Delta variant of COVID-19 in India and he felt there was nothing he could do to save it.
Walther Mothes, professor of microbial pathogenesis and lead author of the project, explained that the researchers aimed to elucidate what the immune system needs to fight the virus.
The type of antibody a vaccine develops is extremely important in determining its effectiveness, he said. Unfortunately, there’s no good way for scientists to figure out which antibody is essential in fighting the coronavirus, Kumar said. Viral infection is what she calls a “black box”.
“Often times, if the vaccine fails or doesn’t work, no one knows why,” Kumar explained.
The results showed that having neutralizing antibodies in the body, which signal the viral antigen, is extremely helpful but not enough to prevent cells from being infected. The cells could still be infected, as the video shows, if the antibodies were not present in high enough amounts.
Therefore, the researchers concluded that another type of immune cell, capable of finding infected cells and killing them, was still needed to “clear” the infection.
“Antibodies can only protect us if the immune system is able to find and kill the infected cells, defeating the virus,” Mothes said.
Another important finding from the study was that after entering the body through the nose, SARS-CoV-2 travels to the lungs, where it replicates and then returns to the nose. According to Kumar, this could help explain why individuals continue to infect other days after developing the disease and why many can be positive even after the infection window.
Imaging of the viral infection has enabled scientists to determine these findings and may also aid in the development of future COVID-19 treatments. One of the biggest breakthroughs in in vivo imaging – which takes place inside an organism as opposed to a controlled environment like a Petri dish – could bring is the rapid test of drugs.
During in vivo imaging, instead of having to euthanize the animal to analyze the viral infection and the effects of the drugs, scientists can keep the animal alive and follow the spread of the virus over several days, according to Ullah.
“It helps us see the effect of a drug within the time limits of the infection,” Ullah explained. “In a matter of days, we can determine whether or not the drug will work in humans.”
According to Kumar, the lab’s experience with imaging other viruses such as HIV, Zika, and West Nile virus in vivo prepared them to deal with SARS-CoV-2 during the pandemic.
Research with infectious viruses such as the coronavirus requires a Level 3 biosafety lab, which Kumar and Mothes had previously founded at Yale for their work on HIV.
BSL-3 labs prevent both scientists and others from coming into contact with the live virus by having negative air pressure and preventing the virus from leaving the lab using special personal protective equipment practices.
According to Center for Disease Control, a person can remain contagious for about 10 days after the first symptoms of COVID-19 appear.
