John Lednicky’s phone is working overtime lately. Ever since a new human coronavirus burst onto the global stage last December, renowned virologists have sought Lednicky’s expertise. Even airline personnel have called, seeking guidelines for how to decontaminate their planes.
Lednicky, a research professor, is a microbiologist and molecular biologist in UF’s College of Public Health and Health Professions and the Emerging Pathogens Institute where he studies an array of disease-causing microorganisms. He has spent decades investigating coronaviruses that affect people, bats, birds, cats, cows, dogs, ferrets, mice and even pigs. But some of this work was proprietary for clients ranging from animal shelters to the swine industry to the U.S. government, and only a fraction of it is published in journals.
His lab offers something unique: expertise in aerovirology, or the science of studying viruses in the air we breathe. The new virus sweeping the globe, SARS-CoV-2, is thought to have originated in bats before spilling over into people, possibly via an intermediary mammal, where it causes a disease called COVID-19. Although scientists are still studying how SARS-CoV-2 spreads, many suspect one way is by airborne routes; and as luck would have it, Lednicky happens to excel at aerovirology. But to do this work properly, he points out, researchers must be able to not only detect viruses from air samples, which he calls “easy,” but also then recover and grow them in cell cultures, a process known as isolation, which poses many challenges.
“What a lot of people don’t know how to do is isolate the virus out of air samples,” Lednicky says. “That is something my lab specializes in. You have to be able to know if there is a risk or not from what is in the air.”
It is simple to pull bacteria and fungi out of the air, Lednicky says, their relatively large size makes them easier to collect. But pulling viruses from the air is more technically challenging; because they are so small, their physical properties make it difficult to collect and have them remain viable while using common air samplers. The air we breathe is full of viruses — not only human viruses but also those that infect bacteria, fungi, plants, animals and other organisms — and only some are capable of making people sick. And most of this small subset of viruses that potentially can harm humans are inactive due to becoming dried out or zapped by exposure to ultraviolet light — inactive viruses pose no health risk.
Lednicky worked with engineers at UF to improve air sampling equipment so that viruses, teeny tiny bits of matter measured in microns and nanometers, could be efficiently and effectively collected intact. There are only two air samplers in existence like theirs, and they cost around $60,000 each to build. Other air samplers are much less effective at collecting viruses from air, he says, and many inactivate viruses during the collection process. This makes it difficult to know whether or not certain viruses use airborne transmission routes to actively infect other hosts.
A few years ago, Lednicky worked with Chang-Yu Wu, a professor in UF’s department of environmental engineering services, and graduate students Maohua Pan and Tania Bonny, on a pilot study at UF’s student health center where they sampled air using their specialized equipment, dubbed the viable virus aerosol sampler (VIVAS). They found ten different viable human viruses — two of which were coronavirus species that cause common colds, known as 229E and NL63. They also found adenoviruses and influenza H1N1, H3N2, and B-Victoria viruses.
Bonny and Lednicky also teamed up on a separate study which determined that the human coronavirus 229E can stay active on surfaces, even when they are cleaned daily, for up to seven days. This revealed how stable and hardy some coronaviruses are in the environment.
“As long as the weather is relatively cool and it’s not very humid, this coronavirus will stay viable on environmental surfaces for a long time,” Lednicky says. This study is currently cited in the Canadian Pathogen Safety Data Sheet on SARS coronavirus. The Canadian PSDS publications are considered by most biosafety experts as the world standard for technical guidance concerning how human pathogens should be handled in lab settings.
One of his coronavirus studies that may be most relevant to clinicians showed that human coronavirus NL63 could infect kidney cells despite being known as a respiratory virus. Kidney cells from a donor had been cryopreserved by a commercial supplier and were later discovered to be infected. At the time, he and his team were unable to determine if infection happened prior to preservation, or if an ill laboratory worker at the supplier had infected the cells as they were being prepared for cryopreservation. Still, the results were pivotal because researchers had been unaware that NL63 even had the capacity to infect kidney cells. Later, scientists discovered that this same virus has the ability to cause diarrhea in people, which Lednicky says shows that it moves into other tissues.
“It has to get from the lungs to the intestinal tract somehow, and we think it goes systemic through the bloodstream,” Lednicky says. “This is important because the virus in this study gets into cells the same way that this new coronavirus, SARS-CoV-2, does.”
Following up on the idea of systemic infection, his lab became the first to document coronaviruses in human blood. During a study looking for arboviruses (these are spread by insect vectors such as mosquitoes or ticks) in Haitian children, his team found human coronavirus NL63 in the blood of four study participants. Next, they later found 229E in the plasma of a child. EPI Director J. Glenn Morris, M.D., collaborated on both of these studies. Both coronaviruses NL63 and 229E are causative agents of common colds, and are easily confirmed via nasal or throat swabs which are then subjected to molecular tests. But Lednicky and Morris identified and isolated them from plasma, which had never before been reported.
Air and blood are not the only substances from which Lednicky’s lab has pulled viruses. Working with Bonny, Morris and others in 2017, his research team also obtained evidence of an alphacoronavirus type in the feces of Brazilian free-tailed bats living year-round in Florida.
Lednicky’s past research into coronaviruses is wide-ranging, but he’s nowhere near done. He hopes to become involved in projects studying aspects of the new SARS-CoV-2 virus, such as how it is transmitted between people, using animal models to learn how it causes disease, its susceptibility to antiviral therapies, lipidomics and structure-function relationships related to its proteins and genes.
EPI Explainer: how many kinds of coronaviruses are there?
Coronaviruses are divided into four major groups: alpha coronaviruses, beta coronaviruses, delta coronaviruses and gamma coronaviruses. Human coronavirus strains 229E and NL63 are in the alpha group. Human coronavirus OC43, the new SARS CoV-2, and the viruses that cause severe acute respiratory syndrome (SARS) and Middle Eastern respiratory syndrome (MERS), all belong to the beta group. The delta group contains viruses that affect birds and pigs, and the gamma group contains viruses that affect birds and beluga whales. For more on the types that affect people, visit the CDC.
Written by: DeLene Beeland