As the Coronavirus spread, scientists began racing to understand the virus, its structure, method of infection, and effect on the human body. Dr. Kashtan and Dr. Chai stopped and asked a much more basic question: How does the virus survive the journey between an infected person and an uninfected person?
While the terms droplets and aerosols are now commonly tossed around, Dr. Kashtan and Dr. Chai are taking their questions to the lab – and applying the full force of their, knowledge, tools, and expertise to better understand how the virus is transmitted between people.
“Most virologist and epidemiologists are studying the virus itself – without asking how it remains viable as it is transmitted between people. This is a crucial question for flattening the curve and preventing infections in the first place.”
– Dr. Kashtan
Survival Rates in the Lab
In the initial study, which is currently in preprint, Dr. Kashtan compared the virus’s ability to survive in microdroplets composed of water, saliva, and SM buffer (a common laboratory medium) under typical indoor conditions. He discovered that the virus displayed much higher viability rates in dry saliva microdroplets than in the other two media. In other words, outside of the human body, saliva enables the virus to survive suspended in the air (especially in closed rooms) and survive on surfaces.
This study used a different, safer virus, Phi6, as a surrogate for the Coronavirus. (Phi6 infects bacteria, not humans, and is commonly used to study respiratory diseases). The two viruses are similar in size and structure, including having a lipid membrane and spike proteins.
What Is It About Saliva?
To answer this question, Dr. Kashtan joined forces with Dr. Chai. Together, they are now studying the physico-chemical properties of saliva that enable the virus to survive. Dr. Kashtan is contributing his knowledge of microbiology, while Dr. Chai brings her lab’s analytical methods to the table.
“We see value in conducting interdisciplinary research, with each of us contributing from our knowledge to combat this virus. We’re also taking a slightly different approach; rather than search for a cure, we’re asking how the virus survives in the environment – in order to reduce morbidity and mortality rates.”
– Dr. Liraz Chai
To start, they want to screen saliva samples from different people and assess virus survival rates between them (Dr. Kashtan). Then, in order to understand what characterizes saliva samples with high or low survival rates, Dr. Chai will analyze the saliva components: sugars, salts, proteins, and more. Once they’ve the combined their data, they will check for any correlation between composition and viral viability.
Next, they will take two approaches. First, top-down, they will begin eliminating components of saliva, while bottom-up they will start with water and begin adding components. In both cases, they will measure viral viability every step along the way, until identifying which factor(s) enable the virus to survive outside of the human body.
The next step will be devising a method to prevent the survival of the virus in saliva. Who knows? Perhaps the panacea will be a dispenser that automatically sprays the room – or a special chewing gum?