Dispatches from a pandemic: graduate students create COVID virus simulations

By Daniel Li

As it became clear in late February that COVID-19 was not going anywhere, four UC San Diego graduate students were planning their final project for the Numerical Analysis for Multiscale Biology course, which uses math to simulate biological processes.

The mechanical engineering and bioengineering students—Parker Dow, Cathleen Nguyen, Clara Posner, and Patrick Wall—decided to put their skills to a new use, and build a predictive model analysis that could bridge from the molecular biology of the SARS-CoV-2 virus to the epidemiology of the spread of infection through the population. The team started the three-week project in early March.

“A lot of times, when working on basic cell biology research, it can seem kind of removed from the bigger picture of what’s happening in the world,” Posner said. “But working on this coronavirus project is a lot more motivating since it can help with this current crisis that’s affecting us all.”

The idea to focus the project on COVID-19 was first brought up by Dow. According to Dow, he had started to see new scientific literature related to the novel coronavirus come out and it became increasingly apparent that some of the data could be used for computer modeling.

“I floated the idea to the group because I’d seen in a paper that they got a new structure of the coronavirus binding protein,” Dow said. “Our group started to do a bit more research on it and discovered that the scientific community had been publishing things daily, so we all wanted to take a stab at it.”

Each student focused on a different level of the project: cellular, molecular, and population scale. Wall created an alveolus in the lung with the MCell modeling tool to figure out the virus's rate of spread. Dow analyzed viral binding kinetics using BrownDye software. Posner used Virtual Cell (VCell) to create a transforming growth factor (TGF)-beta signaling induced lung fibrosis model. Nguyen focused on creating a population infection model using Vcell at the population level.

Two of the tools—Browndye and MCell—that the team used to model their systems were developed in-house at UC San Diego. Several local scientists, including UC San Diego Project Scientist Gary Huber and Salk Institute Staff Scientist Tom Bartol, were actively involved and helped guide them through the project. 

“The course instructors went above and beyond,” Wall said. “It was really helpful to reach out to them and ask for their expert knowledge. They also were instrumental in getting our models to run properly.”

This hands-on course is one of seven lab courses offered by the Interfaces Graduate Training Program in Multi-scale Biology that involves students from 11 graduate programs at UC San Diego and is directed by Professor Andrew McCulloch from the Department of Bioengineering.

 “The scientific challenges of addressing the COVID-19 pandemic are so daunting because they span from the scale of the spike protein on the virus, to the cellular and pathophysiological responses of the infected human to the population of the globe. Problems like these require the kinds of novel multi-scale approaches and interdisciplinary teamwork that the Interfaces program was designed to teach and encourage.

According to Wall, one of the challenges when they first started was that the data surrounding COVID-19 was sparse. To tackle this, the team looked at similar viruses, such as SARS, and used data from that to generate initial models. 

“The 2002 SARS virus was also a coronavirus outbreak. These viruses are so similar,” Wall said, “we were able to use a lot of the data that was generated in the mid 2000s to early 2010s on the SARS coronavirus and extrapolate our modeling based off of that.”

Nguyen added that because the coronavirus was evolving in real time, there were a lot of unknowns and the team was forced to make assumptions throughout the project. 

“Everyday you’re receiving new information about the pandemic and want to apply it to the models,” Nguyen said. “You make a lot of assumptions and those assumptions are changing based on new information. You're changing your inputs, your process, and with every simplification you make, you lose some accuracy in the models.”

Nguyen enjoyed how she was able to work together with students of different engineering backgrounds.

“I’m more of a mechanical engineering background, but the rest of my team members have more of a bioengineering background,” Nguyen said. “And the novelty comes when you’re trying to work on a multiscale project with people who have different expertise and skills.”