Super Sleuthing to Save Citrus

UMD Professor Anne Simon and her startup Silvec Biologics work to unravel the unsolved mystery of a lethal plant disease

Anne Simon is on a mission to stop a silent killer—a relentless pathogen that wreaks havoc from the U.S. to Europe and beyond.

“There’s no cure, there’s no treatment, there’s nothing,” said Simon, a professor of cell biology and molecular genetics at the University of Maryland. “It has decimated Florida and moved into the central regions of California. It’s all over southern Texas, and it’s all over Africa and China and India. I mean it’s just terrible.”

Simon is talking about huanglongbing (HLB), more commonly known as citrus greening, a lethal disease that relentlessly attacks plants, and more specifically citrus trees. Without a cure, HLB could spell the end of the citrus industry.

“We’re running out of time for these trees,” Simon warned. “We may only have another eight to 10 years before most citrus trees are infected worldwide.”

How can this citrus killer be stopped? For years, the answer has been a mystery. But, as a researcher who spent years as a science advisor for the hit television series “The X-Files,” Simon knows a thing or two about solving mysteries.

Four years ago, in her lab at UMD, Simon took her first step toward a potentially effective citrus greening solution when she discovered a symptomless virus-like agent that can deliver disease-fighting weapons directly into citrus trees.

“What we can do is attach something we want to our virus-like agent, our independent mobile RNA as we like to call it,” explained Simon, who is recognized around the world for her work in plant virology. “Once the RNA is in the plant, the plant has an immune system called RNA silencing and can chop it into pieces, and those little pieces could be directed against pathogens.”

Simon’s patent-pending discovery of the virus-like agent was licensed by UMD in 2019 to the Gaithersburg, Maryland-based startup Silvec Biologics. Led by Simon’s brother, Rafael Simon, a former chief operating officer with extensive venture capital experience, and fueled by further discoveries in Simon’s UMD lab and university support, Silvec Biologics aims to bring pathogen-fighting products to market within the next few years.

“We started with just one little room at IBBR with just one person and we’ve quickly grown in a couple of years to a 6,000-square-foot facility in Gaithersburg,” Simon said. “We have lots of ideas in different stages of working and I’m hoping we can successfully develop a product that works and will give the citrus industry hope.”

The aha! moment

For Simon, whose research focuses on small viruses in plants, the aha! moment that started it all came in 2017 when she discovered a strange version of a virus that was like nothing she’d ever seen.

“It did something that no virus like it had ever done before,” Simon explained. “It was able to move through citrus by itself and it didn’t have any symptoms, meaning that it could possibly be used as what we call a virus vector, to deliver small RNA into these plants.”

Simon immediately realized that this strange viral agent could be what scientists had been looking for—a vehicle that could deliver pathogen-killing weapons into infected citrus trees.

“I called up the USDA and I said, ‘I may have a vector for citrus greening—do you have any money left over for the citrus greening program because I need to get to work on this immediately,’” Simon recalled. “And they gave me a half-million dollars, and I got some people working on it and that’s when we were able to make some real progress.”

A path to stability

Citrus greening is spread by tiny insects called psyllids that inject the disease-causing HLB bacteria into the leaves of the tree. To fight the disease, Simon worked to develop a small RNA engineered to fight the citrus greening pathogen, one that could be delivered directly into the plant. The next challenge was stability—making sure the disease-fighting RNA would be stable and could keep working for the life of the tree.

“We know that viruses can be a solution,” Simon said, “but when you put stuff into viruses it’s not stable, the virus eventually kicks it out. And no one understood why that happens it just does.”

After three years and plenty of trial and error in the lab, the stability problem was solved; the proof was in the plants.

“We have citrus plants now that have the virus vector in them with these small RNAs,” Simon said. “It’s been about a year and a half since the infection, and they’re doing great, there are zero symptoms.” Simon believes that this strategy of using a symptomless virus vector to deliver stable, pathogen-targeted RNAs could work for other at-risk crops as well.

“This vector can infect citrus and also grapevine and tobacco and lots of different plants,” Simon said. “We know that in our laboratory host we can completely eliminate infections by very pathogenic viruses, so we’re working on additional versions of this, and we hope to have a solution for grapevine and citrus and cacao in the future.”

From “highs and lows” to “we can do this”

It’s been a long road, but Simon is energized by the possibilities ahead.

“When you’re going through this process you have highs and lows—there’s nothing that says just keep trying you’ll get it,” Simon explained. “You have investors, you don’t want to be leading people on and you’re giving hope to the industry, and you don’t want to be leading them on. But it is all working so far and now I’m at the point where I’m saying we can do this.”

Away from the lab, Simon still occasionally consults on entertainment and government projects, and she continues to enjoy some celebrity status for her work on all nine seasons of “The X-Files,” the 2016 X-Files miniseries and her 2001 book “The Real Science Behind the X-Files: Microbes, Meteorites and Mutants.” She even appears as a regular guest at X-Files conventions.

“I’ll be at an X-Files convention as one of the people who signs autographs and stuff,” Simon explained. “The fun thing is having long lines of people who say they’ve always wanted to meet you.”

In all aspects of her life, Simon is as passionate as ever about her work as a scientist. She never imagined launching a startup like Silvec Biologics, but she’s more than ready to take on the challenges ahead, grateful for the support and partnership UMD has provided throughout this process and eager to apply her extensive knowledge and experience in ways where she can make a real difference, in the citrus industry and beyond.

“I’ve developed all of this knowledge for 40 years, so isn’t it time that I start to give back?” Simon reflected. “Using all of this knowledge is really beneficial for society, for the university and for the state. If we can come up with a solution for some of these problems and if we can then help others also come up with solutions, I will be beyond happy about that.”