Considering the Value of Antiviral Resistance Testing in Certain Populations

At the ongoing ASM Microbe 2025, Meghan Starolis, PhD, senior science director of Infectious Diseases at the Quest Diagnostics’ Nichols Institute discussed her presentation, Conquering Antiviral Drug Resistance Via Novel Antivirals & New Testing Methods for Drug Resistance, which looked at genotypic and phenotypic testing and some of the benefits and challenges for each.

“With a genotypic method, it's a molecular based method, so you are detecting genetic determinants that confer antiviral resistance. Some of the pros of that approach are that it can be more automated and less labor intensive, but you can only detect genes that you know about. So there are certain genes that we know confer antiviral resistance, and those are the genes that we're able to detect. So there are unknown genes that could confer resistance, or unknown variants that we wouldn't be able to detect with those types of methods,” Starolis said. “On the other hand, there are phenotypic methods where you are growing the virus in a cell culture, and you are directly testing the effect of the compound. Because of this, you can detect resistance even when there's unknown genes or variants that might be causing the resistance. But growing virus in a cell culture can be can take a lot of time.”

One particular population, the immunocompromised, may benefit from antiviral resistance testing because of their treatment regimens, which may include antivirals for long periods of time, sometimes prophylactically, according to Stargolis.

"For our patients who are hematopoietic stem cell recipients, they might be taking prophylaxis for herpes simplex virus, and being exposed to those drugs can result in antiviral resistance over time," Starolis said. "So we're very concerned about antiviral resistance in this particular patient population, and for our immunocompromised patients, these viral diseases can present atypically, and ultimately they can have serious consequences, like delays in chemotherapy if they need that, or things like transplantation,” Starolis said.

One of the difficulties of testing is having access to them, and Starolis believes there are some strategies to overcome these challenges.

“For a lot of antiviral resistance testing, we're heavily reliant on lab developed tests that may be offered at reference laboratories or at academic health systems,” she said. “So I think that having access to FDA approved tests focusing on development of tests that could be adopted in more types of laboratories to have a more rapid turnaround time and have testing closer to the patient would really benefit that patient population.”