August 4, 2022 | The U.S., the National Institute of Standards and Technology (NIST) has produced a reference material for use as a positive control when developing monkeypox diagnostic tests. The reference material marks the success of a proof-of-concept test, Scott Jackson, microbial geneticist at NIST told Diagnostics World News, and marks a shift in thinking at NIST since the COVID-19 pandemic.
NIST is not a public health agency, Jackson explained, and has traditionally not been involved in outbreak response. But in June 2020 scientists everywhere were looking for ways to help the COVID-19 pandemic.
Jackson’s team in NIST’s Complex Microbial Systems group was creating human fecal reference material—a reference material for the human gut microbiome—and they began testing how SARS-CoV-2 could be detectable in human waste as part of wastewater surveillance. Meanwhile, Peter M. Vallone’s Applied Genetics group at NIST developed positive control materials for SARS-CoV-2 diagnostic test development.
All of the SARS-CoV-2 standards prompted some new thinking, Jackson explained, about NIST’s role in outbreak response.
“It did sort of open this [question]: can NIST play this role, and more importantly can we do it rapidly? When an outbreak like this happens, you have to nip it in the bud if you want to have any real impact on controlling it.”
Jackson has been with NIST since 2014, but before that was at the Food and Drug Administration actively responding to food-borne illness outbreaks. He knows the importance of quick responses and accurate scientific materials for any outbreak. So he and his team set a goal of developing a reference material in 30 days—significantly faster than NIST’s typical reference material pipeline of three to five years. “If we can’t do it in 30 days, then it’s rather futile and it’s not fast enough,” he said.
As soon as news came of a U.S. case of monkeypox, Jackson wondered if this was the right proof-of-concept for the idea. When it became clear that cases were spreading, NIST reached out to the Centers for Disease Control and Prevention to connect with the monkeypox response team and pitch the plan. “They were at our side the whole time. We could bounce ideas off of them; we could troubleshoot,” Jackson said.
And the NIST team was successful. “It sort of established a precedent that NIST can play a role in rapid response to outbreaks,” he said.
Though the monkeypox reference materials are the first created under this tight timeline in response to a public outbreak, this is not the first DNA reference material NIST has produced.
“We’ve done this over the last nine years several other times,” Jackson said. “We’ve developed some pathogen standards with the FDA; we’ve worked with the EPA to develop some environmental surveillance DNA standards. When it came to putting DNA in a tube and putting a certified value on it, we were really good at that already—which is the only reason we could tell ourselves maybe we could pull this off in 30 days!”
The search for reference material started with modeling the monkeypox genome in silico, working closely with CDC. “Obviously we didn’t want to clone the whole monekypox genome because that would first be dangerous and second be unnecessary,” Jackson said. Instead, the team began with targeted genomic sequences previously identified by CDC, the US Army, and others as diagnostically useful.
When the DNA targets were decided upon—9 targets about 100 base pairs each—NIST submitted them for DNA synthesis to two companies: Twist Bioscience and IDT, Integrated DNA Technologies.
“Because we were in a rush and we wanted to be sure it came through, we sent our design to two companies. We said whichever one gets it to us first, we’ll use that material,” Jackson says. “They came in within a day of each other and they were both correct,” Jackson says, declining to give more detail.
From there, NIST expanded the clone, aliquoted it into 1,000 units, and performed characterization and certification testing on the material, ensuring that every unit of reference material is homogenous, stable, and contains the same concentration of plasmid.
Each microliter contains 110,000 copies of the plasmid DNA, plus or minus 10%. The research-grade test material is freely available for use by test manufacturers and testing laboratories who can use it as a positive control for their test development.
Jackson is hopeful that the research test materials will have important impacts on the trajectory of the monkeypox outbreak in the U.S. “Unfortunately, we don’t have a parallel universe where we can do the control experiment, but it’ll be interesting for me to see how our material impacts this outbreak and its expansion within the community,” Jackson says. “The question is, ‘Is there some measurable impact that our material will have on this outbreak response?’”
He certainly believes so. In 2021, NIST launched a program to develop standards around pathogen surveillance in wastewater. “In my opinion, the thing that’s going to prevent this from happening again is wastewater surveillance,” Jackson said. “That’s going to be the early indicator alarm that tells us somethings happening in [certain] communities.” And wastewater surveillance requires reliable reference materials to test against.
In his correspondence with CDC epidemiologists since the monkeypox reference materials were released, he’s learned about many more pathogens under surveillance that could possibly benefit from NIST’s material generation. “They basically gave us a shopping list!” he laughed.
“That’s flattering and it’s great, but it brings up bigger questions about how this is funded, how do we coordinate with other federal agencies. This was a fire drill—an experiment almost. Now we’ve convinced ourselves that we can do it, the question is are we going to do it sustainably and what does that look like.”