UNIVERSITY PARK, Pa. — When a disease-causing virus jumps from one species to another, the infection often fizzles out. However, occasionally, it can take hold in the new host species, leading to a pandemic. Scientists are currently monitoring the H5N1 highly pathogenic avian influenza, known for causing bird flu and now found in cows and humans. The pressing question remains: can we predict when infections will naturally die out and when they will persist?
New research led by scientists at Penn State and the University of Minnesota Duluth has identified characteristics that might help forecast whether a pathogen will endure. Understanding the factors influencing viral spread shortly after it crosses into a new population could provide crucial insights for halting the spread of new diseases, according to the research team. The study was published on August 21 in the journal PLOS Biology.
Insights from the Study
“Pandemic prevention efforts largely focus on identifying the next pandemic pathogen, but that’s like finding a needle in the haystack,” said David Kennedy, associate professor of biology at Penn State and senior author of the paper. “This work helps us figure out which outbreaks to worry about so that we can direct our public health resources where they need to go to prevent and respond to disease emergence.”
While pandemics are rare, spillover events, where viruses move between different host species, occur frequently. The challenge lies in identifying which of these events warrant attention. Clara Shaw, the lead author of the study and now an assistant professor of biology at the University of Minnesota Duluth, explained the research’s aim: to determine if measurable characteristics of a spillover event could predict the virus’s persistence in a new population.
Methodology and Findings
The researchers utilized a worm model system to study viral spillover, allowing them to observe disease transmission and emergence at a population level. They examined eight strains of worms from seven species of the Caenorhabditis nematode, a model system sharing many genes with humans. The worms were exposed to the Orsay virus, a nematode virus, to induce a spillover event.
The team measured several traits of the worm populations, including infection prevalence, viral load, viral shedding, and susceptibility. Using mathematical models, they assessed each trait individually and collectively to determine their link to virus emergence as the worms were transferred to new environments.
“The dynamics of how the virus spreads during the few days after transmission are crucial for predicting long-term viral persistence,” the researchers noted.
Three factors—infection prevalence, viral shedding, and susceptibility—were positively correlated with a virus’s ability to establish itself in a new host population. Notably, infection prevalence and viral shedding accounted for more than half of the differences observed in virus persistence.
Implications for Future Research
The study’s findings suggest that early traits can provide significant insights into a virus’s future trajectory. However, the researchers found that infection intensity did not predict virus persistence.
Looking ahead, the team plans to explore how pathogens adapt to new hosts, focusing on the genetic changes that enable persistence. “Understanding the genetic changes that occur when a pathogen adapts to a new host is crucial,” Kennedy said.
This research was supported by funding from the U.S. National Science Foundation. At Penn State, researchers are tackling real-world problems impacting health, safety, and quality of life globally.
Broader Context and Challenges
For decades, federal support for research has driven innovations that enhance national safety, competitiveness, and economic strength. However, recent federal funding cuts pose a threat to this progress. Understanding the implications of these cuts is vital for sustaining future advancements.
As scientists continue to unravel the complexities of disease emergence, the insights gained from this study could play a pivotal role in guiding public health strategies and resource allocation. The ability to predict which spillover events could lead to pandemics is a significant step forward in disease prevention and control.
