Investigating the molecular mechanisms of dengue virus replication

Dengue, a viral disease spread by mosquitoes, poses a growing global health threat. Traditionally associated with tropical regions, the dengue virus is now appearing in parts of Europe. Although many infections cause only mild symptoms, dengue can progress to a severe and potentially fatal illness. With restricted vaccine availability and treatment limited to symptom management, there is an urgent need for effective antiviral therapies.

Developing therapies against dengue requires a detailed understanding of the virus life cycle. A key stage in this process is the assembly of new virus particles, which is thought to involve lipid droplets – multifunctional fat stores found within cells. Currently, the process is poorly understood but it could be a target for new treatments against dengue.

Researchers from the University of Bristol came to ISIS to explore the viral replication process in greater detail. Using small-angle neutron scattering, postdoctoral researcher Holly Stockdale, PhD student Hongye Li and Master’s student Leo Li investigated how dengue virus proteins interact with lipid droplets. Rather than taking a traditional biological approach, the team is investigating the problem through the lens of physical chemistry.

“We use simplified model systems, isolating the key components involved in viral assembly from the many other biological processes taking place within a cell,” explained Holly. “This allows us to focus on one specific stage of the viral replication process and gain a clearer understanding of its molecular mechanism.”

Recent evidence suggests that lipid droplets act as a platform for viral assembly, with capsid proteins, which form the virus’s protective shell, docking on the droplet surface, helping to form new virus particles. The team are particularly interested in finding out whether Plin3, a protein on the surface of the lipid droplets, is implicated in the process.

Working with ISIS scientist, Leide Cavalcanti, the Bristol team used the Zoom instrument as part of their broader research programme exploring the role of lipid droplets in dengue virus assembly. Their experiments at ISIS focused on characterising an artificial lipid droplet model system. The team took advantage of a technique called contrast variation, selectively replacing hydrogen with deuterium to make different key components more or less visible to neutrons. This allowed them to isolate individual components and gain detailed insight into the structure and behaviour of the model system for future studies of dengue virus protein interactions.

“We’re still at an early stage, but the data we’ve collected so far is promising,” said Hongye. “These neutron studies are helping us understand the bulk properties of the system. Our next step is to complement these experiments with surface-sensitive techniques, giving us a fuller picture of the interactions taking place.”

With a more comprehensive understanding of the role of lipid droplets in dengue virus assembly, new opportunities to interfere with the virus’s life cycle may emerge. The team’s neutron experiments are an important first step towards revealing this complex molecular picture and identifying avenues for further research.