Respiratory viruses causing conditions like Covid-19 and flu are hard to control as they spread easily through the air. A new project between the Crick, Imperial and the Pirbright Institute asks if we can inactivate airborne viruses before they even reach a new host.
Electron micrograph image of influenza viruses. Credit: Cynthia Goldsmith, CDC. Image from: Public Health Image Library.
Preventing a virus from spreading from person to person is critical to stopping an outbreak in its tracks. Rachel Edgar, who runs a lab on infectious disease at Imperial College London and the Francis Crick Institute, is interested in how disrupting key viral pathways might prevent transmission of respiratory infections like influenza.
Before the COVID-19 pandemic, researchers at Imperial had developed a specialised ‘transmission tunnel’ to study how infectious influenza viruses move between hosts. More recent studies using this laboratory system showed that small solvent molecules called glycols are capable of inactivating a range of human viruses in airborne particles. The next challenge is to establish whether this promising approach can reduce the spread of airborne viruses beyond the laboratory.
“Molecules such as propylene glycol have been used safely around people for decades and are already found in a range of everyday products such as air fresheners and nasal sprays,” says Rachel. “We’re interested in understanding whether vaporised glycols could provide a practical, cost-effective way to reduce the amount of infectious virus circulating in the air and therefore help interrupt transmission.”
Supported by a grant from Flu Lab, Rachel and co-project lead Anika Singanayagam, a consultant virologist and researcher in adult infectious disease at Imperial, are now embarking on a quest to investigate whether glycol-based air treatments could be used to inactivate viruses like influenza before they infect people.
“The idea is to use glycol vapour proactively in crowded or poorly ventilated indoor spaces, for example, that pose a high risk of virus transmission,” says Rachel.
The team will investigate whether the glycol interventions can prevent the spread of influenza to human airway cells, and then between hamsters. Through collaborations at the Pirbright Institute, transmission interruption will subsequently be tested in pigs, due to the similarities between humans and pigs in infection response. The hope is that refining their experiments through the new project can reduce the need for future animal studies.
“Our goal should not be to expect to find a single solution that eliminates transmission,” says Anika Singanayagam, who also leads the National Respiratory Virus Reference laboratory at UK Health Security Agency. “Preventing infection at a population level will require a layered approach that combines multiple interventions. This work will help us understand whether reducing the amount of virus in the environment can play a meaningful role alongside measures such as vaccination, masks or air-cleaning technologies like ventilation.”
Because glycols act on the structure of pathogens as they travel through the environment rather than targeting specific strains, the researchers believe the findings of this study could have broader implications for other airborne infections, including future pandemic threats.
“A key advantage is that glycols inactivate a broad range of pathogens, so could be rapidly deployed to limit the spread of newly emerging infectious diseases in the environment, whilst other targeted therapeutics like vaccines are being developed,” concludes Rachel.
In the future, the researchers hope the programme will generate evidence to inform transmission studies in controlled human infection models and support the development of new public health interventions that reduce the transmission of respiratory infections.
