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Standardising aerosol use in airway infection and vaccine studies
In the EU projects TRANSVAC2 and VetBioNet ERG, aerosols were frequently used in infection and vaccine studies. Project partners from 16 international institutes recently exchanged their experiences during a workshop meeting at Wageningen Bioveterinary Research (WBVR, part of Wageningen University & Research) in Lelystad. “By the use of aerosols, i.e. very fine droplets dispersed in the air, the natural infection route of respiratory infections is simulated. The added value of this knowledge exchange lies in the possible and necessary standardisation of aerosol administration in experimental studies,” says veterinary pathologist Norbert Stockhofe of WBVR.
Sixteen TRANSVAC2 and VetBioNet ERG partners met in Lelystad at the end of March. “Every partner organisation was represent. This created a lot of room for exchanging experiences on the use of aerosols and the techniques to generate and measure aerosols in the various European partner institutes,” says WBVR researcher Norbert Stockhofe, initiator of the workshop. Over the past five years, the group of international researchers studied the production of aerosols and their distribution in the respiratory tract after administration in infection and vaccine studies.
Variation
The use of aerosols by different researchers is very diverse. “It is difficult to get aerosols uniform and comparable between institutes and studies and then also achieve similar effects in the uptake of pathogens or vaccines.” The variation in aerosols makes it difficult to reproduce studies, but also to compare research properly.
Aerosols play an important role in the disease transmission of respiratory infections in particular. “Since Covid, everyone knows the importance of aerosols.” However, researchers are only moderately successful in simulating natural disease transmission via aerosols in research. “The great thing about this international collaboration has been that everyone recognises this problem. By using the joint knowledge of (veterinary) medicine, biology and physics, we are considerably more likely to find solutions for this.”
For example, the group discussed the various technical possibilities of nebulisers. "Which nebulisers are on the market and how do you use them? What measurement methods are there to ensure the administration and quality of aerosols during a study? By combining best practices, we can bring our trial design more in line with each other."
Knowledge
In addition to information about nebulisers, Stockhofe says knowledge about aerosols themselves has also increased thanks to the collaboration within the TRANSVAC2 and VetBioNet group. “Because of the importance of this route of infection, this is valuable information.” However, many questions remain, the research leader notes. “The required composition of an aerosol for disease transmission is highly dependent on the pathogen in question. And even then, you don't have a good picture of all the variables. Take Covid, for example. We know that the virus is transmitted through aerosols. We are able to detect genetic material in the droplets, but not to isolate the viable virus from the air droplets. The genetic material itself has no infectious properties. That fact leads to many additional questions about aerosols, their relationship to pathogens, the route of the aerosol in the host and environmental factors that may influence whether or not an infection will occur.”
Standardisation
Although a lack of information about aerosols persists, the European project partners agree that the knowledge gathered needs to be used to achieve some form of standardisation in the use of aerosols in infection and vaccine studies. "The more we do that and make our tests imitable and repeatable, the better. This allows us to better compare each other's results, and also validate the results with fewer tests in future," concludes Stockhofe.