Transmission of influenza viruses via aerosols or respiratory droplets

Professor Ron Fouchier, PhD, Professor of Molecular Virology, Department of Virology, Erasmus Medical Center Rotterdam, The Netherlands

Since its first detection in 1997, highly pathogenic avian influenza (HPAI) H5N1 virus has devastated the poultry industry of numerous countries of the Eastern Hemisphere. While human cases of infection have occurred, sustained human-to-human transmission has not been reported. What exactly determines aerosol transmission of influenza viruses in mammals has so far remained largely unknown.
We genetically modified A/H5N1 virus by site-directed mutagenesis and serial passage in ferrets. The mutated virus acquired the ability to transmit via aerosols or respiratory droplets. H5N1 virus required only a handful of mutations to become airborne in ferrets. Detailed knowledge and understanding of mutations and biological traits responsible for aerosol transmission may aid in early intervention strategies. Furthermore, the performance of diagnostic and surveillance tools, as well as the effectiveness of vaccines and antiviral drugs can be tested in the context of viruses with the most relevant genetic and biologic properties.

This study clearly provided new fundamental knowledge about aerosol transmission of influenza virus and tools for improved pandemic preparation but at the same time raised substantial concern related to biosafety and biosecurity. I will discuss the current state of affairs related to this work.