Highly differentiated cultures of ferret airway epithelium for the study of respiratory viruses, including influenza.

To study the transmission of a virus from one host to another, the use of whole animals is ultimately unavoidable. However we can strive to make sure that the numbers of animals that are used are minimized and that the whole animal studies are complemented by the very best research in vitro. In that way, the answers gained from the whole animal studies tell a complete story and move the field on. We aim to understand why some influenza viruses transmit between people whilst others do not. This allows us to predict how and when influenza pandemics will arise. We use ferrets to achieve this. One ferret is infected with a known dose of virus and another animal is exposed to see if they catch the virus. This can tell us which viruses transmit but not why. Moreover many different strains of virus might be tested at many different doses before the right conditions for the experiment are found. Here we propose to develop a sophisticated cell culture model using the very same target cells as become infected in the animal, the cells of the nose and throat. In this way we can recapitulate in a test tube the environment the virus has to cope with in real life. What is more, from a single animal we can reproduce more than 50 equivalent test tube cultures to test different viruses side by side and look at the effects of drugs and other interventions on the virus.

Because the ferret and human respiratory system are similar, we predict that these ferret airway cultures will be useful for studying other human respiratory diseases.

Ferrets are extensively used as the gold standard animal model for influenza virus infection. In particular they have been used recently to study influenza transmission, an unsolved issue that is key to understanding the emergence of pandemics. Transmission experiments are costly in terms of whole animal use and although they can tell us which viruses transmit, in isolation, they do not reveal why. The target tissue in the bottle-neck process of influenza transmission is the respiratory epithelium. Here we propose to develop primary cultures of ferret airway epithelium that will recapitulate the environment the virus must traverse to initiate infection in the new host. These cultures will enhance our understanding of the virus:host interaction by allowing detailed cell and molecular biology using a wider panel of virus variants than would be possible in whole animal experiments. The results will allow an informed reduction in animal use whilst at the same time enhancing the scientific explanation of respiratory virus transmission . Moreover as other human and animal respiratory viruses may also replicate in these primary cultures, the development of the methodology will be of use to many other medical and veterinary scientists who study the respiratory organ both as a physiological system and as a pathogen target.