Story about Ferrets
Ferrets are promising and robust animal models for studying human influenza. Numerous researches of comparative significance have been done on the ferrets since 1933. According to Fouchier et al, for example, A/Indonesia/5/2205 has been chosen as a potential HPAI (Highly Pathogenic Avian Influenza) H5N1 strain to generate mutations to obtain airborne transmissibility between mammals, after the tenth passage in ferrets (Herfst et al., 2012). The ferrets could get infection of the chimeric virus by aerosol transmission, without any direct contact, maintaining a low fatality compared with avian hosts.
Several reasons have been proposed by experts on experimental animals to explain why they chose ferrets instead of mice, primates, or even rabbits. First, they have the same distribution of a-2,6-linked sialic acid (SA) receptors in upper respiratory tract (URT), which is relatively similar as in humans. Fouchier claims that the specificity of SA receptors is partially responsible for the host restriction of replication and transmission of influenza A viruses, namely the fact that HPAI cannot cause pandemic formation in human hosts. Second, ferrets are susceptible to infection with both human and avian influenza viruses. This trait makes it easier to manipulate artificial viral infection by intranasal inoculation. Last, ferrets can transmit the viruses horizontally, with or without direct contact. Ferrets thus are capable of meeting the requirement for an ideal experimental condition. In contrast, mice, as well as primates, can hardly get disease when challenged. Rabbits have distinctive respiratory system among mammals. Ferrets are the most comparative models when compared with other candidates.
Herfst, S., Schrauwen, E. J. A., Linster, M., Chutinimitkul, S., de Wit, E., Munster, V., et al. (2012). Airborne transmission of influenza A/H5N1 virus between ferrets. Science, 336(6088), 1534-1541. doi:10.1126/science.1213362