The merits of ferrets
Many insights into flu transmission have come from research on an unusual model organism – the ferret
In 1933 ferrets being used in work on a vaccine for distemper, a viral disease affecting many animals, contracted influenza from a researcher (and also managed to pass it on to another).
As a result of this the researchers were able to identify the influenza virus, and since then ferrets have been used as model organisms for human flu – they show similar symptoms to humans and a similar pattern of virus receptors along their respiratory tracts (unlike mice). They have been used to understand more about flu and to test new vaccines.
Ferrets were also used in controversial studies examining the potential for H5N1 avian flu to develop the capacity for airborne transmission. Human H5N1 was genetically modified in a variety of ways and modified strains were used to infect ferrets. During transmission in ferrets the virus acquired mutations that enabled it to undergo airborne transmission.
These studies, and others in which viruses have had ‘gain of function’ genetic changes introduced to promote airborne transmission, have proven highly controversial. Some argue that they are vital for understanding the biology of airborne transmission, so that strategies to counteract it can be developed. Others argue that they are far too dangerous – the consequences could be catastrophic if airborne strains escaped from labs or the technology was used by bioterrorists.
A voluntary moratorium on such research was introduced in 2012 but lifted in 2013. However, in October 2014 the US government ordered a temporary halt to ‘gain of function’ studies in dangerous pathogens such as influenza, a move opposed by some scientists.
Concern has also been raised about ‘gain of function’ studies on H7 avian influenza viruses – which in 2013 were found to cause severe disease in humans. Specific amino acid changes were identified that gave these viruses the capacity for airborne transmission – importantly, without loss of virulence.
Some researchers questioned whether these results should have been published – particularly given that the resulting viruses are suggested to be at least as virulent as the 1918 Spanish flu virus.Lead image:
Mark Probst/Flickr CC BY
- The ferret as a model organism to study influenza A virus infection (2011)
- Airborne transmission of influenza A/H5N1 virus between ferrets (2012)
- Experimental adaptation of an influenza H5 HA confers respiratory droplet transmission to H5 HA/H1N1 virus in ferrets (2012)
- News: Scientists brace for media storm around controversial flu studies
- News: H5N1 researchers announce end of research moratorium
- News: Viral-research moratorium called too broad
- Airborne transmission of highly pathogenic H7N1 influenza virus in ferrets (2014)
- An avian H7N1 gain-of-function experiment of great concern (2014)
Questions for discussion
- Do you think ‘gain of function’ experiments should be carried out?