For the 1970 British film, see Permissive (film). For the grammatical mode, see Permissive mood. For the flavor of software license, see permissive free software licence.

A permissive cell or host is one that allows a virus to circumvent its defenses and replicate. Usually this occurs when the virus has modulated one or several of the host cellular intrinsic defenses and the host immune system. The permissive state of a host has now been determined to be the primary factor in determining whether a virus will cause pathological symptoms in a host.[1]

Susceptible versus permissive

The significance between the difference of the two has now been elucidated with study of the rabbit-lethal myxoma virus. Many species of rabbit cells in culture (without the presence of any antiviral defenses that would normally be in a host) can be infected by the myxoma virus, causing infection and cell death. However, inoculation of the myxoma virus in many species of rabbit shows that only one species of rabbit is affected, the rest being completely unharmed by the virus (lack of even viral shedding). This has been determined to be a result of the myxoma virus's inability to suppress other species' interferon expression, and hence resulting in the interferon in turn suppressing the myxoma virus.

This is a result of the positive susceptibility of many species of rabbit's cells, but negative permissibility of all but one of the rabbit species' cells.[2]


  1. N.J. Dimmock et al. "Introduction to Modern Virology, 6th edition." Blackwell Publishing, 2007.
  2. Nash P. et al. "Immunomodulation by viruses: the myxoma virus story." Immunol Rev. 1999 Apr;168:103-20.
This article is issued from Wikipedia - version of the 3/4/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.