Stochastic extinction of viral infectivity through the action of defectorsJ. Iranzo and S. C. Manrubia
Centro de Astrobiología, CSIC-INTA - Ctra. de Ajalvir km. 4, 28850 Torrejón de Ardoz, Madrid, Spain, EU
received 7 August 2008; accepted in final form 24 November 2008; published January 2009
published online 16 December 2008
The high error rates of RNA viruses at replication suggest they might be close to the extinction threshold predicted by quasispecies theory. Hence, moderate increases in the mutation rate could drive them to extinction. In persistent infections of an RNA virus treated with a mutagen, it has been observed that infectivity eventually disappears, although the replicative ability of the virus is not affected. By means of a simple model that takes into account two phenotypic traits, we demonstrate that extinction is a purely stochastic phenomenon caused by the intermittent outbreaks of a defective, non-infective subpopulation. The transition between dynamics dominated by population fluctuations (finite system size N) and the mean-field behavior (N ) is characterized. We discuss the implications of this alternative pathway to viral extinction.
87.19.xd - Viral diseases.
87.10.-e - General theory and mathematical aspects.
87.23.-n - Ecology and evolution.
© EPLA 2008