As well as mutating rapidly, the virus has its own counter defences, producing a protein called viral infectivity factor (Vif) which tricks the body into destroying its own APOBEC3 enzymes.
PsycoTrace, on successful malware detection, lacks malware counter-defence mechanisms.
In turn, viruses activate counter-defence mechanisms to circumvent host antiviral RNA silencing mechanisms by expressing RNA-silencing suppressors or adopting silencing-resistant RNA structures.
(See Byrne and Hilbert 2007 for a defence of this criticism, among a set of other criticisms; see also Campbell 2005 for a counter-defence).
In this study, we examined the effect of cisplatin on PAFR expression in ovarian cancer cells to explore the possibility of a counter-defence mechanism.
Moreover, such counter-defence mechanism is supported by the assumption of a strong co-evolution between proteases and protease inhibitors which are mutually released during a pathogen-host interaction [ 122].
In addition, previous studies have shown that P. fluorescens and Φ2 undergo persistent antagonistic coevolution (reciprocal adaptation of host defence and parasite counter-defence) [ 30- 32], whereas no such coevolution has been observed between PP7 and P. aeruginosa [ 33]; here phage persist on a subpopulation of susceptible hosts that is maintained because of the cost of resistance [ 34].
Antagonistic host-parasite coevolution, the reciprocal evolution of host defence and parasite counter-defence, can drive patterns of biodiversity [ 1- 5], host and parasite population dynamics [ 6], the evolution of parasite virulence [ 7, 8], and may impose selection for the maintenance of sexual reproduction [ 9].
In this context, a defence-counter-defence mechanism was observed between the plant-pathogen interaction tomato/ Phytophthora infestans, in which both, host and pathogen are supposed to release specific sets of proteases and protease inhibitors mutually impairing each other [ 39, 121].
Similarly, there may be trade-offs against counter-defences in Daphnia.
This has important implications for our view on how toxic Microcystis blooms develop, which may not so much be the result of zooplankton grazing in general but rather may reflect the outcome of interactions between defences and counter-defences in auto- and heterotrophs, comediated by the costs imposed by both the development of these defences and counter-defences.
