Quasispecies Dynamics Taught By Natural And Experimental Evolution Of Foot-And-Mouth Disease Virus

Foot-and-mouth disease virus (FMDV) exhibits high mutation rates and replicates as complex and dynamic mixtures of related mutants termed viral quasispecies. Here we review the basics of quasispecies theory, how FMDV helped to establish a link between theory and experimental observations, and some biological implications of quasispecies for the biology of FMDV. Topics covered include the relationship between genetic and antigenic heterogeneity, the escape strategy for long-term survival, memory in viral quasispecies, consequences of bottleneck events, evolution of host cell recognition, epidemiological fitness, evidence against the molecular clock hypothesis in virus evolution, internal interactions within mutant spectra, new antiviral strategies based on the error threshold concept, and a salient evolutionary transition towards genome segmentation when FMDV was subjected to many serial passages at high multiplicity of infection. The chapter illustrates that FMDV has been an excellent model system to unveil the potential of genetically variable viruses to find molecular pathways for survival under adverse environmental conditions.