Larger viral genome size facilitates emergence of zoonotic diseases

Emergence of new viral diseases is linked to mutation or recombination events. The likelihood of cross-species transmission is related to phenotypic plasticity of a virus and its capacity to produce genetically variable progeny. Herein a model is described connecting the production of genetic variability with increasing genome size. Comparing all known zoonotic viral genome sizes to known non-zoonotic viral genome sizes demonstrates that zoonotic viruses have significantly larger genomes. These results support the notion that large viral genomes are important in producing new zoonotic disease, and suggest that genome size may be a useful surrogate in screening for potential zoonotic viruses.