Heterogeneity and Collective Interactions Within Viral Populations.

The existence of viruses as obligate intracellular parasites with high mutation rates sets them apart from other forms of life in fundamental ways. Frequent errors in replication and assembly processes give rise to substantial genetic and genomic diversity within viral populations. The diverse constituents of viral populations often interact within and across infected cells, giving rise to complex emergent phenotypes and genetic interactions. This review examines the causes and consequences of viral population diversity and explores how the complex collective interactions among viral genomes in cells and tissues blur the definition of individuality and influence patterns of viral replication and evolution across multiple biological scales.