Microviruses at a bacterial cell wall, illustration. A group of microviruses are arriving to infect an Escherichia coli bacterium. Microviruses are a family of icosahedral bacteriophages (viruses that infect bacteria). They are round, non-enveloped viruses, with a single-stranded deoxyribonucleic acid (DNA) genome. Their name refers to the fact that they have one of the smallest viral DNA genomes. The spike proteins (blue) allow the viruses to recognise, bind, and infect their bacterial host cells.