Bacteriophage Phi X 174 (Coliphage phi X 174; Enterobacteria phage phi X 174; Phage phi X 174; phi X 174 Phage)
The type species of the genus microvirus. A prototype of the small virulent dnacoliphages, it is composed of a single strand of supercoiled circular dna, which on infection, is converted to a double-stranded replicative form by a host enzyme.