 Also, an emerging concept that is gaining traction among some virologists is that of the virocell, in which the actual phenotype of a virus is the infected cell, and the virus particle is merely a reproductive or dispersal stage, much like pollen or a spore.The smallest viruses in terms of genome size are single-stranded DNA (ssDNA) viruses.Perhaps the most famous is the bacteriophage Phi-X174 with a genome size of 5386 nucleotides.