New order recently created called the Mononegavirales . These include the families Paramyxoviridae, Rhabdoviridae and Filoviridae. . These are defined by the particular host cell infected, serological characterization, etc. Order, family, subfamily and general are capitalized and written in italics. Venacular terms for species etc. are written in Roman letters e.g. measles.
Species are virus strains that are recognizably different in more than one gene.
This excludes mutants. Example of species would be coxsackie viruses and polioviruses Species that exhibit readily apparent genetic similarity are grouped together into genera.e.g. Genera are grouped into families based on morphology, on the physical and chemical characteristics of the viral components, and on the molecular strategies used by the viral genomes to replicate. Other factors taken into account include antibody cross reactivity and serology. Bacterial viruses have been grouped into families based on structural characteristics.