Table 17.1.

Distinguishing Characteristics of Four Families of the Order Mononegavirales

Characteristic	Family Paramyxoviridae	Family Rhabdoviridaea	Family Filoviridae	Family Bornaviridae
Genome size (kb)	15–19	11–15	19	9
Virion morphology	Pleomorphic	Bullet-shaped	Filamentous	Spherical
Site of replication	Cytoplasm	Cytoplasm	Cytoplasm	Nucleus
Mode of transcription	Polar with nonoverlapping signals (except pneumoviruses) and stepwise attenuation	Polar with nonoverlapping signals and stepwise attenuation	Polar with nonoverlapping signals and stepwise attenuation	Complex with mRNA splicing and overlapping start/stop signals
Host range	Vertebrates	Vertebrates, insects, and plants	Humans, nonhuman primates, pigs, and bats	Horses, sheep, cats, birds, (humans?) shrews and possibly other small mammals
Pathogenic potential	Mainly respiratory disease	Mild febrile to fatal neurological disease	Hemorrhagic fever	Immune-mediated neurological disease in mammals
				Proventricular dilation syndrome in birds

^aVertebrate virus members.