Table 1.

Virus classification system (Baltimore groups).

Group	Acronym	Members
I	dsDNA	Double-stranded DNA viruses
II	ssDNA	Single-stranded DNA viruses
III	dsRNA	Double-stranded RNA viruses
IV	ssRNA(+)	Positive-sense single-stranded RNA viruses
V	ssRNA(-)	Negative-sense single-stranded RNA viruses
VI	ssRNA-RT	RNA reverse-transcribing viruses
VII	dsDNA-RT	DNA reverse-transcribing viruses