TABLE 1.

Summary of 9 human infectious diseases treated by approved drugs

Human virus	Yr of discovery/isolation	Animal reservoir(s)	Transmission route	Mean incubation period (range)	Mean viral particle diam (nm) (range)	Genome type,c length (kb)	Protein target(s) of approved drug(s)
HIV	1983	Chimpanzee, gorilla, sooty mangabey	Blood borne	8–11 yr	∼145 (95–166)	Linear (+)ssRNA, ∼9.8	Protease, RT, integrase, GP41, CCR5
HCV	1989	Unclear	Blood borne	∼7 wk (4–20 wk)	∼68 (45–86)	Linear (+)ssRNA, ∼9.6	NS3/4 protease, NS5A, NS5B polymerase
Human influenza virus	1933	Birds, pigs, horses	Respiratory	∼2 days (1–4 days)	∼120 (84–170)	Linear (−)ssRNA, ∼13.6	Matrix protein 2, neuraminidase, RNA polymerase
RSV	1957	No animal reservoir	Respiratory	∼5 days (3–8 days)	100–1,000	Linear (−)ssRNA, ∼15	RNA polymerase, glycoproteins
HBV	1963	Unclear (bats?)	Blood borne	90 days (60–150 days)	42–46	Circular dsDNA, ∼3.3	DNA polymerase
HCMV	1956	No animal reservoir	Blood borne	3–12 wk	150–200	Linear dsDNA, ∼230	DNA polymerase
HSV	Before 1900	No animal reservoir	Sexual or skin contact	∼4 days (2–12 days)	∼225 (209–239)	Linear dsDNA, 152–155	DNA polymerase, envelope proteins
VZV	1953	No animal reservoir	Respiratory	10–21 days	150–200	Linear dsDNA, ∼125	DNA polymerase, envelope proteins
HPV	1965	No animal reservoira	Skin-to-skin contact	∼2.9 mo (0.5–8 mo)	65–120	Circular dsDNA, ∼8	—b

^aPapillomaviruses have been widely found in birds, reptiles, marsupials, and mammals, whereas cross-transfer between species is rare (54).

^bInstead of targeting HPV proteins directly, three FDA-approved drugs (podofilox, sinecatechins, and imiquimod) act as immunomodulatory or antimitotic agents to treat external genital warts caused by HPV infections.

^c(+)ssRNA, positive-sense single-stranded RNA; (−)ssRNA, negative-sense single-stranded RNA; dsDNA, double-stranded DNA.