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164 SEcTioN ii Microbiology ` microbiology—Virology Microbiology ` microbiology—Virology

DNA viruses All replicate in the nucleus (except poxvirus). “Pox is out of the box (nucleus).”
Viral Family eNVeloPe DNa strUctUre meDical imPortaNce
Herpesviruses Yes DS and linear See Herpesviruses entry
Poxvirus Yes DS and linear Smallpox eradicated world wide by use of the live-
(largest DNA virus) attenuated vaccine
Cowpox (“milkmaid blisters”)
Molluscum contagiosum—flesh-colored papule with
central umbilication
Hepadnavirus Yes Partially DS and circular HBV:
ƒ Acute or chronic hepatitis
ƒ Not a retrovirus but has reverse transcriptase
Adenovirus No DS and linear Febrile pharyngitis A —sore throat
A Acute hemorrhagic cystitis
Pneumonia
Conjunctivitis—“pink eye”
Gastroenteritis
Myocarditis

Papillomavirus No DS and circular HPV–warts (serotypes 1, 2, 6, 11), CIN, cervical
cancer (most commonly 16, 18)
Polyomavirus No DS and circular JC virus—progressive multifocal leukoencephalopathy
(PML) in HIV
BK virus—transplant patients, commonly targets kidney
JC: Junky Cerebrum; BK: Bad Kidney
Parvovirus No SS and linear B19 virus—aplastic crises in sickle cell disease,
(smallest DNA virus) “slapped cheek” rash in children (erythema
infectiosum, or fifth disease); infects RBC precursors
and endothelial cells Ž RBC destruction Ž hydrops
fetalis and death in fetus, pure RBC aplasia and
rheumatoid arthritis–like symptoms in adults

Herpesviruses Enveloped, DS, and linear viruses
VirUs roUte oF traNsmissioN cliNical sigNiFicaNce Notes
Herpes Respiratory Gingivostomatitis, keratoconjunctivitis A , Most commonly latent in trigeminal
simplex secretions, saliva herpes labialis (cold sores) B , herpetic ganglia
virus-1 whitlow on finger, temporal lobe encephalitis, Most common cause of sporadic
esophagitis, erythema multiforme encephalitis, can present as altered
mental status, seizures, and/or
aphasia
Herpes Sexual contact, Herpes genitalis C , neonatal herpes Most commonly latent in sacral
simplex perinatal ganglia
virus-2 Viral meningitis more common
with HSV-2 than with HSV-1

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