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Microbiology ` microbiology—Virology Microbiology ` microbiology—Virology SEcTioN ii 163

DNA viral genomes All DNA viruses have dsDNA genomes except All are dsDNA (like our cells), except “part-of-a-
Parvoviridae (ssDNA). virus” (parvovirus) is ssDNA.
All are linear except papilloma-, polyoma-, and Parvus = small.
hepadnaviruses (circular).

RNA viral genomes All RNA viruses have ssRNA genomes except All are ssRNA, except “repeato-virus” (reovirus)
Reoviridae (dsRNA). is dsRNA.
⊕ stranded RNA viruses: I went to a retro
(retrovirus) toga (togavirus) party, where
I drank flavored (flavivirus) Corona
(coronavirus) and ate hippie (hepevirus)
California (calicivirus) pickles (picornavirus).

Naked viral genome Purified nucleic acids of most dsDNA viruses (except poxviruses and HBV) and ⊕ strand ssRNA
infectivity (≈ mRNA) viruses are infectious. Naked nucleic acids of ⊝ strand ssRNA and dsRNA viruses are
not infectious. They require polymerases contained in the complete virion.

Viral envelopes Generally, enveloped viruses acquire their DNA = PAPP; RNA = CPR and hepevirus.
envelopes from plasma membrane when Give PAPP smears and CPR to a naked hippie
they exit from cell. Exceptions include (hepevirus).
herpesviruses, which acquire envelopes from Enveloped DNA viruses Have Helpful
nuclear membrane. Protection (Herpesvirus, Hepadnavirus,
Naked (nonenveloped) viruses include Poxvirus).
Papillomavirus, Adenovirus, Parvovirus,
Polyomavirus, Calicivirus, Picornavirus,
Reovirus, and Hepevirus.

DNA virus Some general rules—all DNA viruses:
characteristics
geNeral rUle commeNts
Are HHAPPPPy viruses Hepadna, Herpes, Adeno, Pox, Parvo,
Papilloma, Polyoma.
Are double stranded Except parvo (single stranded).
Have linear genomes Except papilloma and polyoma (circular,
supercoiled) and hepadna (circular,
incomplete).
Are icosahedral Except pox (complex).
Replicate in the nucleus Except pox (carries own DNA-dependent RNA
polymerase).

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