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Microbiology ` microbiology—Virology Microbiology ` microbiology—Virology SEcTioN ii 167

RNA viruses All replicate in the cytoplasm (except retrovirus and influenza virus). “Retro flu is outta cyt (sight).”
Viral Family eNVeloPe rNa strUctUre caPsiD symmetry meDical imPortaNce
Reoviruses No DS linear Icosahedral Coltivirus —Colorado tick fever
a
Multisegmented (double) Rotavirus—cause of fatal diarrhea in children
Picornaviruses No SS ⊕ linear Icosahedral Poliovirus—polio-Salk/Sabin vaccines—IPV/OPV
Echovirus—aseptic meningitis
Rhinovirus—“common cold”
Coxsackievirus—aseptic meningitis; herpangina
(mouth blisters, fever); hand, foot, and mouth
disease; myocarditis; pericarditis
HAV—acute viral hepatitis PERCH
Hepevirus No SS ⊕ linear Icosahedral HEV
Caliciviruses No SS ⊕ linear Icosahedral Norovirus—viral gastroenteritis
Flaviviruses Yes SS ⊕ linear Icosahedral HCV
Yellow fever a
Dengue a
St. Louis encephalitis a
a
West Nile virus —meningoencephalitis, flaccid
paralysis
Zika virus a
a
Togaviruses Yes SS ⊕ linear Icosahedral Toga CREW—Chikungunya virus (co-infection
with dengue virus can occur), Rubella, Eastern
and Western equine encephalitis

Retroviruses Yes SS ⊕ linear Icosahedral Have reverse transcriptase
2 copies (HTLV), HTLV—T-cell leukemia
complex HIV—AIDS
and conical
(HIV)
Coronaviruses Yes SS ⊕ linear Helical “Common cold,” SARS, MERS
Orthomyxoviruses Yes SS ⊝ linear Helical Influenza virus
8 segments
Paramyxoviruses Yes SS ⊝ linear Helical PaRaMyxovirus:
Nonsegmented Parainfluenza—croup
RSV—bronchiolitis in babies
Measles, Mumps
Rhabdoviruses Yes SS ⊝ linear Helical Rabies
Filoviruses Yes SS ⊝ linear Helical Ebola/Marburg hemorrhagic fever—often fatal.
Arenaviruses Yes SS ⊕ and ⊝ Helical LCMV—lymphocytic choriomeningitis virus
circular Lassa fever encephalitis—spread by rodents
2 segments
Bunyaviruses Yes SS ⊝ circular Helical California encephalitis a
3 segments Sandfly/Rift Valley fevers a
Crimean-Congo hemorrhagic fever a
Hantavirus—hemorrhagic fever, pneumonia
Delta virus Yes SS ⊝ circular Uncertain HDV is a “defective” virus that requires the
presence of HBV to replicate
a
SS, single-stranded; DS, double-stranded; ⊕, positive sense; ⊝, negative sense; = arbovirus, arthropod borne (mosquitoes, ticks).

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