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Spring, 2004 Lecture Outline

3/9 FILOVIRUSES, ARENAVIRUSES & BUNYAVIRUSES


Filoviruses
:

once in rhabdo family; morphologically different
long filaments in various shapes, U's & circles
infect range of mammals; reservoir is unknown

Marburg virus- fatal hemorrhagic fever
Ebola virus- severe hemorrhagic fever, mortality of 50-90%

symptoms & pathology; epidemiology


Arenaviruses:

lymphocytic choriomeningitis, Lassa fever, hemorrhagic fevers

structure: pleomorphic 100-300 nm

RNA- 2 segments (L & S), appear circular
**ambisense polarity- both plus & minus sense on RNA strands

transcription & replication:

strategy also applies to one grp in bunya family

S RNA segment:

genome(+/-) aaaaaaaaaa- aaaaaaaaaa| aaaaaaaaaaaaa+


transcription

(+)mRNA


translation

aaaaaaaaaaaaa replication

N protein

~~~~~~~~~~~~~~~

aaaaaaaaa

+ aaaaaaaaaa| aaaaaaaaaaaaa-


aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa transcription

replicationaaaa


aaaaaaaaaaaaa translation

aaaaa

~~~~~~~~~~~~~~~~ GPC protein

genome(+/-) aaaaaaaaaa- aaaaaaaa aa| aaaaaaaaaaaaa+


see also CRC, Fig. 190- Bunyaviridae, Phlebovirus

pathology: not cytolytic, cytotoxicity from T-cell attack

Tacaribe grp- spread to humans from rodent excreta
*Lassa fever- only one which can spread from human to human

cytopathology & treatment

 
Bunyaviruses: large grp- insect transmitted; usually in tropics

several spp in US; most common encephalitis virus in US
several prototypes- e.g.: Bunyamwera & Calif. encephalitis
transmission- mechanical spread by insect vectors

structure: enveloped 100 nm

RNA- 3 segments 6 x 106 d total; minus strands, except phlebovirus- ambisense like arenaviruses

replicated in cytoplasm; process similar to orthomyxo-

bud into Golgi- unique to bunya's

pathology: viremia follows bite; multiplies in susceptible organs
patchy inflammation, neuronal degeneration, edema in cortex

 

Next week:

dsRNA viruses: Reoviridae, Partitiviridae, Cystoviridae- see CRC, ch 7 & appropriate parts of Wagner, including ch 16, & on-line

Retroviridae- see CRC, ch 6 & appropriate parts of Wagner, including ch 20, & on-line

 

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 Updated 1/25/04 by thatcher@sonoma.edu