Hemorrhagic Fever Viruses Objectives/Big picture only

Question 1

What are the flavivirdae viruses he discussed and what are their properties (transmission, enveloped, non enveloped, +/- RNA, DNA, segmented, etc)

Answer 1

Dengue and yellow fever

mosquitos

enveloped, non-segmented, + RNA

Question 2

Describe the replication scheme of Flaviviridae viruses.

Answer 2

Dengue and yellow fever:

1. receptor mediated endocytosis with pH dependent uncoating.
2. host ribosome translates +RNA to make single polypeptide.
3. polypeptide is cleaved by viral and host proteases
4. cleavage results in RdRP that replicates genome (+ to - to many ++++)
5. • RNA used to make structural proteins
6. virions assembled and bud into ER and are released at cell surface

Question 3

What are the Bunyaviridae viruses and what their properties?

Answer 3

enveloped, single strand, 2-3 segments, - RNA

Rift Valley fever (mosquitos infecting livestock and humans contact the animal blood or organs)
Crimean-Congo (ticks)
hemorrhagic fever with renal syndrome (rodents)

Question 4

Describe the replication of the bunyaviridae viruses.

Answer 4

1. endocytosed and uncoat with low pH
2. • RNA is transcribed into + RNA by the RdNP packaged in the virion
3. • cRNA translated into structural proteins and used to make many -RNA copies
4. virions packaged and bud

Question 5

What are the arenaviridae viruses and what are the properties?

Answer 5

Lassa Fever (“Old World”) and South American Hemorrhagic fever (“New World”)

transmitted by aerosolized rodent excreta

enveloped, segmented (2), ambisense RNA that contain host cell ribosome

Question 6

Describe the replication of arenaviridae.

Answer 6

“non-conventianal ambisense strategy”

1. pH dept endocytosis
2. Tx of only the NP and L parts of the genome (similar -RNA to +cRNA) using packaged RdRP
3. Tx of full copy of 2 segments
4. +cRNA used for structural proteins and template for viral genomes
5. virions packaged and released at cell surface

Question 7

What are the Filoviridae viruses and what are their properties?

Answer 7

Marburg and Ebola

transmitted by blood and fluids (contaminated needles and syringes)

enveloped, non-segmented, -RNA, and rod shaped

Question 8

Describe the replication of filoviridae.

Answer 8

1. endocytosis trigged by low pH and proteolytic processing
2. -RNA to +cRNA by viral RdRP
3. synthesis of proteins and -RNA copies
4. assembly of virions and released by bidding at cell surface

Question 9

What viruses can be transmitted human to human?

Answer 9

yellow fever, flioviruses (marburg and ebola)

Question 10

What is the most effective treatment for these viruses?

Answer 10

supportive care

*ribavirin has been shown to reduce severity of illnesses caused by arenaviruses (NOT ture for filovirus/ebola/marburg)

Question 11

How can rift valley fever virus be controlled?

Answer 11

immunizing livestock

Question 12

Do we have vaccinations for any of these viruses?

Answer 12

only yellow fever

Question 13

Hepacivirus is what type of virus?

Answer 13

flaviviridae

Question 14

T/F: Treat classis dengue with NSAIDs

Answer 14

F (“do NOT”)

Question 15

What are possible hosts for the yellow fever virus?

Answer 15

humans or non-human primates

Question 16

Can cause hemorrhagic hepatitis, encephalitis and retinal vasculitis (blindness)

Answer 16

Rift Valley (Bunyavirus)

Question 17

What is considered the greatest risk factor for severe dengue hemorrhagic fever?

Answer 17

secondary inf with another serotype

there are 4 serotypes, no overlapping immunity

Question 18

Can cause a mottled rash and metallic taste

Answer 18

classic dengue

Question 19

Viruses associated with causing a cytokine storm:

Answer 19

filovirus

Question 20

In a filovirus infection what a possible liver abnormality?

Answer 20

lesions containing filovirus nucleocapsid