Retroviruses Flashcards Preview

Year 3: CSP & PH > Retroviruses > Flashcards

Flashcards in Retroviruses Deck (13)
1

What is a retrovirus?

> Unique enzyme (reverse transcriptase) which generates a DNA intermediate which is then integrated into the host genome (called a provirus)
> New viral genomes produced by cellular transcriptional machinery

2

Describe the genomic organisation of retroviruses

Gene order in all retroviruses is always the same —

5’ — gag - pol - env — 3’

Gag: codes for proteins which make up the matrix, capsid, and nucleoprotein structures
Pol: codes for reverse transcriptase and integrase and protease enzymes
Env: codes for the surface and transmembrane components of the viral envelope protein (Env)

3

Explain the role of reverse transcriptase in retroviruses

transcription of viral genome RNA to DNA

4

Explain the role of integrase in retroviruses

integration of the ds DNA into the host genome to form the provirus

5

Explain the role of protease in retroviruses

following release of new virion, cleavage of certain proteins is required for viral maturation (required to enter next host cell) and infectivity

6

What is the function of the 'gag' gene in retroviruses?

Gag: codes for proteins which make up the matrix, capsid, and nucleoprotein structures

7

What is the function of the 'pol' gene in retroviruses?

Pol: codes for reverse transcriptase and integrase and protease enzymes

8

What is the function of the 'env' gene in retroviruses?

Env: codes for the surface and transmembrane components of the viral envelope protein (Env)

9

Give examples of viruses that are associated with the development of cancer

> EBV
> Kaposi’s sarcoma-associated herpesvirus (KSHV)
> Human papilloma virus (HPV)
> HBV/HCV
>Merkel cell polyomavirus >Human T-cell leukemias virus type 1 (HTLV-1)

10

What can infection with HTLV-1 cause?

Adult T-cell leukaemia, HTLV-1 associated myelopathy (HAM, AKA tropical spastic paraparesis)

11

Where is the virus HTLV-1 endemic?

Central + South America
The Caribbean
Melanesia
Central + South Africa

12

What can infection with HTLV-2 cause?

Hairy cell leukaemia (with latency of 20-30 years)

13

What is hairy cell leukaemia?

Leukaemia cells collect in the spleen and cause splenomegaly
and marrow can't produce enough normal WBCs --> infection susceptibility. Associated with HTLV-2 infection