Retroviruses

Question 1

Genome

Answer 1

Enveloped +RNA

encode RNA-dependent DNA polymerase (reverse transcriptase[RT])

Question 2

subfamilies

Answer 2

• Oncovirinae (HTLV-1,2,5); Cancer, neurological disorder
• Lentivirinae (HIV-1, HIV-2); slow, neurological disorders, immunosuppression
• Spumvirinae; nothing
• Endogenous viruses; retrovirus sequences that are integrated in the human genome (up to 8%)

Question 3

Structure

Answer 3

enveloped
spherical
8-120 nm

Question 4

genome feature

Answer 4

2 identical copies of +RNA

Question 5

HIV virion structure

Answer 5

Truncated cone

Question 6

HIV Attachment

Answer 6

Binds CD4 on T cells
also binds CCR5 on certain T cells
Fusion though gp41

Question 7

HIV Early Phase Replication

Answer 7

entry by fusion, genome release

RT makes complementary -DNA, then synthesizes +DNA, enters nucleus and is integrated into host genome by intergrase

Question 8

HIV Late Phase Replication

Answer 8

Full length RNA produced, which then makes mRNAs and proteins for new virion.
Envelopment and release at plasma membrane or through syncytia. HIV does not have to kill cell. requires cleavage of Gag and Gag-Pol

Question 9

HIV-1 genotypes

Answer 9

M (most common)
N
O
P

Question 10

HIV evasion tactics

Answer 10

infection of Lymphocytes and Macrophages (inactivates key parts of immune defense)
CD4 T cell infection (syncytia,apoptosis, loss of activation and control of immune system)
Antigenic Drift
Direct cell to cell spread

Question 11

3 Stages

Answer 11

1: Acute infection: resembles flu + rash
2: Persistence: Chronic Lymphadenopathy +fever, weight loss, fatigue
3: Reduction in CD4 T Cells <500/uL (increased virus in blood)

Question 12

After Stage 3?

Answer 12

FULL-BLOWN AIDS
CD4 T Cell count <200/uL
Virus load >75,000 copies/mL

Question 13

Oppurtunistic infections

Answer 13

Th17 depletion leads to fungal and bacterial infection

Th1 depletion leads to viral and intracellular bacterial infections

Question 14

Clinical syndromes

Answer 14

one of the most devastating epidemics ever.
HIV progresses from asymptomatic to profound immunosuppression called “AIDS”
-oppurtunistic infections
-cancers
-direct effect of HIV on CNS

Question 15

Transmission

Answer 15

Blood
Sex
Perinatal

Question 16

At risk?

Answer 16

Drug users, many partner sex, prostitutes, newborns of infected mothers, blood and organ transplant pre-1985

Question 17

Diagnosis

Answer 17

ELISA, western blot, Virion RNA RT-PCR, Real-time RT-PCR, CD4 cell counts + CD4:CD8

Question 18

Treatment

Answer 18

Many Many options, combinations for less chance of resistance.

Highly Active Antiretroviral Therapy very important

Question 19

prevention

Answer 19

education on safe sex, blood +organ donation screening, antiviral drugs, sterile needles.

Question 20

Vaccine difficulty

Answer 20

primary targets are different between clades and species.

Question 21

Vaccine developement

Answer 21

-Prime T cell response via vaccinia, canarypox, defective adenovirus vectors containing gp160 (env) gene (DNA vaccine). protein gp120/160 to activate B cells.