HIV

Question 1

HIV is latent (viral latency)
What does this mean?

Answer 1

is the ability of a pathogenic virus to lie dormant within in a cell
- it results from the lack of production of specific host cell proteins that are required for the activation of the viral genes responsible for turning on viral replication

Question 2

HIV is an example of retrovirus

Answer 2

• it carries the enzyme reverse transcriptase, which catalyses the synthesis of DNA from an RNA template
  (can undergo reverse transcription)

Question 3

what are the glycoproteins present in HIV

Answer 3

GP 120 and GP 41 (protruding glycoproteins) — interacts with CD4 receptor and co-receptor on the cell’s surface

Question 4

what kind of genome do HIV have?

Answer 4

they have two copies of single-stranded (+) sense RNA — they need RNA dependent RNA polymerase to produce a new RNA strand

Question 5

what is enclosed by the capsid?

Answer 5

• RNA
• RIP enzymes (reverse transcriptase, integrase and HIV protease)

Question 6

the binding and fusion of HIV

Answer 6

• binds to the outside of the T lymphocyte —> through the interaction between gp 120 and gp 41 (120 above 41) and CD4 receptor
• once attached, the virus enters the cell by fusing with the cell’s outer membrane, pushing its core of viral proteins into the cell body

Question 7

what does the viral core hold in HIV?

Answer 7

the virus’ genetic material (genome) and the three essential enzymes (RIP) —> they are essential for viral reproduction

Question 8

uncoating and reverse transcription

Answer 8

once inside the cell, the viral core uncoats, releasing its genetic material and enzymes
- reverse transcriptase then copies (reverse transcribes) the viral RNA genome into DNA which is compatible with the cellular DNA within the host cell’s nucleus

Question 9

integration of DNA

Answer 9

• the DNA copy of the viral genome is then transported to the cell’s nucleus
• the DNA copy of the virus enters the cell’s nucleus. the viral enzyme integrase inserts the viral DNA into the cell’s chromosomal DNA —> forming a provirus
• it may continue to stay dormat

Question 10

transcription

Answer 10

when activated, the virus uses the RNA polymerase to transcribe its viral genome back into viral RNA

Question 11

what does the transcribed viral RNA functions as?

Answer 11

mRNA for the synthesis of proteins and genomes for the next viral generation
(is + sense dna)

Question 12

translation, assembly and budding

Answer 12

the strands viral mRNA undergo translation
- resulting viral polypeptide chains are then cut into smaller pieces by the viral enzyme protease into functional proteins
- at this point, assembly begins —> the freshly cut proteins are assembled with viral RNA into many thousands of separate copies of the original viral core

Question 13

budding

Answer 13

each viral copy emerges from the host cell —> it invaginates by budding off from the cell membrane