HIV

Question 1

What happens if WBC count goes down to <200?

Answer 1

Question 2

What happens if WBC goes down to 200-500 (in H|V)?

Answer 2

Question 3

What are the AIDS defining conditions?

Answer 3

AIDS - defining conditions:

• Recurrent bacterial pneumonia
• Pneumocystis pneumonia
• Fungal infections (e.g. candidiasis of oesophagus)
• Tumours and malignancies

E.g. Kaposi sarcoma (skin lesions) & primary lymphoma of the brain

Question 4

What antibodies tests would you do in HIV Ix?

Answer 4

A) Antibody test: antibodies against HIV

B) Antibody/antigen test: antibodies against HIV and HIV antigen (virus itself)

C) RNA/DNA test: screen for viral RNA -> detects virus directly & DNA -> copies of viral RNA

• Antibody/antigen test is recommended for screening purposes > better for identifying early infection
• The other tests are recommended as confirmatory tests (as follow up after positive result of antibody/ antigen test)

Question 5

What is the aim of anti-retroviral therapy?

Answer 5

Antiretroviral therapy (ART)

• combination of medicines (known as HIV regimen)
• slow down HIV replication -> help immune system to recover and fight other infections more effectively
• reduce number of viruses -> viral number is low

Question 6

General points in treatment with ART

Answer 6

• typical treatment regimen involves taking 2 - 3 of these medication at the same time (not one as with one usually the virus would get resistant; if few drugs given -> virus dies before it becomes resistant)
• before starting on the treatment -> test to what type of medication a person would be resistant to

(The types of ART act on different steps of viral entry into CD4+ cell/replication pathway)

Question 7

(6) names of classes of the drugs used as part of ART

Answer 7

• Fusion inhibitors
• CCR5
• Nucleoside Reverse Transctiptase Inhibitor
• non-nucleoside Reverse Transcriptase
• Integrase Inhibitor
• Protease Inhibitor

Question 8

MoA of fusion inhibitors

Answer 8

bind to GP120 protein on HIV virus -> virus cannot enter CD4+ cell

Question 9

MoA of CCR5 antagonist

Answer 9

binds to co-receptor on CD4+ cell -> so HIV virus cannot enter the cell

Question 10

MoA of Nucleoside Reverse Transcriptase Inhibitors

Answer 10

viral RNA cannot be converted into DNA (that could attach to host’s DNA) -> reverse transcriptase enzyme usually attaches nucleosides together to form a strand -> NRTI attaches itself to nucleosides and prevents other nucleosides to attach to each other

Question 11

MoA of Non-nucleotide Reverse Transcriptase

Answer 11

reverse transcriptase enzyme is prevented directly from acting on RNA (enzyme action inhibitor)

Question 12

MoA of Integrase Inhibitor

Answer 12

enzymes called viral integrase enzymes would attach viral DNA into host DN

-> Integrase inhibitor prevents viral integrase enzyme -> so virus cannot attach itself to the host’s DNA (the main trigger for cellular apoptosis)

Question 13

MoA of Protease Inhibitor

Answer 13

RNA polymerase would transcribe DNA (host + viral) into mRNA to produce proteins in ribosomes and protease enzymes would allow new proteins to be created