L20 Anti-HIV drugs Flashcards

1
Q

list important proteins involved in
HIV-host cell interaction

A
  • gp120
  • gp41:
  • CD4: A primary receptor on the host cell (typically T-cells) that binds to gp120.
  • CCR5: A coreceptor on the host cell used during the initial stages of infection.
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2
Q

Origin of HIV

A

HIV (Human Immunodeficiency Virus) originated from Simian Immunodeficiency Virus (SIV) found in primates. The virus likely crossed over to humans through the preparation and consumption of bushmeat.

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3
Q

Structure of HIV

A

HIV is a retrovirus with a roughly 9 kb RNA genome. Its structure includes:

Pol polyprotein: Contains protease, reverse transcriptase, and integrase enzymes.
Env polyprotein: Processes into gp120 and gp41, which are critical for viral entry into host cells.

(don’t need to know)
Gag polyprotein: Processes into matrix (MA), capsid (CA), nucleocapsid (NC), and P6
Accessory and regulatory proteins: These include six additional genes that assist in various stages of the viral life cycle and immune evasion ​​.

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4
Q

Life cycle of HIV 1/2.binding and fusion

A
  1. Binding and Entry:
    HIV binds to CD4 receptor on the surface of host cells (mainly T-cells) using gp120 protein. Binding induces a conformational change, allowing gp120 to interact with a coreceptor (CCR5 or CXCR4). Interaction exposes the gp41 protein, which facilitates the fusion of the viral and host cell membranes, allowing the viral RNA to enter the host cell.
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5
Q

Life cycle of HIV steps to know

A
  1. Binding
  2. Fusion
  3. Reverse Transcriptase
  4. Integration
  5. Maturation
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6
Q

Life cycle of HIV 3. Reverse transcription

A

Once inside, the viral RNA is reverse transcribed into double-stranded DNA by the viral reverse transcriptase enzyme.

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7
Q

Life cycle of HIV 4. Integration

A

The newly synthesized viral DNA is transported into the host cell nucleus and integrated into the host genome by the viral integrase enzyme.

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8
Q

Life cycle of HIV 5. maturation

A

After budding, the viral protease enzyme cleaves the Gag and Gag-Pol polyproteins into their functional forms, resulting in mature, infectious virions ​.

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9
Q

CD4/ CCR5/ CCR4

A

Helper T cells
C-C chemokine receptor 5;
initial infection
CXCR4 (C-X-C chemokine receptor
4; advanced disease)

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10
Q

gp120 and CD4 interaction

A

gp120-CD4 interaction → expose bind site for coreceptor (CCR5 or CXCR4)
Coreceptor binding → further conformational changes → expose gp41 and form channel for injection of HIV genetic material into the cell.
Then fusion process.

their interaction leads to a conformational change that will expose the binding sites for coreceptors (CCR5 or CXCR4). The coreceptor binding will lead to further conformational changes to expose gp41.

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11
Q

slow T cell depletion leads to ‘immune deficiency’ where they are

A

unable to fight against otherwise rare infections (opportunistic infections)

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12
Q

In a HIV host cell interaction there is also 2 factors

A
  • persistent viral replication
  • impair tumour immunosurveillance
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13
Q

CD4+T

A

Susceptible to HIV infection when there is a decline in CD4 leaving ppl more immunocompromised

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14
Q

Location on viral

gp120 and gp41

A

Found of surface of HIV particle and will interact with the host cell

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15
Q

HIV reverse transciptase is what type of dimer

A

heterdimer

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16
Q

Heterodimer of HIV RT
1. p66 subunit
2. p51 subunit

A
  1. catalytic role (polymerase and ribonuclease)
  2. structural role
17
Q

After the p66 subunit

RT in order

A
  1. RNA-dependent DNA polymerase: ssRNA → ssDNA
  2. ribonuclease (RNase H) - degrades RNA only if in the form of an RNA-DNA duplex
  3. DNA-dependent DNA polymerase: ssDNA → dsDNA
18
Q

HIV reverse transcriptase inhibitors

nucleoside reverse transcriptase inhibitors (NRTIs)

A
  • analogues of adenosine, cytidine, guanosine, or thymidine
  • phosphorylated to form a triphosphate - incorporated into ssDNA to terminate elongation. Bc they have no OH group for a phophodiester bond formation
  • first drug (zidovudine or azidothymidine; FDA, 1987) -don’t need
19
Q

Toxicity with nucleoside reverse transcriptase inhibitors (NRTIs)

A

GI disturbance, e.g., nausea, vomiting
* CNS effects, e.g., dizziness

20
Q

2 nucleoside reverse transcriptase inhibitor drugs

A
  • tenofovir disoproxil fumarate
  • tenofovir alafenamide
21
Q

Tenofovir metabolite drugs

A
  • Tenofovir is not pharm active and needs to be phosplated twice (already has one P-group so need 2 more to get 3)
  • Had no OH group so no phosphodiester bonds
22
Q

TDF and TAF are prodrugs of tenofovir - ↑ oral absorption however what is the difference between their prodrug actions

A

They are converted to tenofovir at different locations (plasma -TDF vs. intracellular-TAF)

23
Q

TDF and TAF from GI tract to plasma to lymphocytes

A
  • Both absoped orally
    In plasma
  • TDF is hydrolysed to tenofovir and because the drug is hydrophilic it will stay in plasma and not get redistributed into the tissues.
  • TAF is not hydrolysed
  • Both go to lymphocytes
  • TAF now hydrolysed → tenofovir and further → tenofovour monophosphaste → tenofovir diphosphate to inhibit HIV reverse transcriptase
24
Q

Tenofovir in plasma and systemic expore leads to what toxicities

A

renal toxicity and ↓ bone mineral density

25
Q

non-nucleoside reverse transcriptase inhibitors (NNRTIs)

A
  • distinct binding site – a hydrophobic pocket in the p66 subunit
  • conformational change → inhibit enzyme activity
  • Has a different binding site than the NRTIs
  • six FDA approved drugs - first drug approved in 1996
26
Q

what is HIV protease

Homodimer of what that cleaves what

A
  • homodimer of two 99-amino acid monomers
  • cleaves the Gag-Pol fusion polyprotein → into individual proteins
27
Q

PI= protease inhibitor

HIV protease inhibitors (PIs;-navir)

A
  • ten PIs approved by the FDA - most are peptidomimetics
  • first PI (saquinavir) approved by the FDA in 1995
  • combination antiretroviral therapy - NRTI + PI
  • CYP3A4-mediated metabolism
  • boosted PI - a PI + low dose ritonavir (a potent CYP3A4 inhibitor)

Cleave gag-pol fusion polyprotein

28
Q

HIV protease inhibitors drug toxicities

A
  • insulin resistance
  • hyperlipidemia
  • cardiovascular disease
29
Q

HIV integrase inhibitors

what is HIV integrase

A

A 288-amino acid protein - integrate the proviral DNA into the host cell genome

30
Q

HIV integrase inhibitor

HIV integrase strand transfer inhibitors (INSTIs; -tegravir)

A
  • bind to integrase and prevent DNA strand transfer
  • elvitegravir(FDA, 2012; fixed-dose combination only)

elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate
* extended-release injectable formulation

Don’t need to know about emtricitabine

31
Q

Anti-HIV drug development

  1. Single NRTI
  2. Dual NRTIs
  3. Triple (NRTIs + PI)
  4. NRTIs + (NNRTI or boosted PI)
  5. NRTIs + INSTI
A
  1. toxicity and resistance
  2. multidrug resistance
  3. multiple pills and varying dosing frequency (patient may forgot so not ideal)
  4. -
  5. single-pill fixed-dose combination

4 and 5 = HAART (highly active retroviral therapy)

32
Q

HIV/AIDS is now a manageable chronic disease - life-long ART
* Viral suppresion and undectable levels

A
  • viral suppression (< 200 copies/ml)
  • undetectable levels of viral load (< 20 copies/ml) = untransmittable (U=U)
33
Q

Initiation of HIV treatment

A
  • role of CD4+ cell count (< 350) in decision-making has changed (not based on this)
  • immediately following HIV diagnosis

But HIV may undergo mutations and multidrug res

34
Q

mode of transmission of HIV

  1. unprotected sexual contact
  2. blood-borne exposure
  3. perinatal transmission
A
  • Use condoms - highly effective in preventing HIV transmission and certain STIs
  • Treatment as prevention (TasP) - initiation of ART in seropositive individuals
  • PrEP (pre-exposure prophylaxis)
  • PEP (post-exposure prophylaxis)
  • needle and syringe programs
  • HIV screening and initiation of ART
  • CDC - avoid breastfeeding completely
    PrEP
35
Q

HIV

PrEP (pre-exposure prophylaxis)

A
  • individuals at high risk of infection and tested HIV-negative prior to initiation
  • taken daily; follow-up, HIV test, and
    prescription every three months
36
Q

HIV

PEP (post-exposure prophylaxis)

A
  • occupational and non-occupational settings
  • known or potential HIV exposure - initiate within 72 hours
  • 2 or 3-drug regimen - daily for 28 days