HIV medicine

Question 1

What are the three stages of HIV infection if left untreated?

Answer 1

Acute HIV syndrome (conversation illness)
Clinical latency
AIDS

Question 2

Describe the HIV viral load over the natural history of HIV infection from acute infection to death?

Answer 2

Initially spike very high with acute infection
Then reduced as the immune system regains control

Over the period of clinical latency, viral load streadily increases

During AIDs the viral load can progressivly increase more and more rapidly

Question 3

Describe the CD4 cell count over the natural history of HIV infection from acute infection to death?

Answer 3

Initially goes very low (often into AIDs range) during acute infection
then recovers to somewhat normal levels
gradual decrease over the clinical latency period until reaches aids levels

Question 4

Symptoms of HIV seroconversion illness?

Answer 4

Non specific syndrome of pharyngitis, lymphadenopapthy, maculopapular rash

Note this presentation can be caused by essentially any other viral infection

Question 5

What is the definition of AIDS?

Answer 5

Aid defining illness
- opportunistic infection
- malignancy

CD4 cell count <200 (0.2)

Question 6

PJP is one of the AIDS defining infections. How does it present?

Answer 6

This is a gradual onset atypical pneumonia

Often pts present with gradual onset of fatigue, dysponea and constitutional symptoms over days to weeks (usually 2-3 weeks)

Question 7

How is PJP infection prevented? how is it treated?

Answer 7

Bactrim prophylaxis
Bactrim treatment

Question 8

What conditions commonly occurs at CD4 level of 0.2 (200)?

Answer 8

PJP infection
Canadiasis
Kaposi sarcoma

Question 9

How does kaposi sarcoma typically present?

Answer 9

Violaceous papular rash over the skin is the typical presentation
however these papules can occur in the GIT and lungs too -> can present with GI bleeding / haemoptysis

Question 10

What virus is associated with kaposi sarcoma?

Answer 10

Human herpes virus 8
- KS is strongly driven by oncogenic effects of virus

Question 11

What conditions commonly occurs at CD4 level of 0.1 (100)?

Answer 11

Cerebral toxoplasmosis
Cryptococcosis
- cryptococcal meningitis is one of the leading causes of mo0rtality in HIV/AIDS (globally)
Crypotosporidiosis
- chronic diarrhea

Question 12

What are the imaging features of cerebral toxoplasmosis?

Answer 12

CTB with contrast showing ring enhancing lesion in brain

Question 13

What is immune reconstitution syndrome and how is it implicated in HIV/AIDS affected pts with cryptococal meningitis?

Answer 13

Immune reconstitution is when HAART is given and the immune system is switched back on
In response to the pre-existing infections, there is a massive immune response causing damage

In pts with cryptococcal meningitis, antibiotics can steralise the CSF however there is often still fungal polysacarides present in the CNS (antigen)
If HAART is given to early, cause cause massive CNS inflammation and worsen the condition

Question 14

What conditions commonly occurs at CD4 level of 0-0.05 (essentially 0 -50)?

Answer 14

CMV retinitis/ CMV colitis
Micobacterium avium complex (MAC)
PML (reactivation of JC virus)
Primary cerebral lymphoma

Question 15

Explain how molecular pathophysiology opf HIV infection? (ie binding, cell entry, transcription etc) How

Answer 15

HIV binds using CD4 receptor and chemokine receptor (2 things needed), then enters the cell

HIV contains a reverse transcriptase which transcribed HIV RNA into pro viral DNA in the cytoplasm

This pro viral DNA is then integrated into host nucleus by HIV integrase and is replicated with host DNA

The HIV RNA from the normal DNA replication process is converted to HIV proteins.

HIV protease is used to package them and HIV exits the cell

Question 16

What are the two main classes of ARTs used in HIV?

Answer 16

Nucleo(s)tide reverse transcriptase inhibitors (NRTIs)
Integrase strand transfer inhibitors (INSTIs)

Question 17

When should HIV ART be started?

Answer 17

Should be started as soon as Dx is made (assuming pt consents). Should not wait for CD4 cell count to be a certain level etc

Question 18

What is the mainstay of initial ART therapy for HIV?

Answer 18

Tripple therapy
- Backbone of 2x NRTIs PLUS
- anchor / core drug which is one of the other 3 classes of drugs (usually INSTI)

Question 19

What are the two main consideration when choosing HIV regime?

Answer 19

Efficacy and robustness:
- Efficacy - what will allow me to control the viral load as quickly as possible
- Robustness - what will allow the least change / interruptions to their medications

Question 20

What HLA is associated with hypersensitivity to Abacovir?

Answer 20

HLA B 5701
- Abacavir is contraindicated in pts with HLA B 5701

Question 21

What is a common HIV regime?

Answer 21

Tenofovir (TAF) + emtricitabine (FTC) + Bictegravir (BIC)
- sold as single table formulation BIKTARVY

Question 22

What is a relative contraindication for Abacovir?

Answer 22

Cardiovascular disease / risk

Question 23

What is the two drug regime for HIV? In whom is a 2 drug regime appropriate for for treatment of HIV infection?

Answer 23

Dolutegravir and Lamivudine

There is evidence that this two drug regime is as good as a three drug regime but only in certain people:
- Cant have HBV or HCV infection
- Cant have any known resistance mutation (ie if have resistance to lamivudine then you are basically on mono therapy dolutegravir which doesnt work)
- Cant use in pts with high viral load

Question 24

Which HIV drug is associated with AKI?

Answer 24

Tenofavir disoproxil is associated with progressive decline in renal function due to tubolopathy

Dolutegravir is associated with rapid rise in creatinine without actually affecting renal fuinction
- once ceased, Cr returns to normal

Question 25

Why is treatment of coinfection with HIV and HBV difficult? What regime is used?

Answer 25

Because if just treat HBV, then this can encourage resistance to some agents that are used for HBV treratment but also can be used for HIV treatment

But if just treat HIV then will have immune reconstitution syndrome of HBV

So must treat both at once
This is often done using TAF + FTC + BIC (Biktarvy)

Question 26

Are people with HIV and high viral load more likely to get covid infection?

Answer 26

No

However if there is a low CD4 count then yes they are more likely

Question 27

What is the only PBS approved PrEP drug for HIV?

Answer 27

Tenofavir disoproxil + entracitibine

Question 28

What testing is routinely required for diagosis / workup of HIV?

Answer 28

Immunovirological
- HIV serology (screening and confirmatory)
- HIV 1 RNA plasma viral load
- CD4 count
- HIV 1 resistance genotype

Specialized testing:
- HLA B 5701
- Tb - IGRA (latent TB)

Question 29

What are the components of HIV serology?

Answer 29

HIV serology involves a highly sensative screening test and highly specific confirmatory test

Screening test:
- HIV abs + HIV1 p24 ag

Confirmatory test:
- HIV1 western blot OR NAAT (PCR based assay)