HIV

Question 1

Highest risk to contract HIV?

Answer 1

MSM who inject drugs

Question 2

Risk of transmission?

Answer 2

Mother to child at birth - 12-40%
Receptive anal sex - 3%
Use of contaminated injecting equipment - 0.6% 
HCW percutaneous puncture - 0.3%
Other kinds of sex <0.1%

Question 3

Factors which increase risk of transmission?

Answer 3

STIs - esp. HSV, Syphilis and chancroid

High plasma viral load

Question 4

Factors which reduce transmission?

Answer 4

Condom barrier protection
Circumcision
CCR-5 Delta32 homozygosity

Question 5

Diagnosis of HIV?

Answer 5

ELISA - antigen-antibody test
Western blot

HIV plasma viral load if early

Question 6

HIV virology

Answer 6

Origin from primate SIV viruses

HIV-1

• Subtypes - M, N, O, P
• M = majority
• MB = western world
• MC = Africa

HIV-2
- Western Africa

Question 7

Cells infected with HIV?

Answer 7

CD4+ T cells
Macrophages and monocytes
Dendritic cells

Question 8

Entry of HIV into cells?

Answer 8

gp120 attaches to CD4+

• -> Conformational change in the envelope
• -> Co-receptor binding - CXCR-5 or CCR-5
• -> gp41 spikes cell membrane
• -> complete fusion of viral particle with cell

Question 9

Humoral response to HIV?

Answer 9

B-cells produce antibodies against surface proteins –> antbodies against intracellular components

CD-8 cells produce cytotoxic response to infected cells

Question 10

Natural history of HIV infection?

Answer 10

Primary infection with HIV

• -> Acute HIV syndrome - 6-12 weeks post primary infection
• Reduced T cell counts
• High HIV viral count –> seeding of body
• Flu-like illness

Clinical latency - 12 weeks to 10yrs

• Control of HIV
• Slow loss of CD4+ T cells

AIDS

• T cells <200
• Constitutional symptoms
• Opportunistic infections

Question 11

Opportunistic infections and cell count?

Answer 11

Any = TB

<500

• VZV
• Candidiasis
• Hairy leukoplakia
• Kaposi’s sarcoma
• HSV
• NHL
• Cryptosporidiosis

<200

• PCP
• Toxoplasmosis
• Cryptococcus
• MAC
• CMV

Question 12

Mechanisms of CD4+ depletion?

Answer 12

Direct infection of cells

Infection of CD4+ progenitor cells –> reduced production

Attack from CD8+ cells

Immune activation from opportunistic infections

Question 13

Factors which predict poor prognosis

Answer 13

Co-infection with CMV
High viral loads
Extremes of age
No immune reconstitution with HRT

Question 14

Factors which improve prognosis

Answer 14

Weakened viral strains
CCR-5 viruses
CCR5 delta32 mutations in host
High titre neutralising antibody
High level CD8+ specific T cells
High level CD4+ specific responses

Question 15

Life expectancy with HIV

Answer 15

Nomral in patients who attain viral suppression and a CD4+ count >350 within 1 year of ART

Question 16

When to start ART?

Answer 16

At diagnosis

Question 17

What ART combination to use?

Answer 17

Tenofovir + emtricitabine
\+ Raltegravir OR
\+ Dolutegravir OR
\+ Elvitegravir/cobicistat OR
\+ Darunavir/ritoniavir

OR

Abacavir + lamivudine + dolutegravir

Question 18

What must you test for before commencing abacavir?

Answer 18

HLA-B5701

–> strong association with hypersensitivity reaction

Question 19

What is virologic failure?

Answer 19

HIV RNA >200 after 24 weeks of treatment
OR
Rebound HIV RNA >200 after viral suppression

Question 20

Side effects of Tenofovir?

Answer 20

Renal toxicity:

• Fanconis
• CRF

Osteoporosis

Question 21

Side effect of Abacavir?

Answer 21

Hypersensitivity reaction
GIT symptoms, rash, cough, luekopenia

HLA-5701

Question 22

Side effects of Protease inhibitors - darunavir?

Answer 22

MIs

Inhibit P450 - beware of drugs - statins, benzodiazepines

Question 23

PrEP regime?

Answer 23

Daily tenofovir + emtricitabine

Question 24

Effects of HIV on HCV infection?

Answer 24

Increases likelihood of chronic infection
HIgher HCV viral loads
Accelerated cirrohosis
Increased morbidity and mortality

= treat HCV infection

Question 25

HIV sanctuary sites?

Answer 25

Brain
Testes
GIT
Lymph nodes