HIV, Hep B, Hep C

Question 1

What are the peripheral signs of HIV/immunocompromised?

Answer 1

Oral candidiasis, kaposi’s sarcoma, PCP: Pneumocystis carinii pneumonia

Question 2

Describe the principles of HIV structure

Answer 2

SsRNA, capsid, lipid envelope

Question 3

Briefly outline HIV replication

Answer 3

Reteroviruses = ssRNA –> DNA –> ssRNA within CD4 cells = T-helper, macrophages = destroys cell = inflam = infects more cells

Question 4

Outline the stages of HIV replication

Answer 4

1) binding and fusion by CD4 and coreceptors,
2) infection,
3) reverse transcription,
4) integration with host DNA by integrase,
5) transcription,
6) assembly of viral proteins,
7) budding of immature virus out of the cell,
8) immature virus breaks free of cell,
9) maturation: viral proteins cut by protease = working virus

Question 5

What 3 key enzymes are involved in HIV replication within a host cell?

Answer 5

Reverse transcriptase, integrase, protease

Question 6

How is HIV transmitted?

Answer 6

Contact with large quantities of body fluids = sexual, transfusion, needles, medical procedures, perinatal transmission

Question 7

Outline the stages of the HIV viral load

Answer 7

Primary infection: very high viral load, Ab response, can present like glandular fever.

Latent: (months-years) low viral load (lower = healthier the pt) CD4 count drops with the rise in viral load.

Symptomatic infect: CD4 count <350, infections present.

Severe/AIDS: <200

Question 8

What are the main symptoms of acute HIV?

Answer 8

Fever, weight loss, pharyngitis, myalgia, hepatosplenomegaly, nausea, vomiting, rash, lymphadenopathy

Question 9

What factors affect HIV transmission?

Answer 9

Types of exposure, viral load, condom use, breaks in skin/mucosa, other infections meaning the barriers are weaker

Question 10

Outline HIV testing

Answer 10

Serology: Ag and Ab, can pick up within 4 weeks.

PCR: detects HIV nucleic acids, expensive slower, not used for screening.

Rapid: Ab, finger-prick, <1hr

Question 11

Who should be tested for HIV?

Answer 11

Everyone if rate >2/1000

Question 12

Outline HIV treatment

Answer 12

To achieve and undetectable HIV load, reconstitute CD4 count, reduce inflam, reduce risk of transmission = 3 diff ARV anti-retroviral drugs to manage the level of mutations

Question 13

Why isn’t there a vaccine for HIV?

Answer 13

Constant mutation of envelope proteins

Question 14

What is an elite controller?

Answer 14

Able to manage HIV viral load more efficiently

Question 15

Apply the infection model to a patient with HIV and acquired immunodeficiency syndrome (AIDS)

Answer 15

Pathogens: viral, fungal, protozoal of particular concern.

Outcome: chronic infect or death (probable if diagnosed late/untreated)

Question 16

How is Hep B + C transmitted?

Answer 16

B: blood, sex, vertical. C: blood, sex

Question 17

Hep B structure

Answer 17

DsDNA, enveloped

Question 18

What are the symptoms of acute hep b?

Answer 18

Asymptomatic, jaundice, fatigue, abdominal pain, anorexia/nausea/vomiting

Question 19

How does Hep B serology change over time?

Answer 19

Surface Ag first, 
e-Ag, 
core Ab (IgM), 
e-Ab, 
surface Ab, 
core Ab (IgG)

Question 20

How do you know a chronic Hep B infection is present?

Answer 20

Test for surface Ag: +ve 6 months after = chronic

-ve surface Ab = not mounted good enough immune responce

Question 21

What is the treatment for Hep B?

Answer 21

No cure, life-long anti-virals but not required for inactive carriers

Question 22

Who is at risk of Hep C infection?

Answer 22

IV drug users, sexual contact, infants to HCV+ve mothers, blood transfusion prior to 1991

Question 23

What is the main diff between Hep B and Hep C?

Answer 23

Hep C = ~80% become chronically infected if untreated = liver disease, hepatocellular carcinoma, transplant, death

Hep B = vaccine

Question 24

Symptoms of Hep C?

Answer 24

80% asymptomatic, 20% vague symptoms

Question 25

Hep C blood test?

Answer 25

Serology: Ab only, viral PCR

Question 26

Hep C treatment?

Answer 26

CURE: anti-viral drug combo, 8-12 weeks, >90% cure

Question 27

Which virus, Hep B or Hep C, has a vaccine?

Answer 27

Hep B

Question 28

What is PEP?

Answer 28

Post exposure prophylaxis – x3 ARVs, HIV: up to 72 hours

Question 29

When comparing HIV, Hep C, Hep B, what is the risk of transmission?

Answer 29

HIV 1/300, HC 1/30, HB 1/3

Question 30

HIV: acute infect, prevention, outcome untreated, treatment

Answer 30

Flue like symp/nil, condoms PEP, AIDS, life-long ARV

Question 31

Hep B: acute infect, prevention, outcome untreated, treatment

Answer 31

Jaundice/abdo pain/anorexia, vaccine, cure (majority) chronic minority, nil/life-long ARV

Question 32

Hep C: acute infect, prevention, outcome untreated, treatment

Answer 32

Nil, avoidance, chronic infect (majority), 8-12 weeks ARV

Question 33

Using serology how can a past (cleared) infect be identified?

Answer 33

-ve surface Ag

+ve core Ab

+ve surface Ab

Question 34

Regarding serology how can you tell if someone has been vaccinated?

Answer 34

• ve surface Ag
• ve core Ab

+ve surface Ab