Blood Borne Viruses

Question 1

What are the three main blood bourne viruses?

Answer 1

Hepatitis B, Hepatitis C, and HIV

Question 2

What type of virus is HBV?

Answer 2

Hepatitis B virus is a DNA virus from the family hepdnavirus (‘hep’ ‘dna’)

Question 3

What type of virus is HCV?

Answer 3

Hepatitis C virus is an RNA virus, from the family flavivirus

Question 4

What type of virus is HIV?

Answer 4

Retrovirus and is in the lentivirus sumfamily

Question 5

What morphological feature do HBC, HCV, and HIV have in common?

Answer 5

All are enveloped viruses with a lipid outer surface (do not survive well in the environment or stresses such as desiccation)

Question 6

What are the three methods of transmission for HBV, HCV, and HIV?

Answer 6

1. Penetrative intercourse
2. Contaminated blood from needles
3. Vertical (including breast feeding)

NB all 3 viruses can transmit by any of these routes, lots of local variation in epidemiology

Question 7

What is principal mode of transmission for HIV?

Answer 7

Sexual intercourse

Question 8

What is principal mode of transmission for HCV?

Answer 8

Contaminated blood especially IV drug use

Question 9

What is principal mode of transmission for HBV?

Answer 9

Vertical including breastfeeding

Question 10

What blood component is tested for a BBV?

Answer 10

Serum, therefore send a clotted sample to the virology lab

Question 11

What can the virology lab test for in a suspected BBV? (4)

Answer 11

Type of infection

Past or current
Acute or chronic

How much virus is circulating (infectivity)

Question 12

What are theranostics?

Answer 12

Tests specifically done to guide treatment (monitor response to treatment, or drug resistance, or can look at genotype of hep C)

Question 13

Which cells are damaged by HBV?

Answer 13

Hepatocytes (damage done by immune reaction not the virus)

ie if someone is immunosuppressed they will not have disease

Question 14

What is the incubation period of HBV?

Answer 14

6 weeks to 6 months

Question 15

Initial symptoms of HBV

Answer 15

Nonspecific fever and malaise (only half of acute infections cause symptoms)

Question 16

Long term effects of chronic HBV infection?

Answer 16

Chronic active hepatitis
Cirrhosis
Hepatocellular carcinoma

Question 17

What is HBsAg? What is it used for?

Answer 17

Hepatitis B surface antigen, used as diagnostic test for the virus as it is grossly over-produced

Question 18

What is HBeAg?

Answer 18

E antigen is a soluble form of the core antigen of hepatitis B, the part of the virus that is inside the
surface antigen coat. And e antigen is important because it has a tolerogen effect

Question 19

What is the toleragen effect of HBeAg?

Answer 19

The E antigen is a soluble form of the HBV core antigen

It can cross the placenta, causing teh foetus to recognise the e antigen as SELF.

Results in a clonal deletion of lymphocytes that recognise this antigen

Therefore, removes immune response to HBV and the baby gets a chronic infection

Question 20

Chance of HBV being transmitted to baby if mother is +ve for HBsAg and not HBeAg?

Answer 20

<10%

Question 21

Chance of HBV being transmitted to baby if mother is +ve for HBsAg AND HBeAg?

Answer 21

70-90% due to toleragen effect

Question 22

What does HBsAg indicate?

Answer 22

Current infection

Question 23

What does HB core antibody (IgG) indicate?

Answer 23

Past or present infection

if you’ve had Hep B, you’ll ALWAYS have IgG

Question 24

What does HB core antigen (IgM) indicate

Answer 24

Infection in the past 6 months. Disappears after 6 months.

Question 25

What does HB e antigen indicate?

Answer 25

HIGH INFECTIVITY and high grade infection.

Question 26

What does anti-HbsAg indicate?

Answer 26

Immunity to infection (>10 MIU) either naturally or via vaccine

Question 27

What does HBV DNA (quantitative) indicate?

Answer 27

Load test that determines response to treatment.

Question 28

Difference between e antigen positive and e antigen negative infection?

Answer 28

e positive: very infectious and high grade, likely to develop chronic active hepatitis and HCC e negative: low grade infection and low risk of transmission, not likely to develop symptoms. WILL MOST LIKELY HAVE e ANTIBODY PRESENT.

Question 29

What vaccine is used for HBV?

Answer 29

Genetically modifed vaccine Uses recombinent portein expressed in yeast and is the surface antigen protein

Question 30

What groups are targeted for HBV vaccine in UK?

Answer 30

Neonates with HBV positive mums Healthcare workers Dialysis patients Contacts of HBV cases

Question 31

What treatment options are there for HBV? (3)

Answer 31

Lamivudine (aim is suppression of the virus not cure) Interferon (aim is cure of high grade infection) Liver transplant

Question 32

What are the thernostic tests for HBV?

Answer 32

Lamivudine resistence Viral load (HBV DNA)

Question 33

What cells are damaged by HCV?

Answer 33

Hepatocytes by BOTH direct viral effects and immune reaction

Question 34

How many genotypes does HCV have? Which ones are hard and easy to treat?

Answer 34

6 genotypes Genotype 1 common in NI, poor response to treatment Genotype 3, easier to treat

Question 35

What are the symptoms of HCV in acute phase?

Answer 35

Asymptomatic (only 10% get symptoms in acute stage)

Question 36

How many HCV cases become chronic?

Answer 36

70%!!

Question 37

Health effects of chronic HCV

Answer 37

50% chronic active hepatitis 20% cirrhosis (decades after infection) Around 2% a year get HCC

Question 38

What does the HCV antibody indicate?

Answer 38

Past or present infection

Question 39

What does HCV RNA (by PCR) indicate?

Answer 39

CURRENT infection

Question 40

What does the HCV genotype marker indicate?

Answer 40

Guides treatment duration Type 1=12 months Type 3=6 months

Question 41

What does it mean if patient is HCV antibody positive but HCV PCR negative?

Answer 41

Past infection

Question 42

What does it mean if patient is HCV antibody positive and HCV PCR

Answer 42

Current infection

Question 43

Treatments for HCV? (3)

Answer 43

Ribavirin (aim is cure) Interferon (aim is cure) Transplant (but it recurs in nearly 100% of cases)

Question 44

What virus is treated with Ribavirn?

Answer 44

HCV

Question 45

What virus is treated with Lamivudine?

Answer 45

HBV

Question 46

What can theronostic assays be used for in HCV?

Answer 46

Genotype detection to guide treatment length HCV RNA detection by PCR to guide response to treamtment

Question 47

Which cells are infected by HIV?

Answer 47

Retrovirus which affects immune cells: ``` CD4 lymphocytes (T helpers) Macrophages ```

Question 48

Two main subtypes of HIV?

Answer 48

HIV1 (most cases) and HIV2

Question 49

How many cases of HIV in NI?

Answer 49

400 at the RVH 80 new cases a year

Question 50

What two diseases are caused by HIV?

Answer 50

Primary HIV infection AIDS

Question 51

How long does it take to see a primary HIV infection post exposure?

Answer 51

10-25 days

Question 52

Symptoms of primary HIV infection?

Answer 52

Glandular fever, lymphadenopathy, rash

Question 53

Opportunistic infections in AIDS? (9)

Answer 53

``` Retinitis Encephalopathy Lymphoma TB CNS infection Bloody diarrhoea Oesophageal infection Pneumonia Meningitis ```

Question 54

What opportunistic infection is caused by JC polyvirus?

Answer 54

Encephalopathy

Question 55

What opportunistic infection is caused by EBV?

Answer 55

Lymphoma

Question 56

What opportunistic infection is caused by Mycobacteria?

Answer 56

TB

Question 57

What opportunistic infection is caused by Toxoplasma?

Answer 57

CNS infection

Question 58

What opportunistic infection is caused by Cryptosporidia? (protozoa)

Answer 58

Bloody diarrhoea

Question 59

What opportunistic infection is caused by Candida?

Answer 59

Oesophageal infection

Question 60

What opportunistic infection is caused by pneumocystis? (fungi)

Answer 60

Pneumonia

Question 61

What opportunistic infection is caused by Cryptococcus? (fungi)

Answer 61

Meningitis

Question 62

What is the key test for HIV?

Answer 62

HIV antibody test

Question 63

What approach is used for HIV testing?

Answer 63

4 assay approach to reduce risk of false positive

Question 64

Therapy for HIV?

Answer 64

Anti-retroviral therapy (ART) Aim is suppression not cure

Question 65

What 3 drug classes are used together to treat HIV?

Answer 65

- Nucleoside reverse transcriptase inhibitors - Non-nucleoside reverse transcriptase inhibitors - Protease inhibitors

Question 66

How can vertical HIV transmission be prevented? (3)

Answer 66

C-section Anti retroviral therapy to mother and baby Avoid breast feeding Reduces transmission from 16% to 1%

Question 67

3 theranostic assays used for HIV?

Answer 67

Viral load (response to treatment) CD4 lymphocyte count (response to treatment) Mutational analysis for drug resistance (sequencing viral genome)

Question 68

Which BBVs have vaccine?

Answer 68

HBV only

Question 69

Which BBVS have curative treatment?

Answer 69

HBV and HCV

Question 70

Which BBVs have suppressive treatments?

Answer 70

HBV and HIV For HCV, aim is cure

Question 71

Post exposure prophylaxis for HBV?

Answer 71

Vaccine and IgG

Question 72

Post exposure prophylaxis for HIV?

Answer 72

ART drugs for 6 weeks

Question 73

Post-exposure prophylaxis for HCV?

Answer 73

None

Question 74

What is the window period in virus diagnostic testing?

Answer 74

Period in which patient is infected but no antibodies have developed yet- risk of false negative