HIV Lab Testing

Question 1

How many HIV viruses are there?

Answer 1

HIV 1 and HIV 2

distinct viruses

Question 2

How many HIV/AIDS patients are present in sub-saharan africa compared to the rest of the world?

Answer 2

2/3 of total HIV/AIDS cases

Question 3

What is the predominant HIV virus worldwide?

Answer 3

HIV 1

Question 4

What enzyme do retroviruses use to convert RNA to DNA?

Answer 4

Reverse transcriptase

Question 5

What group of retroviruses does HIV belong?

Answer 5

Lentiviruses

Question 6

What enzyme does HIV use to integrate its DNA with that of the host cell?

Answer 6

Integrase

Question 7

Name the 4 groups of HIV 1

Which group is responsible for the global HIV epidemic?

Answer 7

Group M
Group N
Group O
Group P

HIV 1 Group M is the strain responsible

Question 8

How many subtypes of HIV 1 Group M are there?

Why are these subtypes important?

Answer 8

10

Different treatment for different subtypes

Question 9

What lab tests can you use to diagnose HIV?

Answer 9

Antigen/ Antibody tests

4th generation ELISA assays are the big ones
-Allow simultaneous detection of antibody and antigen

Question 10

What lab tests can you use to manage HIV infection?

Answer 10

Viral Load
HIV resistance testing
Subtype determination
Tropism testing
Drug levels

Question 11

What do we mean by the diagnostic window period?

Why is this important?

Answer 11

Time during which markers of infection are not detectable

Testing during this period can result in false negatives

(Varies between individuals)

Question 12

What is Viral load testing used for?

Answer 12

Used to monitor the effectiveness of HIV treatment

Used for diagnoses in presence of maternal antibody

Question 13

What is important to remember about viral load and transmission?

Answer 13

Can still transmit with an undetectable viral load

Question 14

What does HIV resistance testing involve?

Very basic terms

Answer 14

Sequencing of the polymerase and protease genes

Identification of specific mutations that confer resistance to antiretroviral drugs

Question 15

What is HIV resistance Testing used for?

4 points

Answer 15

Baseline at diagnosis

Suboptimal treatment response

Treatment failing

Want to change treatment for another reason

Question 16

What is tropism testing?

What does it do and why do we do it?

Answer 16

Which co-receptor does the virus use to enter CD4 cells, required before using a CCR5 antagonist

Question 17

Why might we test drug levels in a HIV patient?

Answer 17

Compliance

Question 18

When will a patient have to inform work of their HIV diagnosis?

Answer 18

Only if they require you to have a HIV test

(May need a HIV test to work abroad)

(If involved in healthcare will need to avoid exposure prone procedures (EPPs))

Question 19

How do you monitor HIV infection?

Answer 19

CD4 lymphocyte count

HIV viral load

Clinical features