HTLV1,HIV

Question 1

HTLV1 is in what virus family?

Answer 1

Retroviridae

-HIV1/2 in same family

Question 2

How is HTLV1 transmitted?

Answer 2

Parenterally
-IVDU
-Transfusion
-Sex
Transplacental

Question 3

HTLV1 infects what?

Answer 3

CD4+ T-lymphocytes

Question 4

HTLV1 Diagnosis (methods).

Answer 4

Screening
-ELISA

Confirmatory

• Western Blot or
• PCR

*Same as HIV

Question 5

Acute HTLV1 infection is typically asymptomatic, however prolonged incubation period may lead to what sequelae? (2)

Answer 5

• Tropical Spastic Paraparesis (HTLV1 ass/ myelopathy)*
• Adult T-cell Leukemia/Lymphoma (ATLL)

*Shorter incubation/may coincide w/ acute infection

Question 6

Tropical Spastic Paraparesis (HTLV1 ass/ myelopathy):

• M vs. F
• Demyelinating lesions (locations)

Answer 6

• F>M (3:1)
• Upper Thoracic
• Lower Cervical

Question 7

What is the lifetime risk of developing Adult T-cell Leukemia/Lymphoma (ATLL) if infected by HTLV1 by age 20.
-Incubation period

Answer 7

5%

-20-30 years

Question 8

Adult T-cell Leukemia/Lymphoma (ATLL) S/S:

• Physical (5)
• Serum

Answer 8

• Hepatosplenomegaly
• Jaundice
• Weight loss
• Skin rash
• Thirsty
• Hypercalcemia
• IL-2 receptor (free) HIGH

Question 9

HIV Laboratory tests - ELISA:

• Tests for what?
• Sensitivity

Answer 9

HIV1/2 antibodies to recombinant antigens/peptides
-Sensitivity >99%

*Principle method for HIV screening

Question 10

When are Anti-HIV antibodies detectable?

*p24 protein

Answer 10

within 6-8 weeks of infection (window period)

*p24 - 2-3 weeks

Question 11

What is the confirmatory test for HIV?

Answer 11

Western Blot

Question 12

The CDC has defined a positive HIV1 Western blot as what?

Answer 12

Presence of any 2 bands:

• p24
• gp41
• gp120/160

Question 13

If one or more bands are present on HIV1 Western Blot but not in combination that meets criteria for positivity, then the test is considered “indeterminate”. What is the next steps?

Answer 13

-Repeat within 6 months

• If repeatedly “indeterminate”:
• No risk factors - Negative
• Risk factors - Nucleic Acid based test is advised

Question 14

HIV Laboratory tests - CD4 count (Flow Cytometry):

• Considerations (2)
• Frequency of monitoring

Answer 14

• Diurnal variation - test at same time
• Age appropriate ref. ranges
• 6 months while disease is stable

Question 15

What is the preferred method of assessing response to antiretroviral therapy?

Answer 15

HIV RNA (viral load)

Question 16

HIV Laboratory tests - HIV Proviral DNA:

• Use/Detection
• Sensitivity/Speficity

Answer 16

Can be used to confirm diagnosis
-Result of HIV RNA reverse transcrition in to cDNA, which then integrates into host genome

Sensitivity - 95%
Specificity - 98%

*Both are low by HIV diagnosing standards

Question 17

HIV RNA vs. CD4 count:

-Correlation with long term (10 year) outcome

Answer 17

HIV RNA superior

Question 18

HIV RNA vs. CD4 count:

-Correlation with short term (6 month) outcome

Answer 18

CD4 count superior

Question 19

HIV Laboratory tests - HIV RNA (viral load, quantification)

-A change in what is considered singificant?

Answer 19

> 0.5 log

*Example: Viral load of 1,000 would be 3 log units, and a change in viral load from 1,000 to 10,000 would be expressed as a 1 log change

Question 20

Viral load (HIV RNA) is the primary variable used to determine what?

Answer 20

When to initiate Highly Active Antiretroviral Therapy (HAART)

*Viral load also determines the efficacy of the treatment

Question 21

What is the recommended test in the diagnosis of neonatal HIV infection?

Answer 21

HIV Proviral DNA (PCR testing)
-HIV RNA may be equally good

*Do NOT test umbilical cord blood