chapter 18

Question 1

Immunodeficiency:

Answer 1

-any deficiency in the immune response
- may result from a defect in phagocytosis, the humoral response, or the cell-mediated response
- Combined immunodeficiencies affect both the humoral and cell-mediated immune response

Question 2

A condition resulting from a genetic or developmental defect in the immune system

Answer 2

Primary immunodeficiency

Question 3

the loss of immune function and immunodeficiency syndrome (AIDS). results from exposure to various agents

Answer 3

Secondary (acquired) immunodeficiency

Question 4

agents are microorganism that healthy individuals can harbor with no ill consequences but that cause disease in those with impaired immune function

Answer 4

Opportunistic agents

Question 5

Combined immunodeficiencies disrupt ______________ immunity

Answer 5

adaptive

Question 6

Stem from genetic defects leading to a lack of T cells in the periphery

Answer 6

Severe combined immunodeficiency (SCID)

Question 7

Screening newborn blood samples for TCR gene rearrangement products called _________________________

Answer 7

TCR excision circles

Question 8

What are the most common ways that HIV is transmitted?

Answer 8

• sex contact
• sharing of HIV- contaminated needles ( e. g., by injection drug users)
• blood transfusions using infected blood or blood- clotting factors
• accidental needlestick injuries ( healthcare workers are at risk while working with HIV- positive patients)
• congenital AIDS ( before or during birth or through breastfeeding)
• sharing of HIV- contaminated tattoo needles, razors, acupuncture needles, or ear-piercing implements.

Question 9

What is the causative agent of AIDS?

Answer 9

retrovirus HIV-1

Question 10

What is the mechanism of HIV?

Answer 10

-RT uses RNA genome to form a cDNA copy
-cDNA copy integrated into host cell chromosome, directing the rest of the viral replication cycle

Question 11

T-cell-tropic strains utilize_________ on T cells as a coreceptor

Answer 11

CXCR4

Question 12

Macrophage-tropic strains use ________as a coreceptor.

Answer 12

CCR5

Question 13

What are the four specific criteria for actual AIDS?

Answer 13

-Evidence of infection with HIV-1
-<200 CD4+ T cells/μL of blood
-Impaired/absent DTH reactions
-Occurrence of opportunistic infections

Question 14

What can make individual drugs less useful?

Answer 14

High mutation rates

Question 15

Highly active antiretroviral therapy (HAART):

Answer 15

– Combination of drugs with different mechanisms
– Reduce chances of mutations to drugs
– Very effective; can reduce viral loads below limits of detection
– NOT A CURE
– Can also be used prophylactically in high-risk groups

Question 16

Why is a vaccine for HIV/AIDs hard to produce?

Answer 16

• Virus mutates rapidly, so production of Ab not effective
• Good animal models are limited and expensive
• Dangers of testing attenuated vaccines
• Trials so far have been largely ineffective