T6: TB and HIV

Question 1

Describe the structure of a HIV virion

Answer 1

Capsid containing two copies of viral mRNA and viral proteins
Encased in the lipid bilayer and a layer of viral protein
Has GP120 receptors

Question 2

What are GP120 receptors and their role

Answer 2

Glycoprotein receptors that bind to CD4 receptors

Question 3

Describe the lifecycle of HIV

Answer 3

• GP120 receptors bind to CD4 receptors on T-helper cells
• Virus envelope fuses with cell surface membrane
• Viral reverse transcriptase copies viral mRNA to DNA
• Integrase inserts this viral DNA into the host cell’s DNA
• Transcription of this DNA occurs and translation occurs at the ribosomes - producing virus proteins
• Virus proteins and envelope proteins produced are transported to membrane of cell
• Virus envelope proteins incorporated into cell membrane
• Virus particle buds off wrapped in clel membrane which forms viral envelope

Question 4

Name the 3 stages of HIV

Answer 4

Acute, chronic and AIDS

Question 5

Brief summary of acute stage of HIV

Answer 5

• antibodies may appear in blood 3-12wks
• may experience symptoms of sweats, fever and headache or NONE
• replication of virus and loss of t-helper cells initially occurs
• t-killer begin to destroy t-helper and virus replication begins to slow

Question 6

Brief summary of chronic stage of HIV

Answer 6

frequency of other infections increases and this stage may last many months or years

Question 7

Summary of AIDS phase of HIV

Answer 7

Occurs when the immune system can no longer fight the disease
Opportunistic infection may occur such as gut flora

Question 8

definition of immunocompromised

Answer 8

200 or less t-helper cells per mm3 of blood

Question 9

Describe primary infection of TB

Answer 9

Bacterium enters through respiratory tract
TB are engulfed bt macrophages
Granuloma forms in lungs which contains dead bacteria and macrophages in anaeroboic conditions
TB bacteria survive in macrophages and can supress t-cells

Question 10

Describe secondary infection of TB

Answer 10

When the immune system can no longer contain the infection within the lungs
Tb rapidly reproduce causing cavities in the lungs
Symptoms include: shortness of breath; coughing; weight loss and fever

Question 11

Why does the secondary phase occur in TB

Answer 11

old age
malnutrition
large number of bacteria
AIDS/HIV

Question 12

Name one antibiotic involved in TB treatment

Answer 12

isonizaid

Question 13

Main method of preventing TB

Answer 13

Vaccination