Chapter 13: Viruses

Question 1

Virion

Answer 1

Has its own

1. genetic material (eg. HIV)
2. capsid/coat
   - made of proteins
   - capsomeres
3. envelopes - protection
   - proteins
   - phospholipid
   - carbohydtrae
4. spikes
   - hemagglutination: causes aggregation of blood cells
   - 500 per virion
   - used to recognize the virius
5. neuraminidase
   - 100 per virion
   - separates the virion

Question 2

HIV

Answer 2

Human Immunodeficiency virus

• made of RNA - copies virus 1,2
• capsid
• enveloped
• gp41, gp420
• mutates very quickly, why there can’t be a vaccine for it
• enzyme reverse transcriptase
• retrovirus

RNA Single Strand - Enzyme R1 - DNA SS - Enzyme R1 - DNA SS

Question 3

Transmission of HIV

Answer 3

1. blood - transfusions, transplant organs. few - 1000 IP/mm3
2. semen and vaginal secretions. few (10) to 50 IP/mm3

Question 4

Provirus

Answer 4

1. Produces new virions
2. Latent
3. Cancer - kaposi’s sarcoma
4. Growth - occurs in Thelper or CD4 cells

Question 5

HIV Stage A

Answer 5

Th count: about 500/mm3

• CD4 is a glycoprotein found on the surface of T helper cells
• CD4 essentially = T cells
• Lymphadenopathy

Question 6

HIV Stage B

Answer 6

Th count: 200-499/mm3

• Persistent fever, diarrhea, shingles (herpes - 3 chicken pox)
• females may show pre cancerous growths on their cervix
• hairy oral leukoplakia (herpes-4)
• fungal growths (vaginal and penile)
• Lymphadenopathy

Question 7

HIV Stage C

Answer 7

Th count: < 200/mm3

• “clinical” stage
• fungus occurs in the throat
• pneumonia
• TB
• Brain degeneration

If you can stop reverse transcription, you can stop the virus

• Antiretroviral drugs
• Zidovudine (AZT)
• Laminvudine
• DDC

Question 8

Cytopathic effects

Answer 8

1. Lytic (eg. cold)
   - causes lysis of the cells, with the death of the cell they die too
2. Persistent (eg. measles)
   - can cause severe brain degeneration and can be fatal
3. Latent (eg. herpes 3 shingles, herpes 1 cold sores)
4. Cancer
   - HSV, herpes simplex virus
   - Herpes 4 converts cells into cancer cells
   a. Burkitt’s lymphoma (jaw)
   b. Nasopharyngeal cancer