Flashcards in Chapter 26: Retroviridae, HIV, and AIDS Deck (21):
Normal cells, when growing on a plate, will form a single layer and stop dividing when they touch each other
Malignant cells lose contact inhibition and pile up
Rous sarcoma virus
Acute transforming virus - carries intact oncogene within viral genome
ONLY known acute transforming virus that is non-defective andhas full RNA genome needed for replication
Src encodes Transmembrane protein that phosphorylates tyrosine ten times the normal rate
It is a retrovirus
Linked to paralytic disease: tropical spastic paraparesis
Describe HIV structure
Sperical enveloped virion with central cylindrical nucleocapsid
Virion core: 2 identical SS RNA pieces
NC proteins bound to RNA
3 enzymes: protease, reverse transcriptase and integrase
surface glycoproteins: gp120 gp41
crucial to HIV virulence and evasion of the host immune system
Downregulates expression of both and CD4 and MHC class I
blocks the effects of APOBEC3 enzyme
break down newly synthesized viral DNA
In order for fusion and translocation of HIV across the cell membrane what must happen
CD4 binds gp 160
and coreceptor CCR5 or CXCR4 (helper T cells and Mo)
If pts fail to produce normal levels of CCR5 what happens?
appears to be resistant to HIV infection
What are the stages of HIV?
1. acute viral illness: viremia, symptoms like mononucleosis, 1 month after exposure
2. Clinical latency: 8 years, no symptoms, steady gradual destruction of CD4 T cells
3. AIDS: 2 years then death, Opportunistic infection,
High levels correlates with a greater risk of opportunistic infection
Tells you the speed of the train
*CD4 count tells you where the train currently is
Multinucleated giant cells
T-cell to T-cell fusion allows virus to pass from infected cell to uninfected cell without contacting blood and protects from antibodies
B-cells and HIV
Diminished ability to produce antibodies in response to new antigens or immunizations
Monocytes and Mo and HIV
Serve as reservoirs for HIV as it replicates, protects from immune system
Migrate across BBB carrying HIV to CNS
What malignancies do AIDS pts often suffer from?
B-cell lymphoma: EPV
Kaposi's sarcoma: HHV-8, lesions red to purple, plaques or nodules and arise on skin all over the body
What bacterial and mycobacterial infections do HIV pts often suffer from?
Mycobacterium avium-intracellulare (MAI): non tuberculous mycobacterium, smoldering
What fungal infections do AIDS pts often suffer from?
Cryptococcus neoformans: cryptococcal meningitis, fever no Kernigs
Pneumocystis jiroveci penumonia (MOST COMMON)
What is the most common opportunistic infection in the U.S among pts with AIDS?
Pneumocystis jiroveci pneumonia
What viral infections do AIDS pts often suffer from?
Herpes zoster: shingles
EBV: oral hair leukoplakia (hairlike projections arising from side of tongue), B-cell lymphoma
What protozoal infections do AIDS pts often suffer from?
Toxoplasma gondii: mass lesions in the brain
Isospora belli (#1 cause of diarrhea in AIDS pts)