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12 terms

Why is AIDS so lethal?

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HIV
human immunodeficiency virus; retrovirus that causes immune system failure and debilitation-spread through direct contact with bodily fluids; specifically attacks T cells
AIDS
acquired immune deficiency syndrome; disease of the immune system transmitted through blood products especially by sexual contact or contaminated needles; caused by HIV; last stage of HIV infection; may take 15 years for HIV to progress to AIDS; T cell count becomes less than 200 per micro-liter of blood; depressed immune system can no longer fight infections
Retrovirus
type of RNA virus that reproduces by transcribing itself into DNA using reverse transcriptase-resultant DNA inserts itself into a cell's DNA and is reproduced by the cell; contains only RNA; makes DNA in the eukaryotic cell
T-cell
small lymphocyte developed in thymus; orchestrates immune system's response to infected or malignant cells; originate in bone marrow and thymus gland; produce cellular immunity by attacking infected cells
Antigen
active component of a vaccine which stimulates the body to produce antibodies which fight off disease; stimulate immune response in body; any foreign substance that causes an immune system response
Reverse transcriptase
DNA polymerase enzyme that catalyzes the process of reverse transcription (formation of DNA using RNA as a template)
immune system
function is to find and kill harmful organisms, and take up foreign objects
steps to recognizing foreign
1) antigen presenting cell ingests virus
2) APC presents viral fragments as antigens on its surface
3) helper T cells bind to APC as they recognize antigens
4) binding activates T cells, which causes production of more T and B cells
what is a virus?
a hijacker; parasite like particle containing proteins and nucleic acids that uses host's DNA and cellular machinery to reproduce
How does HIV adversely affect the T cell immune system?
1) large numbers of viruses in T cells drain cells of nutrients and energy
2) new T cells infected by large number of viruses=weakened immune system
3) APCs less effective in stimulating T cell production
why is AIDS lethal
1) attacks helper T cells (critical to immune system)
2) single stranded RNA and reverse transcriptase mutate easily so virus is difficult to treat
3) HIV remains dormant in T cells for years
4) weakened immune system=other viral, bacterial, and fungal infections
HIV came from
chimpanzees