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Flashcards in Immunity Deck (66)
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What are the ten stages of the HIV life cyle?

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  1. Free virus
  2. Attachment & entry
  3. Penetration
  4. Reverse transcription
  5. Integration
  6. Transcription
  7. Assemby
  8. Budding
  9. Freedom
  10. Maturation


What is first step of the HIV cycle?

Free virus


What is the second phase of the HIV cycle?

Attachment and Entry

  • Virus binds to CD4 molecule (Helper T cell) on its surface


Another name for the Helper T cell?



What is the third phase in the HIV cycle?


  • Virus empties into contents into cell


What is the fourth phase in the HIV cycle?

Reverse Transcription

  • Converts RNA to DNA
  • The reverse transcriptase enzyme makes a "mirror image" of viral RNA strands to create double-stranded DNA


What is the fifth phase of the HIV cycle?


  • Viral DNA is inserted into the cell's own DNA by the integrase enzyme
  • The viruse and your cell are one


What is the sixth phase in the HIV cycle?


  • When the infected cell divides, the viral DNA is "read" and long chains of proteins are made
  • Protein synthesis into making new HIV virus


What is the seventh stage of the HIV cycle?


  • Immature virus pushes out of the cell
  • Takes some cell membrane with it
  • The protease enzyme starts processing the proteins in the newly forming virus 


What is the ninth stage of the HIV cycle?


  • Immature virus breaks free of the infected cells


What is the tenth phase in the HIV cycle?


  • The protease enzyme finished cutting HIV protein chains into individual proteins
  • These combine to form the viral core 
  • Makes a new working virus


What is an antigen?


  • Marker/ badge on the outside of a cell


How does the immune system recognize antigens?

Helper T Cells

  • Also known as CD4s 


What are the immuni-dominant antigents of influenza?

Ig H & Ig N

(ex: H1N1) 


On what part of the influenza virus are the antigens located? 

Antigens N and H are located on the surface of the viruse


What occurs during an "antigenic shift"? 

The antigens change (shift) to create a new strain


What is antigenic shift?

Antigenic shift is the process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains


What are the componets of the yearly influenza vaccine? 

Antigens H and N


What are the reasons that your friend who had the flu shot but got the flu anyway?

  1. It was a different strain of the flu that your friend wasn't immunized for
  2. Had the flu already (waited too long to get the flu shot)


What other organisms can be affected by influenza? 

  • Pigs
  • Humans
  • Birds


How does the influenza virus spread within the organims and determines productive replication of the virus? 

Via mutations and antigenic shifting of the influenza virus


What is an epidemic? 


a widespread occurrence of an infectious disease in a community at a particular time


What is a cytokine storm? 

Cytokine storm

The body overreacts to the virus and it causes it to destroy its down organs

Rambo overreaction 


How does the immune response to yearly flue differ from that of the avian flu?

Cytokine storm 


The H1N1 influenza has been the cause of four pandemics in recent history: 1918, 1957, 1968, and 2009. How is this possible to have multiple H1N1 pandemics in the same century?

  1. Antigenic shift of H1N1 virus
  2. Loss of memory T and B cells in the human body


What possible outcomes might happen if swine flu (H1N1) and avian flu (H5N1) reassorted? 

Super flu- a flu that we have not experienced yet


For a virus to infect, it must bind to the host cells at membrane receptors known as "sialic acid" receptors. These receptors differ in diferent organisms. Humans have sialic receptors know as "2,6-linked" while birds have "2,3-linked". Pigs have both receptors. Explain why Asian countries are considered the "hot zone" for new viruses to emerge. 

The "new" flu starts in Asia, due to people, birds, and pigs living in close proximity, causing an antigenic shift in the influenza virus. 


How does HIV locate the proper cells to infect? 

HIV located the Helper T cells via its antigens


How does antigens relate to proteins? 

Antigens are the markers outside of a cell

Antigens are composed of proteins

Proteins are made by genes from DNA


How does antigens relate to genes?

Antigens are the markers outside of a cell

Antigens are composed of proteins

Proteins are made by genes from DNA