• crushed up diseased leaf
• put juice through a pore filter
• took "clean" juice and put on healthy leaf
• healthy leaf turned to diseased leaf

• they were small (filterable agents)
• would not grow like bacteria (on a petri dish)

• crystallized a virus and studied its chemical structure
• determined it was mostly proteins
• could stimulate fever and illness
• (can be passed from person to person)

• Common colds
• influenza
• measles
• mumps
• small pox
• chicken pox
• shingles
• mononucleosis
• herpes simplex
• hepatitis A, B, C, D, E
• polio
• HIV/AIDS
• some cancers

• Cell Cultures (or tissue cultures)
• Electron Microscope

they must be grown inside a living cell

cannot functions outside the safety of the host cell

• plaques to form
• also referred to as "cytopathic effects" or CPE's
• after a while, viruses will need to move to new cells to keep growing

1. primary cell lines
2. diploid cell lines
3. continuous cell lines
4. bacterial cell lines

• mostly derived from animal organs
• Ex. kidney, pituitary, bone

• Originally derived from human fetuses
• Two of them exist
  • WI38 - developed in 1962 from lung tissue of a female
  • MRC5 - developed in 1966 from lung tissue of a male

• derived from tumor (cancer) cells
• Ex. HeLa = from Henrietta Lacks

• bacteria may be used to grow viruses instead of animal cells
• Ex. viruses grown in bacteria are called phages

• Scanning Electron Microscope
• Transmission Electron Microscope

• contain "usable" DNA & RNA
• possess ability to reproduce (replicate)

• possess a simple, cellular structure
• no metabolism of its own (an inert particle)

• all viruses must have this
• contain genetic material that has DNA or RNA ( one or the other, not both)
• called the capsid

• outer covering 
• some but not all
• consists of a protein/lipid bilayer
• get from exiting a host cell
• aids in getting into another host cell

• small protein projections
• some not all

• spikes attach to host cell
• envelope fuses with host cell membrane
• virus is now inside host cell

• H spikes
• N spikes

spikes on surface of a virus particle change enough that our antibodies no longer "recognize" spikes

now susceptible new "strain" of virus - RNA virus

• Helical
• Polyhedral
• Spherical
• Complex

• Lytic Cycle
• Lysogenic Cycle

• virus "hijacks" host cell, causing replication of infecting virus
• host cell fills with particles
• cell "bursts" (lyses)
• particles sent out to infect neighboring cells
• relatively "immediate" death of cell

• virus introduced to host cell
• incorporates itself into host DNA
• DNA replication results in virus replication
• virus stays dormant during this time
• when conditions are best, virus reactivates
• ends similar to lytic cycle
• results in a delayed death

1. Attachment
2. Penetration and Uncoating
3. Transcription
4. Biosynthesis and Assembly
5. Release

• virus binds to receptors on surface of host cell
• lock & key from spikes and receptors on cell

• virus penetrates membrane shortly after attachment
• most often capsid and genome penetrate cell as envelope "fuses" with membrane
• uncoating is next, where viral genome separates for the capsid

• virus genome stimulates cell to produce enzymes for particle production
• enzymes are called early proteins that act as the virus-making machinery

• copies of genome and capsid are made from early proteins using cell's materials
• these new components are called late proteins that will become particles themselves

• new viruses leave cell
  • budding - enveloped virus exits this way
  • bursting - nonenveloped viruses exit this way

1. attachment
2. penetration and uncoating
3. provirus
4. transcription
5. biosynthesis
6. release

• virus binds to receptors on surface of host cell
• lock & key from spikes and receptors on cell

• virus penetrates membrane shortly after attachment
• most often capsid and genome penetrate cell as envelope "fuses" with membrane
• uncoating is next, where viral genome separates for the capsid

• extra stage only for this cycle
• viral DNA integrates itself into host cell DNA
• remains dormant for a time

• virus genome stimulates cell to produce enzymes for particle production
• enzymes are called early proteins that act as the virus-making machinery

• copies of genome and capsid are made from early proteins using cell's materials
• these new components are called late proteins that will become particles themselves

• new viruses leave cell
  • budding - enveloped virus exits this way
  • bursting - nonenveloped viruses exit this way

• rapid onset of symptoms
• last for relatively short period
• primarily caused by lytic cycle
• ex.
  • colds
  • influenza
  • measles
  • norovirus

• slower onset of symptoms
• lasts for longer periods of time, sometimes years
• primarily caused by slow lytic cycle
• ex.
  • hepatitis B, C, D
  • chronic mononeucleosis

• similar to chronic viral, except symptoms may be dormant at times
• sometimes no symptoms present, few antibodies in the blood, no detectable virus
• caused by the lysogenic cycle
• activation can occur from:
  • stress
  • other illness
  • UV light
• Ex
  • herpes simplex
  • varicella (chicken pox)
  • varicella zoster (shingles)
  • HIV/AIDS

polykaryote

lesion