CH. 5 viruses and prions

micro bio final study guide

what is persistant viruses

viral infection that last weeks, years, lifetime

what kind of viruses cause persistent infections?

• provirus

• latent virsues

waht is latent virus

• latent viruses: dormant but can reactivate

  • ex. HSV, shingles from varicella zoster

what is provirus

• provirus: DNA incorporated into host DNA

  • ex. measles virus

what are the parts of a virus

• spikes: proteins used to attach to host cell (docking)

• capsid: protein shell that protects viral nucleic acid

• nucleic acid: DNA/RNA that carry viral genetic info

• envelope: lipid layer around some viruses, help with entry/exit

Why are antiviral drugs difficult to create

• viruses hide inside cells, which targeting is diffuclt withing harming host

what must an antiviral drug target to be effective.

• specific steps in viral life cycle

  • absorption, synthesis, assembly, release

What are the steps viruses take to invade our cells

1. absorption

2. penetration and uncoating

3. synthesis

4. assembly

5. release

Steps of Viral Invasion: what is absorption

• virus attachs to host cell via spikes

Steps of Viral Invasion: what is penetration and uncoating

• virus enters (endocytosis or fusion)

• releases nucleic acid

Steps of Viral Invasion: what is synthesis

• DNA/RNA is replicated; protein is made by enzymes/ribosomes

Steps of Viral Invasion: what is assembly

• new viral parts are put together

Steps of Viral Invasion: what is release

• 1000s of new viruses exit to infect others

what are the prion diseases

• Creutzfeldt-Jakob Disease

• variant CJD

• Bovine Spongi

what is Creutzfeldt-Jakob Disease

• genetic/spontanious

• rapid brain degeneration

  • fatal within 1 year

what is variant CJD

• human infection caused by eating contaminated beef

what is bovine spongiform encephalopathy

• mad cow disease

• prion diseases in cattle

• can spread to human (variant CJD)

what is oncogenic virsues (oncoviruses)

• viruses that cause cancer (13% of cancers)

what are the examples of common oncoviruses (oncogenic viruses)

• liver cancer→ hepatits B

• cervical cancer→ papillomavirus

• burkett’s lymphoma→ epstein-barr virus

• lymphoma/leukemia→ human t-lymphotrophic virus

what is antibiotics and antivirals

• antibiotics: kill bacteria (targets enzymes and cell wall)

• antiviral: target viral life cycles (harder since viruses use host machinery)

what is bacteriophage

• viruses that infect bacteria

• important: used in research and can alter bacterial virlence

what is lytic cycle and lysogenic cycle

• lytic cycle: virus replicates → bacterial cell bursts (lysis)

• lysogenic cycle: viral DNA integrates into bacetrail DNA (prophage), can later switch to lytic

what is temperate phages and why is it important in healthcare

• can do both lytic and lysogenic cycles

• healthcare role: lysogeny can make bacteria more harmful

what are the methods and reason to culturing viruses

• methods: live animals, bird embryos, cell/tissue cultures

• reason: viruses need living cells to replicate