Pirates of host cell functions

Obligate intracellular parasites

no ribosomes, membranes or organelles

requires electron mircroscope

have either DNA or RNA

some have lipid envelope

protein coat, capsid, is composed of capsomere subunits

asymptomatic

respiratory, GI, skin

acute or persistent

rapid onset, short duration

virus is eradicated by host defenses

lasts years

balanced pathogenicity

infected carriers can transmit

latent, chronic, slow

small pox

herpes simplex

varicella-zoster (chicken pox, shingles)

epstein-barr (infectious mononucleosis)

hepatitis B

HPV

poliovirus

influenza

Hepatitis A and C

rhinoviruses (common cold)

coronaviruses (colds, SARS)

human immunodeficiency virus (HIV)

host cell becomes a plant for manufacture of new viruses

infection of a host cell with one virus can result in the release of thousands of viruses within a period of hours or days

multiplication of animal viruses:

stages in "life" cycle

1. attachment

2. penetration/entry

3. targeting replication site

4. uncoating

5. biosynthesis of viral components

6. maturation/assembly

7. release from cell

8. spreading and shedding

9. transmission to new host

virus multiplies and produces lots of virus

often kills/lyses host cell

virus doesn't cause lysis/death of host cell

can replicate as a plasmid or viral DNA becomes a part of the chromosome = provirus

on the surface

specifically bind to molecules in environment

presence varies with tissue

endocytosis or fusion

fusion: viral envolope fuses with the animal cell plasma membrane

replication of the viral genome

production of viral proteins