SSU home

..Biology Department home

 

Virology

Home | Index | Syllabus | Schedule | Study aids | Computing | Links | Interactive

 

Spring, 2004 Lecture Outline

2/12 REPLICATION/INFECTION CYCLE


Defining replication vs. infection:

replication- making copies of new virion
infection- host cell vs. host organism

From the outside looking in:

growth curves- timing & numbers
shift in cellular processes during virus infection

Hershey-Chase experiment with T2 phage

Replication cycle:

Attachment: required for all except plant viruses [why?]
sites; cell receptors

see Table 6.1 for a list of some vertebrate receptors

attachment proteins of virus- part of capsid, envelope protein, peplomer

Penetration: [plants need direct breach of cell membrane]

1. injection of genome while capsid remains outside

2. translocation of entire virus via cell receptor

3. endocytosis of virus via coated pits- most common

4. fusion of viral envelope c membrane

uncoating- release of genome into cytoplasm [usually]

a few release into nucleus; a few don't uncoat

Replication/gene expression: eclipse phase of growth curve

replication strategy is part of classification scheme

Assembly: combining of capsid proteins, joining/entry of genome

assembly sites recognized in cells as inclusion bodies

maturation- final processing for virion to become infectious

Release: a.k.a. burst

lysis c rapid release of progeny [hence "burst"]

budding- shedding may occur over long period

exocytosis- release via vesicle fusion c cell membrane

cell-cell transmission- cell/cell contact

 

Bring CRC book to class Tuesday to play "Name That Virus"
Download ICTV Virus Key: http://www.ncbi.nlm.nih.gov/ICTV/new_virkey.html


Next week:

Taxonomy/systematics- Wagner, ch 5; NCBI & ICTV web sites; CRC, ch 2, table 1
Non-enveloped [+] strand RNA viruses- Wagner, ch 15; CRC, ch 7

 

Home | Index | Syllabus | Schedule | Study aids | Computing | Links | Interactive

 Updated 1/25/04 by thatcher@sonoma.edu