Viral Replication

viral replication steps

- attachment
- entry
- synthesis
- assembly
- release

attachment

random collision between host cell and virus
- attaches to surface of host cell

what does the virus attach to?

proteins on host cell surface

entry

penetrate into cell, get into cell
- enter host cell and releases nucleocapsid

latent viruses

viruses that enter host cell but does not immediately make the host cell its slave
- delay replication
- still there just not activated
- can get activated eventually

synthesis

host cell stop doing cell work, become slaves to instructions of virus
- nucleic acid replicated & proteins made

release

new vision released from infected cell

assembly

put pieces together, build virus
- capsid, envelope
- replicated proteins & nucleic acids are assembles into nucleocapsid

direct penetration

- bind to protein on host cell membrane surface
- virion opens
- release viral genome
- genetic info in cell

direct penetration: bacterial cells

- have wall, hard to attach to
- attach to flagella and slide down to infect cell

direct penetration: human cells

- attach to membrane proteins, sugars & receptors

another form of direct penetration

injury to cell
- allows entry of virus

endocytosis

- bind to host cell membrane protein
- cell will engulf virus
- double membrane is creates around engulfed virus
- cell triggered to release nuclear capsid & genetic info into cell

endocytosis: influenza

- hemagglutinin spikes bind to protein host cells (sialic acid)
- virus taken into cell by endocytosis
- release genetic info into nucleus

sialic acid

- sugar on cytoplasmic membrane
- influenza virus binds to this
- on epithelial cells in the lungs

membrane fusion

- bind to protein/ receptor on the host cell membrane surface
- membrane fuses and become one
- genetic info in virus moves into host cell

what is specific about membrane fusion?

only works with envelope viruses