Ch. 21.2 Virus Infections and Hosts

What are viruses?

A parasite that must live inside cells to reproduce

What must a virus do before entering a host cell?

Recognize and attach to a specific living cell

What happens after a virus penetrates a host cell?

It copies its genome and manufactures its own proteins

3What must newly produced viruses eventually do?

Escape the host cell so they can infect other cells

Can viruses infect every species?

No. Viruses can infect only certain species of hosts

Can a virus infect every cell within a host?

No. Viruses can target only certain cells within a host

What are permissive cells?

Specific host cells that a virus can occupy and use to replicate

What determines which cells a virus can attach to?

The presence of a specific viral receptor on the host cell surface

What is a viral receptor?

A specific surface molecule on a host that a virus must reorganize and attach to

Why is a viral receptor important?

A virus requires the appropriate receptor to attach to a host cell

What is the main molecular basis for viral host-cell specificity?

The presence or absence of a specific viral receptor on the host cel

What are two additional factors that can determine which cells a virus infects?

Differences in cellular metabolism and host-cell immune responses

Why can differences in immune responses affect viral infection?

Difference cells have difference gene expression which can affect their immune responses

What does “host specificity” mean?

A virus can infect only certain species and certain cells within those speciesand its ability to attach to specific receptors on those cells.

What determines whether a virus can successfully infect a particular cell?

The cell must be permissive, have the correct viral receptor, and have cellular conditions that allow the virus to replicate