Viral-Replication-Strategies

Ch.2, Unit II

What are the five key steps a virus must undergo to successfully infect a host cell?

1. Recognize/attach to host cell

2. Entry/uncoating of the viral genome

3. Gene expression/protein production

4. Genome replication

5. Assembly/exit from host cell

How do viruses enter host cells and uncoat after attachment?

Wil vary depending on the type of virus and the host/cell organism:

• Entry of enveloped viruses (e.g., influenza, HIV)

• Entry of non-enveloped viruses (e.g., reovirus)

• Entry of bacteriophages (e.g., T4 phage)

• Entry of plant viruses (e.g., tomato yellow leaf curl virus)

What occurs during entry of enveloped viruses? (Influenza)

Membrane fusion event between the virus and the endosomal membrane.

What occurs during entry of enveloped viruses? (HIV)

Membrane fusion between the viral membrane and the cellular membrane.

What occurs during entry of non-enveloped viruses?

During the entry of non-enveloped viruses, a change in the virus's shape creates a hole in the endosomal membrane. This hole allows the virus's outer shell or its genetic material to be released into the cell's cytoplasm.

What occurs during the replication cycle? (Entry into bacteria)

What occurs during the replication cycle? (Entry into plant cells)

What is viral uncoating?

Viral uncoating is when a virus releases its genetic material into a host cell. Different viruses use different methods, but the main goal is to get the viral genome inside the host cell so it can start making more viruses.

(iClicker Question) Bacteriophage attachment to a cellular receptor leads to injection of what into the host cell?

Genome

(iClicker Question) The influenza virus, like many enveloped RNA viruses, enters host cells via?

Endocytosis 

dsDNA Viruses

Double-stranded DNA

Most of them will make their way into the nucleus to use our machinery (not all)

ssDNA Viruses

Single-stranded DNA

Must go into the nucleus 

DsDNA Viruses using reverse transcription

Double-stranded DNA