Pharmacology Lecture 11_Intro to viruses

Question 1

What are the three capsid shapes for viruses

Answer 1

Icosahedral: (basically spherical)
Helical: (a the capsid interacts with the helical genome and becomes helical)
Complex: grab bag for eveything else

Question 2

What is Transformation (with respect to viral infections)

Answer 2

It is when a viral infection causes a cell to transforme into a cencerous phenotype. The only currently know example of this is Human T-cell Lukemia Virus (HTLV). Other viral infections can predispose people to cancer but also require several other factors.

Question 3

Define plus sense RNA geneome

Answer 3

This is a single strand RNA genome virus that can be directly translated by a host ribosome.

Question 4

Define Syncytia formation

Answer 4

Syncytia formation is specific to enveloped viruses. The viral envelope has glycoproteins that promote attachement to a cell membrane. When the envelope fuses with the cell membrane, the viral capsid is released into the cell and the envelope becomes part of the cell membrane. The envelope glycoproteins will then attach to a near by cell. When the replicated virus is released and infects nearby cells they will also attach to nearby cells and this can create a super cell

Question 5

What are the three main components of a virus

Answer 5

1) The genome (DNA or RNA)
2) The capsid (protein shell that protects the genome
3) (sometimes) the envelope (a lipid bilayer membrane)

Question 6

What are the 7 steps of viral replication

Answer 6

• Attachment
• Entry
• Uncoating
• Viral gene expression (Transcription & Translation)
• Viral genome replication
• Assembly
• Maturation and egress

Question 7

What two viruses often cause hyperplasia?

Answer 7

Epstein Barr virus and Papilloma virus

Question 8

Define lytic infection. give an example of a virus that causes lytic infection

Answer 8

Lytic infection is where a virus damages the host cell and causes it to lyse. This is common in upper respitory infections caused by rhinovirus

Question 9

Describe the eclipse phase of viral replication

Answer 9

As viruses are taken up by host cells, they become nonifectiouse to new cells. Thus the time period between when a virus is taken up and the when it’s progeny is released from the host cell, there is no detectable infectiouse virus. This time period is refered to as the eclipse phase.

Question 10

Define minus sense RNA geneome

Answer 10

This is a single strand RNA genome that cannot be directly translated. The virus needs a RNA polymerase to create a plus sense strand.