Viral Multiplication

Question 1

Viral Multiplication

Answer 1

*Viruses are obligate intracellular parasites
*Host range depends upon if a virus can 1) enter a cell, 2) find appropriate cellular machinery, and 3) exit the cell
*Virus infections of cells that yield new infectious viruses are called productive
*Non-productive virus infections occur when the viral genetic material persists in a cell (latent state), but no infectious virus is formed (no clue how many of these a there are)
*Some non-productive infections can lead to oncogenic transformation of cells

Question 2

Phases of Viral Multiplication

Answer 2

*The phases of viral multiplication are typically called: 1) attachment, 2) penetration, 3) uncoating, 4) virus component synthesis, 5) assembly, and 6) release
*The synthesis of viral proteins and viral effects on host macromolecular synthesis often result in morphological changes to the host cell collectively known as cytopathic effects (CPE), ex., cell rounding, cell fusion, etc.
*Antivirals inhibit some step in the viral multiplication process

• WHy do influenza cells only affect resp tract? B/c virus only attaches and is taken up to/by resp cells*
• Herpes - cell fusion. membranes of cells touching one receiving viral protein in membrane will all take up the protein and become infected*

Question 3

General ways of virus multiplication cycle

Answer 3

pic

Question 4

Ways of mult ctd.

Answer 4

ATTACHMENT

pic 2

Question 5

ways of mult ctd, ctd

Answer 5

PENETRATION OF VIRUS
pic

Question 6

ways of mult ctd, ctd, ctd

Answer 6

Release

Pic

Answer 9

RNA viruses can be transcribed in cytosol. 2 exceptions: AIDS and influenza replicate in nucleus cuz need enzyme to do so.

Chart - don’t memorize

Question 10

Viroporins

Answer 10

*They are small, hydrophobic virus-encoded proteins that oligomerize at host cell membranes where they are involved in enveloped virus budding and non-enveloped virus cellular lysis.
*They have several cytopathogenic effects on the cell including the formation of hydophilic pores and alterations of calcium and hydrogen gradients.

…Nake viruses lyse cells, enveloped viruses bud out of cell

Question 11

Still can have severe affects from enveloped viruses that don’t lyse cell

Answer 11

add pic

Question 12

MATURATION AND BUDDING OF ENVELOPED VIRION

Answer 12

viral protein spikes placed in host membrane. Cell dosn’t lyse, but modified cell membrane is now foreign to body and immune system kills it. Enough of this –> disease.

Question 13

Viral Cell Life Cycle (Slide 21 sequence)

Answer 13

penetration, uncoating, infiltrate host functions (replication, translation), assembly (maturation), release, infect other cells

Question 14

One step growth cycle

Answer 14

Monitor from cell culture virions produced over time. 10 viruses put in each cell. Eclipse period = no new virions made yet. B/w end of eclipse and beginning of latent, virons are being crx in original host cell. At end of Latent stage, new virons are released…

Shorter cycle in rapidly dividing cells. Body can better control viruses with longer latent period than those with shorter ones.

Question 15

One growth step

Answer 15

Early proteins made are for crx of mRNA/DNA. Late proteins made are for capsid, etc.