Virus Replication (RNA and DNA)

Question 1

3 Mechanisms for Viral Internalization

Answer 1

Direct penetration (viropexis)
Fusion at PM (can cause syncitium formation)
Receptor-mediated endocytosis

Question 2

3 Mechanisms of Uncoating

Answer 2

Initiated by attachment to receptor (like maybe at nuclear membrane)
Promoted by acidic environment or proteases in endosomes
Enveloped viruses uncoat on fusion w/ cell membranes

Question 3

2 Phases and 2 Periods of Virus Growth Curve

Answer 3

Early Phase - genomic replication going on
Late Phase - after early phase until virus release
Eclipse Period - up until virus assembly
Latent Period - up until virus release

Question 4

5 Positive Strand RNA Viruses

Answer 4

Picorna, Toga, Flavi, Calici, and Coronaviruses

Question 5

3 Segmented -Strand RNA Viruses

Answer 5

Orthomyxo, Bunya, and Arenaviruses

Question 6

3 Nonsegmented -Strand Viruses

Answer 6

Paramyxo, rhabdo, and filoviruses

Question 7

2 Ambisense -Strand Viruses

Answer 7

Arena and some Bunyaviruses.

Question 8

Important requirement for - Strand and Double Stranded Viruses

Answer 8

Because must use - strand as template for mRNA, need to carry RNA dep RNA pol

Question 9

2 Double Stranded RNA Viruses

Answer 9

Reo and rotaviruses

Question 10

3 Viral Mechs to Enhance Translation of Own Genomes (& Families that do it)

Answer 10

Internal ribosoe entry site (IRES): Picorna and flaviviruses
Cleavage of Cap binding protein: Picornaviruses
Cleavage of cellular mRNA: Orthomyxoviruses

Question 11

Naked virus assembly and exit

Answer 11

Assembled as capsid and then packaged. Exits via lysis

Question 12

Enveloped virus assembly and exit

Answer 12

Matrix protein promotes interaction of viral nucleocapsid with the viral glycoprotein modified membranes for assembly, and then release by budding or exocytosis there to get the envelope

Question 13

Parvovirus Notable Feature

Answer 13

Smallest DNA virus (and thus most dependent)

Question 14

Parvovirus Notable Genome Feature

Answer 14

Inverted repeats on end serve as primers, can flip to form + and - strands.

Question 15

Papovirus Notable Genome Feature

Answer 15

Read in one direction it has early T (transformation) genes to encourage cell growth and in the other it has late VP (structural) genes

Question 16

Adenovirus Early Genes

Answer 16

Transactivator proteins E1A and E1B for cell growth and transformation

Question 17

Adenovirus 3 Life Cycles

Answer 17

Latent - Viral genome remains in the nucleus
Lytic - full cycle
Oncogenic - changes growth regulation

Question 18

Immediate Early Genes

Answer 18

In herpes virus, code for DNA binding prots to regulate gene transcription

Question 19

Herpesvirus Early Genes

Answer 19

DNA Pol and dNTP synth enzymes like viral thymidine kinase, a target for antivirals

Question 20

4 Herpesviruses with Inverted Repeats (can recomb)

Answer 20

VZV, HSV1&2, CMV

Question 21

2 Herpesviruses with Direct Repeats

Answer 21

EBV and HHV6

Question 22

Poxviruses Unique Factor

Answer 22

All replication events take place in cytoplasm. DNA rep occurs in inclusions

Question 23

Hepadnavirus Notable Genomic Features

Answer 23

Has 3200 bp partial dsDNA circle which completes upon entering the cell to 3500bp. This starts at different points to encode overlapping different 5’ mRNAs that share 3’ end. It encodes RT and makes DNA from the large mRNA.