ViroExam 1 MultiChoice & Exams1-3 Short Answers

Question 1

🔸what is the envelope?

Answer 1

Membrane surrounding virus nucleocapsid

Question 2

🔸how do most viruses acquire envelopes?

Answer 2

By budding through a host cell membrane

Question 3

🔸which of the viruses is the biggest?

Answer 3

Poxvirus

Question 4

🔸capsid does not provide protection against what?

Answer 4

Antibody binding

Question 5

🔸Which has the largest genome of all known RNA viruses?

Answer 5

Coronavirus

Question 6

🔸replication of RNA viruses typically takes place where?

Answer 6

Cytoplasm

Question 7

🔸most alphaviruses are transmitted by?

Answer 7

Mosquitos

Question 8

🔸which flavivirus can’t be transmitted by mosquitos?

Answer 8

Hepatitis C virus

Question 9

🔸what virus uses IRES for gene translation?

Answer 9

Hepatitis A virus

Question 10

🔸Coronaviruses are not transmitted by _____.

Answer 10

Ticks

Question 11

🔸which virus virions doesn’t have projections?

Answer 11

Flavivirus

Question 12

🔸Describe the Baltimore classification system.

Answer 12

It is a classification system for viruses and their are 7 groups:

1. dsDNA
2. ssDNA
3. dsRNA
4. +ssRNA
5. -ssRNA
6. ds/ssDNA
7. ssRNA with RT

Question 13

🔅Describe five possible HIV transmission routes.

Answer 13

1. Sharing needles or other sharp objects
2. Sexual contact (semen or vaginal fluids)
3. Blood transfusion
4. Congenital (pregnant mothers passing it on to their children during birth
5. Accidental needle injection such as in the healthcare field

Question 14

🔸Describe dengue antibody dependent enhancement.

Answer 14

Antibodies are produced in response to the dengue infection but are not neutralized against other serotypes. On the 2nd time of infection, these antibodies can help the virus and can cause a more severe disease such as hemorrhagic fever or shock syndrome.

Question 15

🔹Describe the common characteristics of mononegaviruses.

Answer 15

• their genome is single, linear -RNA packaged in a helical nucleocapsid
• a virus…..IDK

Question 17

🔅 Describe the advantages of using baculoviruses expression system.

Answer 17

1. Genome can accommodate large fragments of foreign DNA.
2. Non infectious to vertebrates.
3. Can be propagated to high titers adapted for growth. (large amounts of recombinant protein)
4. Use many of the protein modification, processing, y transport.

Question 18

🔸Describe virion, viroid, and prion.

Answer 18

Prion: an infectious protein
Viroid: small circular RNA molecules; no capsid or envelope
Virion: an infectious particle

Question 19

🔹What is a tripartite leader? What are the roles of the tripartite leaders?

Answer 19

It is 3 short exons in the first 4kb of these transcripts are spliced together (in adenovirus).
Roles are: ensuring efficient transport of late mRNAs to cytoplasm.
directs efficient translation of late adenovirus proteins.

Question 20

🔹Describe the possible mechanisms by which H1N1, swine flu virus emerged.

Answer 20

The reassortment or ‘antigenic shift’ of the virus caused the pandemic of H1N1. The major change of the H (hemaglutinase) and N (neurimidase) antigens caused the reassortment of the viral genome, which can lead to new surface molecules such as H1 and N1 that changes the virus’s envelope. This causes a new viral strains that can infect animals and humans.

Question 20

🔅Describe five classes of HIV inhibitors.

Answer 20

1. CCR5 blocking inhibitors - inhibits binding of virus to host membrane.
2. RT inhibitors - inhibits RT of viral genome.
3. Fusion inhibitors - inhibits fusion of viral envelope to cell membrane
4. Integrate inhibitors - inhibits integrated provirus into host chromosome.
5. Protease inhibitor - inhibits maturation of viral proteins.

Question 21

🔅Briefly describe Poxvirus replication cycle

Answer 21

Poxvirus replicates in the cytoplasm which is unusual for a DNA virus. Virions are assembled at the plasma membrane not by budding. Has virions in 2 infectious forms: Mature Virus and Extracellular Virus. MV has 1 lipid layer y can transmit between individuals. EV has 2 lipid membranes y can spread virus from cell to cell.