Question 1

What is an oncolytic virus? Give an example.

Accepted Answer

Viruses that prefer to infect tumor cells are called oncolytic and can be used in treating cancer. An engineered form of herpes simplex virus 1 has been developed and approved in the United States for viriotherapy as an alternative in the treatment of patients with inoperable tumors.
T-VEC is the commercial name of an engineered form of herpes simplex virus 1 that has been approved for viriotherapy.
T-VEC-infected tumor cells release fragments that attract cells of the immune system, which eventually destroy the tumor. Once the immune system is activated, it recognizes metastatic tumorous cells that might have spread throughout the body.

Question 2

Retroelements are remains of retroviral genomes in various states of decay. Which of the following are NOT retroelements?

Accepted Answer

A)  Alu sequences 
B)  HERVs 
C)  LINE 
D)  Gene transfer vectors 
E)  SINE 
A)  Alu sequences 
B)  HERVs 
C)  LINE 
D)  Gene transfer vectors 
E)  SINE D

Question 3

The genome of the influenza virus is best described as

Accepted Answer

A)  (-) strand segmented RNA. 
B)  (+) strand segmented RNA. 
C)  (-) strand single-piece RNA. 
D)  (+) strand single-piece RNA. 
E)  double-stranded RNA. 
A)  (-) strand segmented RNA. 
B)  (+) strand segmented RNA. 
C)  (-) strand single-piece RNA. 
D)  (+) strand single-piece RNA. 
E)  double-stranded RNA. A

Question 4

Sequences of endogenous retroviruses (HERVs) are remnants of retroviral infections. HERVs have accumulated over millions of years and comprise about 8% of the human genome. Briefly describe the evidence for the expression of HERV-K proteins and virus-like particles in the human embryo. What are the implications of HERV-K products interacting with embryonic factors?

Accepted Answer

Antibody staining of HERV-K capsids reve

Question 5

The lambda genome is replicated by a rolling circle mechanism. What is the end result after a round of replication?

Accepted Answer

A)  a single-stranded DNA that is immediately packaged in the phage head 
B)  two molecules resulting from a step of circle-to-circle replication 
C)  several circular molecules inserted into each other; the circles are cleaved at the cos sites and eventually relegated 
D)  a concatemer (i.e., multiple genomes joined end to tail, which are cleaved at cos sites by a terminase), producing linear double-stranded DNA prior to packaging 
E)  several Okazaki fragments that are subsequently ligated 
A)  a single-stranded DNA that is immediately packaged in the phage head 
B)  two molecules resulting from a step of circle-to-circle replication 
C)  several circular molecules inserted into each other; the circles are cleaved at the cos sites and eventually relegated 
D)  a concatemer (i.e., multiple genomes joined end to tail, which are cleaved at cos sites by a terminase), producing linear double-stranded DNA prior to packaging 
E)  several Okazaki fragments that are subsequently ligated

Question 6

What is the mechanism by which the viriotherapeutic agent T-VEC specifically kills hard-to-treat tumors?

Accepted Answer

T-VEC-infected tumor cells release fragm

Question 7

The figure below shows the structures involved in attachment of HIV to a host cell. The protein gp120 is represented by the number ________; CCR5 is indicated by ________ and CD4 by ________.

Accepted Answer

A)  1; 2; 3 
B)  2; 3; 4 
C)  3; 1; 2 
D)  4; 1; 2 
E)  5; 3; 4 
A)  1; 2; 3 
B)  2; 3; 4 
C)  3; 1; 2 
D)  4; 1; 2 
E)  5; 3; 4

Question 8

Glycosylation and packaging of the HIV env proteins occur in the

Accepted Answer

A)  endoplasmic reticulum. 
B)  nucleus. 
C)  membrane. 
D)  Golgi. 
E)  cytoplasm. 
A)  endoplasmic reticulum. 
B)  nucleus. 
C)  membrane. 
D)  Golgi. 
E)  cytoplasm.

Question 9

The HIV genome can be characterized by all of the following EXCEPT

Accepted Answer

A)  5'-"cap." 
B)  3'-poly A-"tail." 
C)  a Lys-specific tRNA. 
D)  a DNA primer. 
E)  a coated nucleoprotein. 
A)  5'-"cap." 
B)  3'-poly A-"tail." 
C)  a Lys-specific tRNA. 
D)  a DNA primer. 
E)  a coated nucleoprotein.

Question 10

Describe the several features of lentivectors. What are their molecular sources?

Accepted Answer

A lentivirus such as HIV is engineered t

Question 11

What is the cause for cloudy centers appearing in lambda plaques on an Escherichia coli confluent plate?

Accepted Answer

A)  A low multiplicity of infection prevents the appearance of large numbers of lysed cells. 
B)  Cell debris forms a physical barrier between uninfected cells and virions. 
C)  Compounds in agar or nutrient medium protect bacterial cells from infection. 
D)  A large number of infected cells become resistant to bacteriophage infection. 
E)  Some infected cells become lysogens and start growing up where the infection began. 
A)  A low multiplicity of infection prevents the appearance of large numbers of lysed cells. 
B)  Cell debris forms a physical barrier between uninfected cells and virions. 
C)  Compounds in agar or nutrient medium protect bacterial cells from infection. 
D)  A large number of infected cells become resistant to bacteriophage infection. 
E)  Some infected cells become lysogens and start growing up where the infection began.

Question 12

Use the figure below to describe the events leading to the fusion between influenza virus A and host membranes. What structures are indicated by the numbers?

Accepted Answer

Influenza virions enter the cell by endo

Question 13

The term "________" describes the mutation-caused emergence of multiple viral strains that present differing properties of replication, tissue tropism, and drug resistance within a single infected individual.

Accepted Answer

A)  hybrid species 
B)  candidatus species 
C)  quasispecies 
D)  lethal species 
E)  type species 
A)  hybrid species 
B)  candidatus species 
C)  quasispecies 
D)  lethal species 
E)  type species

Question 14

RNA synthesis of influenza virus is primed by 7-methylguanine fragments of host mRNA, obtained by

Accepted Answer

A)  telomerase activity. 
B)  the rolling-circle mechanism. 
C)  endocytosis. 
D)  exocytosis. 
E)  cap-snatching. 
A)  telomerase activity. 
B)  the rolling-circle mechanism. 
C)  endocytosis. 
D)  exocytosis. 
E)  cap-snatching.

Question 15

Control proteins Cro and CII lead to lysis or lysogeny, respectively. What environmental signal in the host contributes to regulate the amount of CII by influencing the activity of the protease HflB?

Accepted Answer

A)  Mg2+ ion concentrations 
B)  temperature 
C)  water availability 
D)  nutrient concentrations 
E)  helper phages 
A)  Mg2+ ion concentrations 
B)  temperature 
C)  water availability 
D)  nutrient concentrations 
E)  helper phages

Question 16

Which of the following is FALSE regarding the establishment of lysogeny?

Accepted Answer

A)  Lambda phage DNA integrates as a prophage in the host genome at the att site by site-specific recombination. 
B)  Rolling-circle replication generates multiple genomes in tandem, which are eventually cleaved by the enzyme terminase. 
C)  Production of the repressor CI by the integrated prophage prevents superinfection by other lambda phages. 
D)  A CI lambda repressor dimer binds to the major groove of a specific DNA sequence in the bacterial host, preventing the transcription of lytic promoters. 
E)  Once integrated in the host's DNA, gene expression from the prophage is limited to a few proteins, including the repressor C1. 
A)  Lambda phage DNA integrates as a prophage in the host genome at the att site by site-specific recombination. 
B)  Rolling-circle replication generates multiple genomes in tandem, which are eventually cleaved by the enzyme terminase. 
C)  Production of the repressor CI by the integrated prophage prevents superinfection by other lambda phages. 
D)  A CI lambda repressor dimer binds to the major groove of a specific DNA sequence in the bacterial host, preventing the transcription of lytic promoters. 
E)  Once integrated in the host's DNA, gene expression from the prophage is limited to a few proteins, including the repressor C1.

Question 17

Which are the main open reading frames (ORFs) present in all retroviruses, including HIV?

Accepted Answer

A)  vif, vpi, vpu 
B)  env, pol, gag 
C)  tat, nef, rev 
D)  vif, pol, tat 
E)  tat, nef, vpu 
A)  vif, vpi, vpu 
B)  env, pol, gag 
C)  tat, nef, rev 
D)  vif, pol, tat 
E)  tat, nef, vpu

Question 18

HIV-infected cells can fuse with neighboring cells, subsequently forming a giant multinucleate cell known as a

Accepted Answer

A)  transgene. 
B)  syncytium. 
C)  hypha. 
D)  tumor. 
E)  coenocyte. 
A)  transgene. 
B)  syncytium. 
C)  hypha. 
D)  tumor. 
E)  coenocyte.

Question 19

The lack of ________ in some people makes them resistant to HIV infection.

Accepted Answer

A)  CD4 receptors on the macrophages 
B)  CCR5 receptors on the macrophages 
C)  T4 lymphocytes 
D)  B-cell receptors 
E)  nuclear factor kappa beta in the B cells 
A)  CD4 receptors on the macrophages 
B)  CCR5 receptors on the macrophages 
C)  T4 lymphocytes 
D)  B-cell receptors 
E)  nuclear factor kappa beta in the B cells

Question 20

Endogenous retroviruses (ERVs) express viral components, including reverse transcriptase, as part of the host cell normal functions. What role do ERVs play in mouse B-cell immune response to carbohydrate antigens?

Accepted Answer

B-cell antigen receptors are antibody-li

Exam 11: Viral Molecular Biology

What is an oncolytic virus? Give an example.

Retroelements are remains of retroviral genomes in various states of decay. Which of the following are NOT retroelements?

The genome of the influenza virus is best described as

The lambda genome is replicated by a rolling circle mechanism. What is the end result after a round of replication?

What is the mechanism by which the viriotherapeutic agent T-VEC specifically kills hard-to-treat tumors?

The figure below shows the structures involved in attachment of HIV to a host cell. The protein gp120 is represented by the number ________; CCR5 is indicated by ________ and CD4 by ________.

Glycosylation and packaging of the HIV env proteins occur in the

The HIV genome can be characterized by all of the following EXCEPT

Describe the several features of lentivectors. What are their molecular sources?

What is the cause for cloudy centers appearing in lambda plaques on an Escherichia coli confluent plate?

Use the figure below to describe the events leading to the fusion between influenza virus A and host membranes. What structures are indicated by the numbers?

The term "________" describes the mutation-caused emergence of multiple viral strains that present differing properties of replication, tissue tropism, and drug resistance within a single infected individual.

RNA synthesis of influenza virus is primed by 7-methylguanine fragments of host mRNA, obtained by

Control proteins Cro and CII lead to lysis or lysogeny, respectively. What environmental signal in the host contributes to regulate the amount of CII by influencing the activity of the protease HflB?

Which of the following is FALSE regarding the establishment of lysogeny?

Which are the main open reading frames (ORFs) present in all retroviruses, including HIV?

HIV-infected cells can fuse with neighboring cells, subsequently forming a giant multinucleate cell known as a

The lack of ________ in some people makes them resistant to HIV infection.

Endogenous retroviruses (ERVs) express viral components, including reverse transcriptase, as part of the host cell normal functions. What role do ERVs play in mouse B-cell immune response to carbohydrate antigens?

Microbial Life: Origin and Discovery

Observing the Microbial Cell

Cell Structure and Function

Bacterial Culture, Growth, and Development

Environmental Influences and Control of Microbial Growth

Viruses

Genomes and Chromosomes

Transcription, Translation, and Bioinformatics

Gene Transfer, Mutations, and Genome Evolution

Molecular Regulation

Biotechniques and Synthetic Biology

Energetics and Catabolism

Electron Flow in Organotrophy, Lithotrophy, and Phototrophy

Biosynthesis

Food and Industrial Microbiology

Origins and Evolution

Bacterial Diversity

Archaeal Diversity

Eukaryotic Diversity

Microbial Ecology

Microbes in Global Elemental Cycles

Human Microbiota and Innate Immunity

The Adaptive Immune Response

Microbial Pathogenesis

Microbial Diseases

Antimicrobial Therapy

Clinical Microbiology and Epidemiology

Filters

The figure below shows the structures involved in attachment of HIV to a host cell. The protein gp120 is represented by the number ; CCR5 is indicated by and CD4 by .