Exam 2 Flashcards
Select any 1 of the animal viruses that we focused on that can establish latent infection in humans. Identify and describe the disease caused by the virus you selected. Include: the features of the acute infections on the host caused by the virus, explain how the latent infection is established, and the impact on the host including what happens if the virus is reactivated and exits the latent state
Herpes Varicella Zoster (HVZ)
• Initially causes acute infection resulting in the disease known as chicken pox. Characteristics of chicken pox includes itchy skin blisters, fever, upset stomach, headache, etc.
• Latent infection usually occurs prior to vaccines, but the viral DNA integrates into the genome of the host chromosome.
• Some things that cause reactivation of this virus includes hormonal fluctuations, waning immunity, emotional stress, etc. The acute infection that results from the reactivation of the virus is known as shingles. Some symptoms are a painful rash and neuropathy at epithelial sites adjacent to the cells that the virus integrated into
Antigenic drift in influenza virus involves which of the following?
A. Loss of the viral envelop which permits the virus to hide from host defenses
B. Co-infection of a host by 2 or more different influenza viruses (e.g. One originally infecting birds and one originally infecting humans) resulting in a viral gene reassortment that generates a new viral subtype
C. The elimination of a particular influenza strain because of aggressive immunization
D. Integration of influenza proviral DNA into the genome of the infected host cell resulting in a latent infection
E. Small mutations in the hemagglutinin and neurominidase genes of influenza that accumulate to generate new viral strains
E
Which of the following is a virus that belongs to a phylogenetic family whose members include viruses that cause the common cold?
- Rotavirus
- Hepatitis B virus
- HIV
- Herpes Simplex virus (HSV)
- SARS-CoV-2
SARS-CoV-2
Which viruses can potentially cause cancer?
A. All animal viruses B. All bacteriophages C. Any animal virus with an RNA genome D. Those animal viruses whose genomes (or proviral form) can integrate into the genome of the infected host cell E. Any animal virus with a DNA genome
D
Which of the viruses listed below have genomes that serve directly as mRNA so that some viral proteins are made almost immediately after the viral genome is released into the cytoplasm of the infected host cell?
- Herpes varicella (HVZ) virus (a double-stranded DNA virus)
- Poliovirus (a plus-stranded RNA virus)
- Hepatitis B virus (HBV, a reverse-transcribing DNA virus
- Influenza virus (a minus-strand RNA)
Poliovirus (a plus-stranded RNA virus)
Which of the following systems uses all the characteristics listed below to classify viruses?
• Form of the viral genome
• Process used to make viral mRNA
A. The International Committee on Viral Taxonomy (ICTV)
B. The Baltimore System
C. Both the Baltimore System and the ICTV
B
Human immunodeficiency virus (HIV) is a retrovirus. Organize the enzymes/enzymatic reactions involved in the replication of this virus’ genome into the proper chronological order
A. The proviral DNA integrates into the genome of the infected host cell
B. Viral reverse transcriptase functions as a DNA-dependent DNA polymerase generating a double-stranded DNA molecule
C. Viral reverse transcriptase functions as an RNA-dependent, DNA polymerase to generate a -DNA/+RNA hybrid molecule
D. Host RNA polymerases (a DNA-dependent RNA polymerase) is used to synthesize viral +RNA
E. Viral reverse transcriptase uses its RNase H activity to degrade viral+ RNA
C, E, B, A, D
Viruses that infect bacterial cells cannot infect animal cells
- True
- False
True
Enveloped viruses whose envelopes become removed by a disinfectant or detergent are no longer infectious
- True
- False
True
Like bacteria, most viruses can be grown in the laboratory by directly inoculating them on/into a general-purpose medium like tryptic soy agar (TSA) or nutrient broth
- True
- False
False
Which of the following most accurately describes the role of viral integrase (encoded by the viral int gene) when E. coli is infected by temperate phage lambda? Integrase is….
A. A viral polymerase needed for replication of the double-stranded DNA genome of phage lambda
B. A regulatory protein that will bind to the operator region adjacent to the cro gene blocking transcription of the cro which in turn prevents entry into the lytic cycle
C. A viral protease that will degrade the viral cro protein thereby preventing entry into the lytic cycle
D. A viral nuclease that will cut the E. coli chromosome permitting the viral DNA to integrate and establish lysogeny
D
Which of the following is the early viral protein whose function is to enhance the transcription of genes necessary for entry into the lytic cycle following infection of E. coli by temperature phage lambda?
- Cro protein
- Integrate
- cIII protetin
- cII protein
- Lambda repressor
Cro protein
In a naked virus this is the structure/component that is most likely to be directly involved in adsorption
- RNA
- Viral polymerase
- DNA
- Envelope
- Capsid
Capsid
Exocytosis and budding are mechanisms that might occur during which of the stages of viral replication listed below?
- Assembly
- Release
- Adsorption
- Penetration
- Synthesis
Release
When bacteriophages infect bacterial cells and complete the steps of synthesis and assembly, how are the assembled viral particles released from the infected host cells?
- Lysis of the host cell
- Exocytosis
- Budding through the host cell’s membrane
- Any of the above mechanisms might be used depending on the type of bacteriophage
Lysis of the host cell
Which of the following play a role in the replication of rotavirus (a double-stranded RNA virus)?
- Viral reverse transcriptase
- Host cell DNA polymerase
- Viral RNA-dependent, RNA-polymerase (RdRP)
- Host cell RNA polymerases
Viral RNA-dependent, RNA-polymerase (RdRP)
Explain what antigenic shift is, how or why it can occur in influenza virus as opposed to the other viruses we studied, and what the role antigenic shift plays in causing infections and disease
Antigenic shift is small changes that occur over time to create a new strain of the virus. These small changes or mutations result from errors made by RNA-dependent RNA-polymerase during replication. If a virus can undergo these small constant changes over time, they can allow for infection since the hosts will not have any prior immunity
