exam 2 study guice mcb 2
13) The varicella-zoster virus is? and causes?
(HHV-3) chicken pox
When developing drugs, what is selective toxicity and why is it important?
- Ability of drugs to kill pathogens but leave host cells unharmed
What is a concern when vaccines are made from virions purified from fertilized chicken eggs?
- Allergies
Several neurodegenerative diseases have been associated with misfolded proteins in the brain but are not considered spongiform encephalopathies. List three of them.
- Alzheimer's, Parkinson's, and ALS
List three general ways that viruses can be grown in the laboratory.
- Amniotic cavity injection - Allantoic cavity injection - Yolk sac injection
Define host range.
collection of species a virus can infect
A nucleoside analog called ...... blocks DNA replication in cells infected with HHV-1, HHV-2, or varicella-zoster virus (HHV-3).
compound acyclovir
a pathogen is
disease-causing microbes that must invade living cells and hijack their biochemical and cellular tools to replicate.
In bacteriophage, ...... kills the host cell when new phage is released.
lytic replication
19) The enzyme reverse transcriptase
makes DNA from an RNA template.
Viruses are called
obligatory parasites.
Viruses that cause persistent infections and are often associated with cancer are called ...... viruses.
oncogenic
a .... is the highest taxon for viruses
phylum
A technique called ....... amplifies specific regions of a genetic material.
polymerase chain reaction (abbreviated to PCR)
During lysogenic replication of a temperate bacteriophage, a ....... is formed when the phage genome is incorporated into the host cell's genome.
prophage
Certain animal viruses that cause chronic infections incorporate their genome into the host cell's genome to form a ........
provirus.
Any step in the viral ...... pathway can be potential drug targets.
replication
What's a halogen?
salt
HHV-3 or varicella zoster virus can reemerge and cause?
shingles
Viruses are
small, acellular infectious agents that are considered nonliving.
Prions cause a class of diseases called .......
spongiform encephalopathies.
Which of the following viral genomes is immediately ready for translation after the virus gains entry into the cell?
ssRNA+
16) In general, viral genomes can either be RNA or DNA based, but usually not both. t/f
true Note: there are some rare exceptions
23) The influenza virus undergoes processes called antigenic drift and antigen shift. Define these two processes and describe the outcome of each using the example of influenza.
- Antigenic drift: minor changes in influenza virus due to gene mutations, new strains undetected. - Antigen shift: major mutations, i.e. influenza jumping species
Why are diseases caused by prions called spongiform diseases?
- As the brain tissue deteriorates, spongy holes are left in the tissue.
List the five steps of lytic replication in the order they occur, and briefly describe what occurs during each step.
- Attachment - Penetration - Replication - Assembly - Release
3) What is a virus that infects a bacterium called?
- Bacteriophage
5) What is the medical importance of phage conversion?
- Because of prophage's ability to confer new pathogenic properties to bacterial cells
11) Where does an enveloped virus obtain its envelope?
- By budding from the host and taking a portion of the cell membrane with them
Define persistent infection.
- Chronic infections caused by persistent viruses
Define plaque.
- Clear zone on growing plate of bacteria
25) How are prions eliminated?
- Combination of chemical treatments and increased temperature and pressure during autoclaving
What type of immune assay adheres an antigen or antibody to a surface and usually changes color if binding occurs?
- ELISA assay
What does the RT-PCR test detect? What does the antigen test detect? Which test is more sensitive?
- Genetic material of SARS - SARS proteins - RT-PCR tests
Name two spongiform disease that are caused when a child inherits a parental gene that encodes a mutated form of the prion protein.
- Gerstmann-Sträussler-Scheinker syndrome and fatal familial insomnia
What macromolecule makes up viral spikes?
- Glycoprotein
Which two retroviruses form proviruses and can quietly persist in host cells for more than a decade before emerging to cause leukemia or lymphoma?
- HTLV-1 and HTLV-2 (Human T-lymphotropic virsuses)
7) List three general virus capsid shapes.
- Helical - Icosahedral - Catchall complex
Name the glycoproteins that produce "HA" and "NA" spikes, which are represented by the H and N, respectively, in H1N1.
- Hemagglutinin and neuraminidase
Which type of acquired CJD is caused by accidental transmission to a patient as a result of a medical intervention.
- Iatrogenic CJD
8) What capsid shape is the SARS-CoV-2 virus?
- Icosahedral
When would temperate phages, such as lambda phages, revert from a lysogenic pathway to a lytic pathway?
- If the host cell carrying a prophage is stressed
9) What macromolecule makes up a viral envelope?
- Lipids
2a) Can viruses synthesize their nucleic acids and proteins apart from its host?
- No, they cannot
21) Do attenuated virus strains cause disease in healthy, non-immunocompromised hosts?
- No, they do not
1) List four properties that are used for classifying viruses.
- Nucleic acid - Capsid symmetry - Presence/absence of an envelope - Genome architecture
Human immunodeficiency virus (HIV), the etiological agent of AIDS, is a retrovirus. What would be the best choice of drugs that would specifically inhibit making a DNA copy of the HIV genome? (HINT: what enzyme makes a DNA copy of the HIV RNA genome?)
- Nucleoside reverse transcriptase inhibitors (NRTI's)
12) What is another term for viral spikes?
- Peplomers
10) Use the information in Training: Tomorrow's Health Team, Keeping HIV Quiet to answer the following question. A) What is one of the most important advances in HIV treatment for healthcare providers who may have been exposed to HIV?
- Postexposure prophylaxis (PEP) or preventing the infection from starting
Viruses and prions are both acellular infect agents. List two main differences between viruses and prions.
- Prions do not have genetic material and they do not replicate
5) What is a capsid and what macromolecule makes up the capsid?
- Protein cell that packages and protects the genome;
18) What enzyme is used by single-stranded antisense RNA (ssRNA-) viruses to make mRNA from an RNA template?
- RNA- dependent RNA polymerases (RdRPs)
Which test is the "gold standard" test when detecting SARS-CoV-2 infection?
- RT-PCR test
A) What two categories of testing options are currently used to detect active SARS-CoV-2 infections?
- Reverse transcription-PCR (RT-PCR) tests and antigen tests
What viral protein is coded for by Pfizer and Moderna SARS-CoV-2 vaccines, which is then produced by the host?
- SARS-CoV-2 spike protein
Define sensitivity and specificity in reference to diagnostic testing methods.
- Sensitivity: ability to detect low levels of the target - Specificity: reliability to detect only the viruses of interest
Define acute infection.
- Severe but short-lived; cleared by host immune system
What is the current theory about how normal prion proteins become misfolded?
- The misfolded infectious version of the prion protein makes contact with the normal version, causing changes to the normal proteins shape.
You are testing a patient's blood using an agglutination test. Latex beads are coated with antibodies that are specific to human immunodeficiency virus (HIV). When the beads and blood are mixed, agglutination occurs. What does this test result indicate?
- The sample contains the viral antigen HIV
You are testing a patient's blood using an agglutination test. Latex beads are coated with herpes virus-1 virions. When the beads and the blood are mixed, no agglutination occurs. What does this test result indicate?
- The sample does not contain the viral antigen
22) Define tropism.
- The type of cells/tissue viruses infect
Which type of acquired Creutzfeldt-Jakob disease (CJD) has been given the name "mad cow disease"?
- Variant CJD
10) What is a "naked" virion?
- Virions without an envelope
Tamiflu® is used to treat Influenza A. What mode of action does Tamiflu® use?
- Virus release
Certain viruses, like Ebola, are said to have a broad tropism. What does that mean?
- Viruses that can infect a wide range of host cells or tissues
The Pfizer and Moderna SARS-CoV-2 vaccines use which immunization strategy?
- mRNA vaccination
Name the two new immunization strategies for SARS-CoV-2 vaccines.
- mRNA vaccinations - Vector vaccinations
17) Which type of single-stranded RNA virus genome functions directly as mRNA?
- ssRNA
whats the temp range of a psychophile?
-20 to 10 degrees celcius
whats the degree of a psychotroph
0-30 degrees C
What temp are mesophiles found?
20-45C
degree of a thermophile
40 to 75 degrees C
capsomeres are
6) Three-dimensional subunits whose arrangement determines a capsid's shape are called capsomeres
degree of an extreme thermophile
65-120 degrees c
U.S. Centers for Disease Control and Prevention (CDC) reports that about ..... percent of all cervical cancer cases are linked to HPV.
90%
5) True or False: If the answer is "false", correct the statement.
A) Viruses are not classified into domains, but their highest taxonomic classification is kingdom. - False; the order level is the highest taxonomic classification level
In an______ infection, viral replication peaks, followed by immune clearance of the virus
Acute
Which of the following methods is used to cultivate bacteriophages in the laboratory setting?
Bacteriophages are cultivated in bacteria in liquid broth or on solid medium.
Which of the following is NOT a mechanism of an antiviral drug?
Blocking viral ribosomes.
Which of the following statements are incorrect about the transmission of Creutzfeldt-Jakob disease?
Creutzfeldt-Jakob disease is never inherited Creutzfeldt-Jakob disease can be transmitted through respiratory droplets.
15) The influenza virus that causes swine flu is called
H1N1.
Which of the following oncogenic viruses may integrate into the host genome?
Human Papilloma Viruses (HPV) Human T-Lymphotropic Viruses (HTLV)
Which of the following steps is found in the lysogenic replication pathway but NOT in the lytic replication pathway?
Integration
11) ...... infections differ from chronic persistent infections by their characteristic flare-ups with intermittent periods of dormancy.
Latent
Which type of method is used to determine if a prior exposure to a virus occurred?
Latex agglutination test
Do the SARS-CoV-2 vaccine produced by Pfizer, Moderna, or Johnson and Johnson change your DNA? Why or why not?
Neither vaccine strategies alter DNA
12) ....... analogs are drugs that block nucleic acid replication.
Nucleoside
The most common drugs that block replication are _________ _______.
Nucleoside analogs
...... are proteinaceous infectious particles
Prions
20) RNA viruses mutate more quickly than DNA viruses because
RNA polymerases do not have the proofreading capabilities that DNA polymerases do.
Which of the following statements are true about SARS-CoV-2?
SARS-CoV-2 causes Covid-19 The genome of SARS-CoV-2 undergoes mutations
Which of the following is NOT a property used to group viruses?
Unicellularity versus multicellularity
The Johnson and Johnson SARS-CoV-2 vaccine use which immunization strategy?
Vector vaccine
Which of the following would be the BEST general description of a virus?
Viruses are acellular infectious agents.
4) A single infectious virus particle is called
a virion.
Viral replication can be blocked by short sequences of nucleotides that are complementary to the RNA transcribed by specific viruses called
antisense antivirals.
14) Viral spikes
bind to specific factors on a host cell which determines the exact cell type a virus can infect.
what is a halogen
bleach
HIV treatment usually includes administration of the NRTI drug
called azidothymidine (also known as AZT
12) Human herpes virus-1 (HHV-1, also known as HSV-1) is known to lie dormant in host nerve cells and then reemerge to generate ??????
cold sores.
