Virology Final

What does the abbreviation "PFU" stand for? (A) Permissive Factor Unit (B) Plaque Forming Unit (C) Plasmid Foci Unit

(B) Plaque Forming Unit

Hershey and Chase studied the replication of bacteriophages. Their data demonstrated what? (A) That viruses can have many different types of nucleic acid (B) That nucleic acid, is physically transferred from "parents" to "progeny" virus (C) That viruses can differ widely in "specific infectivity" (D) Bacteriophages are viruses that infect bacteria

(B) That nucleic acid, is physically transferred from "parents" to "progeny" virus

For the eukaryotic host cell, DNA replication occurs by which of the following mechanisms (chose one)? (A) Strand displacement (B) Cap snatching (C) Bidirectional replication fork (D) TATA box recognition (E) Rolling circle

(C) Bidirectional replication fork

In what order would you predict these mRNAs classes to appear in the cytoplasm? (A) All at the same time (B) No order/random (C) 9-4-2 (D) 2-4-9

2-4-9

Major barriers of skin, eyes, and urogenital tract

Keratinized skin layers Mucosal and fluid secretions

Avirulent

Lack ability to cause disease

Attenuated

Less virulent, weakened. Something that has been done to the pathogen

Multiplicity of Infection (MOI)=

MOI given= x/# of cells

Nosocomial Transmission

hospital acquired infection

Specific Infectivity=

# of particles counted (given)/ concentration of stock units= (particles/pfu)

Select the best option for the possible purposes or functions of each mRNA class. (1) 2 kb (2) 4 kb (3) 9 kb (A) activation of the PKR, antiviral state (B) Translation into viral protein(s) (C) Packing as progeny genome (D) Either B or C (E) None of the above

(1) 2 kb: (B) Translation into viral protein(s) (2) 4 kb: (B) Translation into viral protein(s) (3) 9 kb: (D) Either B or C

List the 4 stages of virus entry.

(1) Attachment (2) Internilization (3) Penetration (4) Genome Release

What are the three potential "functions" of a virus-receptor interaction?

(1) Attachment/Adhesion (2) Signaling Pathway (signal transduction) (3) Triggering Membrane Penetration

Which of the statements below is most true about herpes simplex virus? (A) Latency involves an alternative transcriptional regulation where the IE genes are not expressed. (B) Latency results from a different type of receptor interaction during entry. (C) Latency reflects a switch from temporal cascade to autoregulatory modes of transcriptional regulation. (D) All of the above (E) None of the above

(A)- Latency involves an alternative transcriptional regulation where the IE genes are not expressed.

What are the several unusual features of poxvirus assembly and egress. Select 4 (1) Envelopment by non-vesicular, cytoplasmic membranes called "crescents" (2) De-envelopment at the outer nuclear membrane, and re-envelopment at the trans-Golgi network (3) An intracellular morphogenesis stage in which virions have three envelopes (4) Direct cell-to-cell spread without assembly of intact progeny virions (5) Cell-to-cell spread facilitated by polymerization cellular actin (6) Transport of progeny along nerve cell axons by microtubules, and motor proteins (7) Two forms of infectious progeny that have different envelopes

(1) Envelopment by non-vesicular, cytoplasmic membranes called "crescents" (3) An intracellular morphogenesis stage in which virions have three envelopes (5) Cell-to-cell spread facilitated by polymerization cellular actin (7) Two forms of infectious progeny that have different envelopes

Match the Strategy With the Best Description (1) Polyprotein (2) Leaking Scanning (3) Suppression of Termination (read-through) (4) Ribosome Frameshift (5) Ribosome Reinitiation (6) Internal Ribosome Entry Site Description (A) Removal of different intron sequences from pre-mRNA to yield distinct mRNAs (B) After recognition of a stop codon and release of a polypeptide, the ribosome continues along the same mRNA to another start codon, and beings translation of another open reading frame (C) Proteolytic release of many smaller proteins from one larger, precursor polypeptide (D) A secondary structure that allows recognition of the viral mRNA by the ribosome in a cap-independent manner (E) The ribosome can initiate translation at any of several start coons. The frequency of usage of each potential start codon depends largely on the strength of its Kozak context. (F) The use of different transcription promoters (G) During translation, the ribosome occasionally slips back one or two nucleotides, and then continues with translation (H) On some mRNAs, the ribosome ends translation at a stop codon, on other copies of the same mRNA, translation continues until a downstream stop codon

(1) Polyprotein (C): Proteolytic release of many smaller proteins from one larger, precursor polypeptide (2) Leaking Scanning (E): The ribosome can initiate translation at any of several start coons. The frequency of usage of each potential start codon depends largely on the strength of its Kozak context. (3) Suppression of Termination (read-through) (H): On some mRNas, the ribosome ends translation at a stop codon, on other copies of the same mRNA, translation continues until a downstream stop codon (4) Ribosome Frameshift (G): During translation, the ribosome occasionally slips back one or two nucleotides, and then continues with translation (5) Ribosome Reinitiation (B): After recognition of a stop codon and release of a polypeptide, the ribosome continues along the same mRNA to another start codon, and beings translation of another open reading frame (6) Internal Ribosome Entry Site (D): A secondary structure that allows recognition of the viral mRNA by the ribosome in a cap-independent manner

What are the two most common "triggers" for the conformational changes in viral proteins that mediate fusion, or other membrane interactions that facilitate entry?

(1): Low pH (2): Receptor Binding

Match the Characteristics common to Viral Fusion Proteins. Indicate which characteristics apply to class I, II, and III viral fusion proteins. (A) Alpha Helical Coiled-Coils (B) Pre-Fusion Homotrimer (C) Fusion Peptide (D) Beta-Sheets (E) Fusion Loops (F) Metastable Conformation

(A) Alpha Helical Coiled-Coils: I & III (B) Pre-Fusion Homotrimer: I & III (C) Fusion Peptide: I (D) Beta-Sheets: II & III (E) Fusion Loops: II & III (F) Metastable Conformation: I, II, III

During HIV replication, three classes of viral mRNAs are produced by what process? (A) Alternative splicing (B) Polymerase stuttering (C) Cap snatching (D) Suppression of ribosome termination (E) All of the Above (F) None of the above

(A) Alternative Splicing

Choose the most appropriate virology term for each statement. (A) Cell that can support productive viral replication (B) Cell that can support viral attachment and entry (C) Cell that cannot support viral attachment and entry Options (1) Infectious (2) Susceptible (3) Resistant (4) Immune (5) Permissive

(A) Cell that can support productive viral replication: PERMISSIVE (5) (B) Cell that can support viral attachment and entry: SUSCEPTIBLE (2) (C) Cell that cannot support viral attachment and entry: RESISTANT (3)

What does the abbreviation/acronym "CPE" stand for? (A) Cytopathic Effects (B) Capsids per Envelope (C) Cellular Permissive Environment (D) Cis-productive Element

(A) Cytopathic Effects

Heshey and Chase studied the replication of bacteriophages. Their work help establish which ONE of the following molecular biology principles? (A) Nucleic acid, not protein is "genetic material" (B) Polymerase chain reaction (PCR) (C) "Central dogma of molecular biology" (DNA>RNA>Protein) (D) Double helix DNA

(A) Nucleic acid, not protein is "genetic material"

What characteristics applies to Icosahedral Capsids, Helical Capsids, Neither, or Both? (A) Open Structure (B) Closed Structure (C) Repetitive, equivalent interactions among subunits

(A) Open Structure: Helical Capsid (B) Closed Structure: Icosahedral Capsid (C) Repetitive, equivalent interactions among subunits: Both Helical & Icosahedral

Select TWO best descriptions of the "antiviral state" activity of RNA activated-protein kinase (PKR) (A) Phosphorylates translation factor, eIF2a (B) Degrades viral mRNA (C) Specifically inhibits viral mRNA translation (D) Inhibits all mRNA translation (viral and host) (E) Blocks pre-mRNA splicing

(A) Phosphorylates translation factor, eIF2a (D) Inhibits all mRNA translation (viral and host)

Which TWO of the following are strategies by which viruses can inhibit host protein synthesis, thereby favoring viral protein synthesis? (A) RNase degradation of mRNA (B) Alternative splicing (C) Autoregulatory feedback loop (D) Cleavage of cap-binding factor, eIF-4E (E) RNaseH degradation of RNA:DNA duplex

(A) RNase degradation of mRNA (D) Cleavage of cap-bind factor, eIF-4E

DNA viruses can avoid the problem of shorting ends during DNA replication by (all that apply) (A) Rolling circle replication (B) Circular genomes (not having ends) (C) Terminal origin of replication (D) Stem and loop formation (E) Cytoplasmic replication (F) Encoding their own DNA polymerases

(A) Rolling circle replication (B) Circular genomes (not having ends) (C) Terminal origin of replication

The nature of DNA virus genomes can be: (A) dsDNA (B) ssDNA (C) DNA/RNA Hybrid (D) Double strand with gaps (E) Circular (F) Linear

(A) dsDNA (B) ssDNA (D) Double stranded with gaps (E) Circular (F) Linear

Resting cells can be poor hosts for DNA virus replication because they: (A) Lack receptors (B) Do not have abundant DNA metabolism factors (C) Express interferon (D) Are closely monitored by the host immune system

(B) Do not have abundant DNA metabolism factors

The oncogenic nature of viruses like HPV is due in part to (choose one): (A) HPV binds to host cell receptors (B) HPV proteins are toxic (C) HPV encodes a protein that induces cell cycle progression by bind to the host retinoblastoma (Rb) protein (D) HPV induces mutations in the host cell genome

(C) HPV encodes a protein that induces cell cycle progression by binding to the host retinoblastoma (Rb) protein

Which one of the following statements best explains why HPV infection can lead to cancer? (A) HPV origin binding proteins can "cross-react" with host DNA and stimulate cell division (B) HPV proteins can induce mutations in the host cell genome (C) HPV proteins can block the activity of retinoblastoma (Rb) protein, which regulates the cell cycle (D) HPV expresses a homolog of telomerase, which prevents telomere shortening

(C) HPV proteins can block the activity of retinoblastoma (Rb) protein, which regulates the cell cycle

The anti-herpesvirus drug, acyclovir works because? (A) HSV infects both actively dividing cells, like epithelial cells, and non-dividing cells, like neurons (B) DNA viruses, like HSV are more genetically stable than RNA viruses (C) HSV encodes many of its own DNA synthesis enzyme (D) HSV uses rolling circle replication

(C) HSV encodes many of its own DNA synthesis enzymes

Which of the following statements about DNA virus mRNA production are true? (A) Most DNA viruses encode all of their own mRNA transcription machinery, including polymerases, and transcription factors. (B) DNA viruses do not need to make mRNA to facilitate their replication cycle. (C) Most DNA viruses utilize host cell RNA pol II to make their mRNA. (D) Herpes simplex virus brings in its own RNA pol as part of its tegument layer. (E) Some DNA viruses encode proteins that regulate the transcription of their genes by host RNA pol II

(C) Most DNA viruses utilize host cell RNA pol II to make their mRNA (E) Some DNA viruses encode proteins that regulate the transcription of their genes by host RNA pol II

Specific Infectivity refers to what? (A) The binding of a virus to a specific cellular receptor (B) The number of viruses infecting each cell (C) The quantification of viruses as both physical particles, and replication-competent, biological entities (D) What kind of nucleic acid (RNA or DNA) the viral genome is made of

(C) The quantification of viruses as both physical particles, and replication-competent, biological entities

ALL viruses require that host cell to provide what? (A) DNA replicaiton (B) Transcription of DNA into mRNA (C) Translation of mRNA to protein (D) Lipid metabolism

(C) Translation of mRNA to protein

For the eukaryotic host cell, each successive round of DNA replication is characterized by loss of sequence from the end of chromosomes. From the list below, select the best explanation of why. (A) The RNAase H domain of DNA pol degrades the ends of the parental template strand as it synthesizes the new strand. (B) Secondary structures on the ends of the chromosomes block DNA pol (C) When the last RNA primer is removed from the either end of newly replicated chromosome, there is no free 3'OH to serve as a primer for DNA pol to fill in the gap. (D) The ends of the chromosomes consist of long stretches of repeat sequences, which cause the DNA pol to "stutter".

(C) When the last RNA primer is removed from either end of mewl replicated chromosome, there is no free 3' OH to serve as a primer for DNA pol to fill in the gap

Which of the following statements about herpes simplex virus VP16 is most true? (A) VP16 is a transcription factor that directly binds to sequences within viral IE promoters. (B) VP16 is absolutely required for transcription from viral IE promoters. (C) VP16 is a protein in the mature, infectious HSV virion, and is delivered into the cell during entry. (D) VP16 binds a stem-loop structure on nascent mRNA and enhances promoter clearance.

(C)- VP16 is a protein in the mature, infectious HSV virion, and is delivered into the cell during entry.

Which of the following is a plausible explanation for why genome replication can enhance the level of viral mRNA transcription? (A) Every new copy of the virus genome is another potential template for host RNA pol II. (B) The increased number of genomes can "dilute out" cellular factors that repress viral transcription. (C) All of the above (D) None of the above

(C)- all of the above

Viral genomes may consist of any of the following types of nucleic acid, except? (A) ssDNA (B) ssRNA (C) dsRNA (D) RNA/DNA Duplex (E) dsDNA

(D) RNA/DNA Duplex

Viral disease is a result of what?

1) Virus replication in the host 2) Host response to the virus 3) Effects of the host response on the host

Physical barriers of alimentary tract (GI tract)

Epithelium/mucus low pH (stomach) Proteases (stomach) High pH (intestines) Bile detergens (intestines)

Virulent

Ability to cause disease

Neurovirulent

Ability to cause infection of the nervous system

Match the term with the proper definition Autoregulatory and Temporal Cascade (A) The protein product(s) of one transcriptional unit of a virus genome up or down regulates the transcription of a distinct transcriptional unit(s) on the same virus genome. (B) The expression of distinct viral transcriptional units is regulated according to time during infection. (C) The protein product of one transcriptional unit up or down regulates transcription of "its own" transcriptional unit. (D) The expression of viral transcriptional units is regulated entirely by host cell factors.

Autoregulatory: (C)- The protein product of one transcriptional unit up or down regulates transcription of "its own" transcriptional unit. Temporal Cascade: (A)- The protein product(s) of one transcriptional unit of a virus genome up or down regulates the transcription of a distinct transcriptional unit(s) on the same virus genome.

How are physical barriers breeched?

Damage/Irritation open wounds needle punctures animal bites desiccation of mucus damage from bacterial/fungus infections

T/F By definition, a "virus" has only one transcriptional unit?

False

T/F Some DNA viruses rely 100% on host cell mechanisms for genome replication and do not encode any necessary DNA replication proteins in their own genome

False

Match appropriate entry strategy with the type of virus indicated. -Fusion -Pore Formation -Membrane Disruption -Endocytosis (A) Enveloped Virus (B) Naked/ Non-enveloped Virus (C) Both (D) Neither

Fusion: Enveloped Virus (A) Pore Formation: Naked/Non-enveloped Virus (B) Membrane Disruption: Naked/Non-Enveloped Virus (B) Endocytosis: Both (C)

Intrinsic Response

Individual cell response to infection -detecting infection -alerting the innate and adaptive response -interfering with viral replication -usually damaging to virus and host cell and surrounding tissue

Iatrogenic Transmission

Infection caused by medical examination or treatment

Vertical Transmission

Mother to child closely before and after birth

Major barriers of respiratory tract

Mucus Ciliary movement

Innate Response

Specialized effector and regulatory cells: NK cells, granulocytes, phagocytes Specialized effector and regulatory proteins: cytokines, complement NOT specific

Acquired Response

Specialized effector cells and proteins Highly specific Provides memory/immunity

Neurotropic

Tending to attack of affect the nervous system preferentially

Horizontal Transmission

Transmitted among individuals of the same generation

T/F All known DNA viruses require de novo synthesis of at least one of their own encoded proteins in order to begin replication of their genome.

True

T/F Viruses with RNA or ssDNA genomes must convert their genomes to dsDNA in order to utilize the host cell RNA pol II for mRNA production?

True

T/F Conversion to fully double stranded DNA is a prerequisite for virus DNA replication

True

Neuroinvasive

Viral infection that can spread through the nervous system

Viremia

presence of viruses in the blood free virus floating around virus stuck inside of a cell