VETM*3450: Module 3 (Viruses & Prions) || A+ Graded
Already.
What are *viruses*? [definition] correct answers submicroscopic, obligate intracellular
parasites; infectious agents (20 nm - 300 nm)
Which of the following is NOT a consistent characteristic among viruses?
a) they have one type of nucleic acid (RNA or DNA)
b) they reproduce only from their nucleic acid and do not "grow" or undergo division
c) they use of host ribosomal and tRNA for protein synthesis
d) they have few enzymes enzymes for energy metabolism
e) none of the above correct answers a) they have one type of nucleic acid (RNA or DNA)
b) they reproduce only from their nucleic acid and do not "grow" or undergo division
c) they use of host ribosomal and tRNA for protein synthesis
*d) they have few enzymes enzymes for energy metabolism*
e) none of the above
^d) is false b/c viruses do not have *any enzymes for energy metabolism
Which of the following can pass through bacteriological filters?
a) viruses
b) prions
c) both
d) neither correct answers a) viruses
b) prions
*c) both*
d) neither
What is the *virion*? correct answers the entire infectious unit form of a virus (outside of a
host cell w nucleic acid + capsid)
What are the components of the *virion*? correct answers entire infectious unit
What is a *capsid*? correct answers the protein coat surrounding the genetic material of a
virus
What is the *nucleocapsid*? correct answers the capsid together with the nucleic acid (of a
virus)
T/F: "All viruses have nucleic acid, a capsid, and an envelope." correct answers False; the
envelope is not always present
Types of macromolecules found in viruses? [chemical composition] correct answers ◽
nucleic acids
◽ proteins
◽ lipids
◽ carbohydrates
Functions of viral proteins? correct answers ◽ transfer & protect nucleic acids
,◽ packaging and/or condensation
◽ structural symmetry
◽ *specificity for attachment*
◽ *antigenic characteristics*
◽ enzymes
What are the two theories for the origin of viruses? correct answers 1) degenerate bacteria
with lost cellular function
2) escaped eukaryotic genes
In viruses that have an envelope, what is it composed of? [chemical composition] correct
answers lipoprotein
T/F: "Enveloped viruses are more sensitive to disinfectants, solvents, and environmental
effects than non-enveloped viruses." correct answers True; the surface envelope is fragile, so
they are more vulnerable
What are the three symmetrical forms the viral capsid can take? correct answers ◽
icosahedral
◽ helical
◽ complex
What is the difference between each of the following type of *capsid symmetry*?
a) icosahedral
b) helical
c) complex correct answers a) *icosahedral* - the capsid forms a regular icosahedron,
composed of 20 faces, each of which is an equilateral triangle
b) *helical* - the capsomers may be directly attached to the nucleic acid in the form of a helix
c) *complex* - unique structure (pox viruses)
Why is knowledge of stability of viral infectivity important? correct answers ◽ for
preservation of viral infectivity in clinical specimens collected for diagnosis and in reference
reagents
◽ for deliberate inactivation (stertilization, disinfection)
◽ for production of inactivated vaccines
Factors that affect stability of viruses? [4] correct answers ◽ temperature
◽ ionic environment
◽ pH
◽ lipid solvents/ detergents
pH to inactivate most viruses? correct answers 4.0 > pH > 9.0
Main criteria considered in the current taxonomy of viruses themselves? correct answers 1)
the type and character of the viral nucleic acid
2) the strategy of viral replication
3) the structure of the virion
(though other properties like size, morphology, antigenicity, mode of transmission, etc. are
also important)
,Taxonomic classifications of viruses? correct answers ◽ Order
◽ Family
◽ Subfamily
◽ Genus
◽ Species
^ families of viruses are important in veterinary medicine
Suffix "-virales" indicates which taxon?
a) Order
b) Family
c) Subfamily
d) Genus
e) Species correct answers *a) Order*
b) Family
c) Subfamily
d) Genus
e) Species
ex. Mononegavirales
Suffix "-virus" indicates which taxon?
a) Order
b) Family
c) Subfamily
d) Genus
e) Species correct answers a) Order
b) Family
c) Subfamily
*d) Genus*
e) Species
ex. avulavirus
Suffix "-viridae" indicates which taxon?
a) Order
b) Family
c) Subfamily
d) Genus
e) Species correct answers a) Order
*b) Family*
c) Subfamily
d) Genus
e) Species
ex. Paramyxoviridae
Suffix "-virinae" indicates which taxon?
a) Order
, b) Family
c) Subfamily
d) Genus
e) Species correct answers a) Order
b) Family
*c) Subfamily*
d) Genus
e) Species
ex. Paramyxovirina
In which of the following cases is a cell said to be *resistant* to a virus?
a) no receptor for the virus on the cell, so cell not infected
b) receptor is present on the cell but the virus does not infect the cells bc the virus is blocked
by antibody
c) the virus infects the cell but its replication is inhibited by interferon
d) the virus infects the cell but the cell lacks the enzymes the virus needs to replicate
e) all of the above correct answers *a) no receptor for the virus on the cell, so cell not
infected*
b) receptor is present on the cell but the virus does not infect the cells bc the virus is blocked
by antibody
c) the virus infects the cell but its replication is inhibited by interferon
d) the virus infects the cell but the cell lacks the enzymes the virus needs to replicate
e) all of the above
T/F: "A cell that has a persistent viral infection, where the virus is able to replicate without
killing the cell, will continue to undergo normal cell division." correct answers True
T/F: "Cell division is halted in a cell that has a persistent viral infection, where the virus is
able to replicate without killing the cell." correct answers False; the cell will continue with
normal cell division
Steps in viral infection process? correct answers 1) Entry into host (portal of entry) and
primary viral replication
2) Local and general spread of the virus within the host, cell infection, and tissue damage
3) Evasion of host defense (inflammatory response and immune defense)
4) Shedding of viruses
5) Cause damage to host
Mechanisms of viral disease? correct answers ◽ Direct cell damage
◽ Cell transformation (tumour)
◽ Inflammatory response, Immune response
◽ Immunosuppression
◽ Predisposition to bacterial infection
Potential outcomes of virus-animal association? correct answers 1) *Animal is resistant* →
no relationship
2) *Asymptomatic infection* → recovery, immunity, persistent infection
3) *Acute infection* → death, recovery (immunity), persistent infection
4) *Chronic infection* → recurrent clinical disease, persistent infection
Already.
What are *viruses*? [definition] correct answers submicroscopic, obligate intracellular
parasites; infectious agents (20 nm - 300 nm)
Which of the following is NOT a consistent characteristic among viruses?
a) they have one type of nucleic acid (RNA or DNA)
b) they reproduce only from their nucleic acid and do not "grow" or undergo division
c) they use of host ribosomal and tRNA for protein synthesis
d) they have few enzymes enzymes for energy metabolism
e) none of the above correct answers a) they have one type of nucleic acid (RNA or DNA)
b) they reproduce only from their nucleic acid and do not "grow" or undergo division
c) they use of host ribosomal and tRNA for protein synthesis
*d) they have few enzymes enzymes for energy metabolism*
e) none of the above
^d) is false b/c viruses do not have *any enzymes for energy metabolism
Which of the following can pass through bacteriological filters?
a) viruses
b) prions
c) both
d) neither correct answers a) viruses
b) prions
*c) both*
d) neither
What is the *virion*? correct answers the entire infectious unit form of a virus (outside of a
host cell w nucleic acid + capsid)
What are the components of the *virion*? correct answers entire infectious unit
What is a *capsid*? correct answers the protein coat surrounding the genetic material of a
virus
What is the *nucleocapsid*? correct answers the capsid together with the nucleic acid (of a
virus)
T/F: "All viruses have nucleic acid, a capsid, and an envelope." correct answers False; the
envelope is not always present
Types of macromolecules found in viruses? [chemical composition] correct answers ◽
nucleic acids
◽ proteins
◽ lipids
◽ carbohydrates
Functions of viral proteins? correct answers ◽ transfer & protect nucleic acids
,◽ packaging and/or condensation
◽ structural symmetry
◽ *specificity for attachment*
◽ *antigenic characteristics*
◽ enzymes
What are the two theories for the origin of viruses? correct answers 1) degenerate bacteria
with lost cellular function
2) escaped eukaryotic genes
In viruses that have an envelope, what is it composed of? [chemical composition] correct
answers lipoprotein
T/F: "Enveloped viruses are more sensitive to disinfectants, solvents, and environmental
effects than non-enveloped viruses." correct answers True; the surface envelope is fragile, so
they are more vulnerable
What are the three symmetrical forms the viral capsid can take? correct answers ◽
icosahedral
◽ helical
◽ complex
What is the difference between each of the following type of *capsid symmetry*?
a) icosahedral
b) helical
c) complex correct answers a) *icosahedral* - the capsid forms a regular icosahedron,
composed of 20 faces, each of which is an equilateral triangle
b) *helical* - the capsomers may be directly attached to the nucleic acid in the form of a helix
c) *complex* - unique structure (pox viruses)
Why is knowledge of stability of viral infectivity important? correct answers ◽ for
preservation of viral infectivity in clinical specimens collected for diagnosis and in reference
reagents
◽ for deliberate inactivation (stertilization, disinfection)
◽ for production of inactivated vaccines
Factors that affect stability of viruses? [4] correct answers ◽ temperature
◽ ionic environment
◽ pH
◽ lipid solvents/ detergents
pH to inactivate most viruses? correct answers 4.0 > pH > 9.0
Main criteria considered in the current taxonomy of viruses themselves? correct answers 1)
the type and character of the viral nucleic acid
2) the strategy of viral replication
3) the structure of the virion
(though other properties like size, morphology, antigenicity, mode of transmission, etc. are
also important)
,Taxonomic classifications of viruses? correct answers ◽ Order
◽ Family
◽ Subfamily
◽ Genus
◽ Species
^ families of viruses are important in veterinary medicine
Suffix "-virales" indicates which taxon?
a) Order
b) Family
c) Subfamily
d) Genus
e) Species correct answers *a) Order*
b) Family
c) Subfamily
d) Genus
e) Species
ex. Mononegavirales
Suffix "-virus" indicates which taxon?
a) Order
b) Family
c) Subfamily
d) Genus
e) Species correct answers a) Order
b) Family
c) Subfamily
*d) Genus*
e) Species
ex. avulavirus
Suffix "-viridae" indicates which taxon?
a) Order
b) Family
c) Subfamily
d) Genus
e) Species correct answers a) Order
*b) Family*
c) Subfamily
d) Genus
e) Species
ex. Paramyxoviridae
Suffix "-virinae" indicates which taxon?
a) Order
, b) Family
c) Subfamily
d) Genus
e) Species correct answers a) Order
b) Family
*c) Subfamily*
d) Genus
e) Species
ex. Paramyxovirina
In which of the following cases is a cell said to be *resistant* to a virus?
a) no receptor for the virus on the cell, so cell not infected
b) receptor is present on the cell but the virus does not infect the cells bc the virus is blocked
by antibody
c) the virus infects the cell but its replication is inhibited by interferon
d) the virus infects the cell but the cell lacks the enzymes the virus needs to replicate
e) all of the above correct answers *a) no receptor for the virus on the cell, so cell not
infected*
b) receptor is present on the cell but the virus does not infect the cells bc the virus is blocked
by antibody
c) the virus infects the cell but its replication is inhibited by interferon
d) the virus infects the cell but the cell lacks the enzymes the virus needs to replicate
e) all of the above
T/F: "A cell that has a persistent viral infection, where the virus is able to replicate without
killing the cell, will continue to undergo normal cell division." correct answers True
T/F: "Cell division is halted in a cell that has a persistent viral infection, where the virus is
able to replicate without killing the cell." correct answers False; the cell will continue with
normal cell division
Steps in viral infection process? correct answers 1) Entry into host (portal of entry) and
primary viral replication
2) Local and general spread of the virus within the host, cell infection, and tissue damage
3) Evasion of host defense (inflammatory response and immune defense)
4) Shedding of viruses
5) Cause damage to host
Mechanisms of viral disease? correct answers ◽ Direct cell damage
◽ Cell transformation (tumour)
◽ Inflammatory response, Immune response
◽ Immunosuppression
◽ Predisposition to bacterial infection
Potential outcomes of virus-animal association? correct answers 1) *Animal is resistant* →
no relationship
2) *Asymptomatic infection* → recovery, immunity, persistent infection
3) *Acute infection* → death, recovery (immunity), persistent infection
4) *Chronic infection* → recurrent clinical disease, persistent infection
