p.50
Chemical Composition of Viruses
What type of RNA do Flaviviruses contain?
Single-stranded, positive-sense RNA.
p.110
Antiviral Chemotherapy and Molecular Virology
What is a key requirement for antiviral agents?
They must selectively inhibit viral functions without damaging the host.
p.108
Classification of Viruses
What does 'non-attenuated' refer to in the context of viruses?
Viruses that have not been weakened and can cause disease.
p.67
Definition and Characteristics of Viruses
How are prions resistant to inactivation?
They are highly resistant to heat, formaldehyde, and ultraviolet light that inactivate viruses.
p.46
Classification of Viruses
What are arboviruses and rodent-borne viruses classified as?
Ecologic groupings, not a virus family.
p.106
Vaccination and Immunization
What is immunization?
The process of getting the vaccine and developing immunity to disease as a result.
p.107
Vaccination and Immunization
What is the benefit of attenuated live vaccines?
They mimic natural infection and provide lifelong immunity.
p.8
Classification of Viruses
How are viruses further classified beyond genetic material?
By their structure, symmetry, and mode of replication.
p.102
Host Defenses Against Viruses
What is cell-mediated immunity primarily associated with?
The response to intracellular pathogens.
p.113
Antiviral Chemotherapy and Molecular Virology
What is the function of amantadine and rimantadine?
They block viral uncoating.
p.75
Virus Structure and Symmetry
What types of viruses commonly exhibit helical symmetry?
Many RNA viruses and some DNA viruses.
p.37
RNA-Containing Virus Families
What are the main groups of enteroviruses that infect humans?
Polioviruses, coxsackieviruses, echoviruses, and rhinoviruses.
p.17
Viral Replication Cycle
Where does capsid assembly take place in an infected cell?
In the nucleus of the infected cell.
p.107
Vaccination and Immunization
What are live vaccines?
Vaccines that contain live organisms which have lost the capacity to cause disease but can still replicate in the host.
p.8
Classification of Viruses
What is the primary basis for classifying viruses?
The type of genetic material they contain (DNA or RNA).
p.112
Antiviral Chemotherapy and Molecular Virology
What is the role of integrase inhibitors?
They block the activity of viral integrase.
p.29
Virus Structure and Symmetry
What does the virus envelope contain?
Lipid and the viral surface antigen.
p.59
Classification of Viruses
What diseases do hantaviruses cause?
Hemorrhagic fevers, nephropathy, and severe pulmonary syndrome.
p.68
Definition and Characteristics of Viruses
What are prion diseases also known as?
Transmissible spongiform encephalopathies.
p.7
Classification of Viruses
What are the two main categories of viruses based on their nucleic acid?
DNA viruses and RNA viruses.
p.2
Viral Replication Cycle
What is produced during the viral replicative cycle?
Numerous copies of viral nucleic acid and coat proteins.
p.78
Definition and Characteristics of Viruses
Can you give an example of a complex structure?
An example of a complex structure is a protein, which is made up of amino acids folded into a specific shape.
p.6
Virus Structure and Symmetry
What is a subunit in viral structure?
A single folded viral polypeptide chain.
p.96
Host Defenses Against Viruses
What role do the immune system play in host defenses against viruses?
The immune system identifies and eliminates virus-infected cells and neutralizes free viruses.
p.79
Virus Structure and Symmetry
What type of symmetry do some virus particles exhibit?
More complicated structures than simple cubic or helical symmetry.
p.18
Definition and Characteristics of Viruses
What distinctive appearance does Fifth Disease cause?
A 'slapped cheek' appearance.
p.102
Host Defenses Against Viruses
What defines obligate intracellular pathogens?
Pathogens that cannot replicate outside of host cells.
p.17
Viral Replication Cycle
In which type of cells does replication occur for Human parvovirus B19?
Only in actively dividing cells.
p.99
Definition and Characteristics of Viruses
What is the capacity of Plasma IgM for binding antigenic epitopes?
5 times the capacity compared to other immunoglobulins.
p.99
Host Defenses Against Viruses
Why is IgM considered the most effective immunoglobulin isotype?
Because it effectively sponges free antigen out of the tissues.
p.47
Classification of Viruses
What types of hosts can arboviruses infect?
Humans, mammals, birds, and reptiles.
p.18
Definition and Characteristics of Viruses
What is another name for Fifth Disease?
Slapped cheek appearance.
p.102
Host Defenses Against Viruses
What are facultative intracellular pathogens?
Pathogens that are adapted to living inside phagocytic cells that are designed to kill them.
p.113
Antiviral Chemotherapy and Molecular Virology
What is the role of oseltamivir in antiviral treatment?
It prevents the release of influenza virus particles.
p.65
Classification of Viruses
What types of species are affected by emerging viruses?
Some are associated with human disease, while many affect other species.
p.2
Viral Replication Cycle
What does the viral nucleic acid contain?
Information necessary for the infected host cell to synthesize virus-specific macromolecules required for the production of viral progeny.
p.76
Virus Structure and Symmetry
What surrounds the helical nucleocapsid in animal viruses?
A lipid-containing envelope.
p.98
Definition and Characteristics of Viruses
Why is IgM critical during an antigenic challenge?
It maximizes the body's immune response early on.
p.69
Virus Structure and Symmetry
What is a viral envelope?
A viral envelope is a lipid membrane that surrounds some viruses, derived from the host cell's membrane.
p.84
Virus Structure and Symmetry
Where does budding occur during the viral maturation process?
At sites where virus-specific proteins have been inserted into the host cell membrane.
p.17
Host Defenses Against Viruses
What adverse consequences can Human parvovirus B19 cause?
Aplastic crisis, fifth disease, and fetal death.
p.19
DNA-Containing Virus Families
What is the size of Anelloviruses?
Approximately 30 nm in diameter.
p.7
Classification of Viruses
What is a viral family?
A group of related viruses classified together based on shared characteristics.
p.17
Viral Replication Cycle
In which specific cells does Human parvovirus B19 replicate?
In immature erythroid cells.
p.81
Chemical Composition of Viruses
What role do proteins play in the chemical composition of viruses?
Proteins form the viral capsid, which protects the nucleic acid and aids in the virus's infection of host cells.
p.114
Definition and Characteristics of Viruses
What is the purpose of expressing gratitude?
To acknowledge kindness or assistance received.
p.103
Host Defenses Against Viruses
What is immunodiagnostics?
A field of study that uses immune responses for diagnostic purposes.
p.74
Virus Structure and Symmetry
What do most preparations of isometric viruses contain?
Some 'empty' particles devoid of viral nucleic acid.
p.78
Definition and Characteristics of Viruses
What are complex structures in biological systems?
Complex structures refer to intricate arrangements of biological molecules, cells, and tissues that perform specific functions.
p.75
Virus Structure and Symmetry
What is the significance of helical symmetry in viral structure?
It allows for a compact and efficient packaging of the viral genome.
p.78
Definition and Characteristics of Viruses
Why are complex structures important in biology?
They enable organisms to perform various life processes efficiently.
p.75
Virus Structure and Symmetry
Can you give an example of a virus with helical symmetry?
Tobacco mosaic virus (TMV).
p.4
Definition and Characteristics of Viruses
What is a virion?
The entire infectious unit of a virus.
p.51
Definition and Characteristics of Viruses
What type of viruses are Arenaviruses?
Pleomorphic, enveloped viruses.
p.23
Definition and Characteristics of Viruses
What does the name Papillomavirus refer to?
Latin 'papilla' (nipple) and Greek 'oma' (tumor), describing wart-like lesions.
p.110
Antiviral Chemotherapy and Molecular Virology
When can antivirals be used?
To treat established infections when vaccines would not be effective.
p.75
Virus Structure and Symmetry
What is helical symmetry in viruses?
A type of virus structure where the protein subunits are arranged in a spiral around the nucleic acid.
p.76
Virus Structure and Symmetry
How are protein subunits arranged in relation to viral nucleic acid?
They are bound in a periodic way, winding it into a helix.
p.4
Definition and Characteristics of Viruses
What encases the nucleic acid in viruses?
A protein shell, which may be surrounded by a lipid-containing membrane.
p.64
Definition and Characteristics of Viruses
What type of viruses are Filoviridae?
Enveloped, pleomorphic viruses.
p.69
Virus Structure and Symmetry
What is the function of the viral capsid?
The capsid protects the viral genetic material and aids in the attachment and entry into host cells.
p.26
DNA-Containing Virus Families
What is the structure of the adenovirus genome?
Linear, double stranded DNA.
p.99
Host Defenses Against Viruses
What role does IgM play in the humoral immune response?
It traps antigens for presentation to lymphocytes.
p.49
Classification of Viruses
What is an example of a virus that matures by budding?
Eastern equine encephalitis virus.
p.81
Chemical Composition of Viruses
What are the primary components of viruses?
Viruses are primarily composed of nucleic acids (DNA or RNA) and proteins.
p.32
DNA-Containing Virus Families
What type of genome do poxviruses have?
Linear, covalently closed, double-stranded DNA.
p.8
Classification of Viruses
What is the significance of the viral replication cycle in classification?
The replication cycle can determine how viruses are grouped and understood in terms of their life cycle.
p.82
Virus Structure and Symmetry
How do viral proteins protect the viral genome?
By guarding against inactivation by nucleases.
p.34
Classification of Viruses
Can RNA-containing viruses be single-stranded or double-stranded?
Yes, they can be either single-stranded (ssRNA) or double-stranded (dsRNA).
p.81
Chemical Composition of Viruses
What is the significance of the viral envelope?
The viral envelope, if present, is composed of lipids and proteins and helps the virus to enter host cells.
p.29
Classification of Viruses
What type of infections can Hepadnaviruses like Hepatitis B virus cause?
Acute and chronic hepatitis.
p.81
Chemical Composition of Viruses
What are viral glycoproteins?
Viral glycoproteins are proteins with carbohydrate groups attached, important for the recognition and binding to host cells.
p.63
Definition and Characteristics of Viruses
What is a characteristic of the viruses that infect humans mentioned in the text?
They have narrow host ranges.
p.83
Classification of Viruses
What are the possible structures of a viral genome?
Single or double stranded, circular or linear, and segmented or nonsegmented.
p.4
Definition and Characteristics of Viruses
What are viruses?
Smallest infectious agents that contain only one nucleic acid as their genome (RNA or DNA).
p.98
Definition and Characteristics of Viruses
Can IgM be produced with or without help from T-cells?
Yes, IgM can be produced with or without cell help.
p.68
Definition and Characteristics of Viruses
What is scrapie?
A prion disease found in sheep.
p.98
Definition and Characteristics of Viruses
What is the structure of IgM that enhances its effectiveness?
IgM is designed as a pentamer.
p.49
Viral Replication Cycle
How do virus particles mature?
By budding from host cell membranes.
p.48
Classification of Viruses
What type of viruses belong to the H. Togaviridae family?
Alphaviruses and rubella virus.
p.5
Virus Structure and Symmetry
What is a capsid?
The protein shell or coat that encloses the nucleic acid genome.
p.78
Virus Structure and Symmetry
What role do complex structures play in viruses?
Complex structures in viruses, such as capsids and envelopes, help in infection and evasion of host defenses.
p.111
Antiviral Chemotherapy and Molecular Virology
What is the main focus of molecular virology studies?
Identifying virus-specific functions that can serve as targets for antiviral therapy.
p.67
Definition and Characteristics of Viruses
What are prions composed of?
Infectious particles composed solely of protein with no detectable nucleic acid.
p.112
Antiviral Chemotherapy and Molecular Virology
What do nucleoside analogs do?
Inhibit nucleoside replication.
p.74
Virus Structure and Symmetry
What occurs when capsid proteins are expressed from cloned genes?
Self-assembly and formation of empty 'virus-like particles.'
p.6
Virus Structure and Symmetry
What is a nucleocapsid?
The protein-nucleic acid complex representing the packaged form of the viral genome.
p.112
Antiviral Chemotherapy and Molecular Virology
What do protease inhibitors target?
They inhibit viral protease required at the late stage of the replicative cycle.
p.64
Virus Structure and Symmetry
What is the typical size of Filoviruses?
80 nm wide and about 1000 nm long.
p.5
Virus Structure and Symmetry
What are capsomeres?
Morphologic units seen in the electron microscope on the surface of icosahedral virus particles.
p.40
Virus Structure and Symmetry
How do caliciviruses compare in size to picornaviruses?
Caliciviruses are slightly larger, measuring 27 – 40 nm.
p.19
Virus Structure and Symmetry
What type of structure do Anelloviruses have?
Icosahedral virions that lack an envelope.
p.7
Classification of Viruses
What is the significance of the International Committee on Taxonomy of Viruses (ICTV)?
It establishes the classification and naming of viruses.
p.14
DNA-Containing Virus Families
What is a common feature of the Poxviridae family?
They are large, complex viruses that can replicate in the cytoplasm.
p.51
Viral Replication Cycle
How do Arenaviruses assemble?
Via budding on the plasma membrane.
p.51
Virus Structure and Symmetry
What gives Arenavirus particles a 'sandy' appearance?
The incorporation of host cell ribosomes during maturation.
p.113
Antiviral Chemotherapy and Molecular Virology
What do fusion inhibitors do?
They disrupt the fusion of the viral envelope with the cell membrane.
p.79
Virus Structure and Symmetry
What is found inside poxviruses?
A core and lateral bodies.
p.96
Host Defenses Against Viruses
What are host defenses?
The mechanisms by which a host organism protects itself against viral infections.
p.7
Classification of Viruses
How are viruses further classified beyond their nucleic acid type?
Based on their structure, symmetry, and the presence of an envelope.
p.72
Virus Structure and Symmetry
What type of symmetry is observed with animal viruses?
Cubic symmetry, specifically the icosahedral pattern.
p.37
RNA-Containing Virus Families
How do other enteroviruses compare to rhinoviruses in terms of acidity and density?
Other enteroviruses are acid stable and have a lower density.
p.29
Virus Structure and Symmetry
What is the size and shape of the virus described?
27-nm icosahedral nucleocapsid core.
p.47
Classification of Viruses
Name some human pathogens caused by arboviruses.
Dengue, yellow fever, West Nile fever, and encephalitis viruses.
p.69
Virus Structure and Symmetry
What determines the specificity of a virus for a host cell?
The specific proteins on the virus surface interact with receptors on the host cell.
p.31
Virus Structure and Symmetry
What shape are Poxviruses?
Large brick-shaped or ovoid.
p.19
Host Defenses Against Viruses
Have any specific disease associations been proven for Anelloviruses?
No specific disease associations have been proven.
p.56
DNA-Containing Virus Families
What type of RNA do retroviruses contain?
Two copies of linear, positive-sense, single-stranded RNA.
p.56
Viral Replication Cycle
What unique enzyme do retroviruses contain?
Reverse transcriptase enzyme.
p.11
Definition and Characteristics of Viruses
What does 'natural host range' refer to?
The range of hosts that a virus can infect.
p.59
Classification of Viruses
How are hantaviruses transmitted?
By persistently infected rodents via aerosols of contaminated excreta.
p.83
Definition and Characteristics of Viruses
What does the viral nucleic acid encode?
The genetic information necessary for replication of the virus.
p.103
Host Defenses Against Viruses
What is the basis for all serologically based tests?
The interaction of antigen and antibody.
p.112
Antiviral Chemotherapy and Molecular Virology
What is the function of reverse transcriptase inhibitors?
They bind directly to reverse transcriptase.
p.69
Virus Structure and Symmetry
What are the basic components of a virus?
A virus typically consists of genetic material (DNA or RNA) enclosed in a protein coat called a capsid.
p.37
RNA-Containing Virus Families
What is the relationship between rhinoviruses and acidity?
Rhinoviruses are acid labile.
p.51
Virus Structure and Symmetry
What is the size range of Arenaviruses?
60 to 300 nm, with a mean of 110 – 130 nm.
p.99
Host Defenses Against Viruses
How does IgM contribute to the evolution of the humoral response?
By aiding in the trapping of antigens for lymphocyte refinement.
p.48
Chemical Composition of Viruses
What type of genome do Togaviridae viruses possess?
Single-stranded, positive-sense RNA.
p.8
Classification of Viruses
What is one method used for classifying viruses based on their structure?
By their capsid shape (icosahedral, helical, etc.).
p.47
Classification of Viruses
What human diseases are associated with rodent-borne viruses?
Hantavirus infections and Lassa fever.
p.72
Virus Structure and Symmetry
What types of rotational symmetry axes does an icosahedron have?
Fivefold, threefold, and twofold axes of rotational symmetry.
p.32
Virus Structure and Symmetry
What type of enzymatic activity is present in poxvirus proteins?
DNA-dependent RNA polymerase.
p.39
Chemical Composition of Viruses
What type of genome do Astroviruses possess?
Linear, positive-sense, single-stranded RNA.
p.21
DNA-Containing Virus Families
What type of cancer is the Merkel cell virus associated with?
Merkel cell skin carcinomas.
p.97
Host Defenses Against Viruses
What is humoral immunity primarily mediated by?
Antibodies produced by B cells.
p.54
Classification of Viruses
What distinct genus do toroviruses belong to?
They form a distinct genus that causes gastroenteritis.
p.9
DNA-Containing Virus Families
What factors can define the segments of a virus genome?
Number and size of segments.
p.65
Classification of Viruses
Do most newly discovered viruses belong to existing families?
Yes, most belong to existing families.
p.65
Classification of Viruses
Are there any newly discovered viruses that are not classifiable?
Yes, some agents are not classifiable.
p.2
Definition and Characteristics of Viruses
How can viruses be described in relation to living cells?
As a parasite at the genetic level, replicating in living cells and inert in the extracellular environment.
p.7
Classification of Viruses
What is the primary basis for the classification of viruses?
The type of nucleic acid they contain (DNA or RNA).
p.47
Viral Replication Cycle
How does viral replication affect infected arthropods?
It does not seem to harm them.
p.46
Viral Replication Cycle
What is the role of arthropods in the life cycle of arboviruses?
They act as vectors that transmit the viruses to vertebrate hosts by their bite.
p.68
Definition and Characteristics of Viruses
What is mad cow disease?
A prion disease found in cattle.
p.28
Virus Structure and Symmetry
What type of virus are Hepadnaviruses?
Enveloped viruses containing circular DNA.
p.48
Virus Structure and Symmetry
What is a characteristic feature of Togaviridae viruses?
They have a lipid-containing envelope and are ether sensitive.
p.53
Chemical Composition of Viruses
What type of genome do coronaviruses contain?
An unsegmented genome of positive-sense, single-stranded RNA.
p.58
DNA-Containing Virus Families
What type of RNA makes up the Bunyaviridae genome?
The genome consists of triple-segmented, negative-sense or ambisense RNA.
p.66
Definition and Characteristics of Viruses
What are viroids?
Small infectious agents that cause diseases of plants.
p.19
DNA-Containing Virus Families
What is the nature of the viral genome in Anelloviruses?
Negative sense, circular, single stranded DNA.
p.97
Host Defenses Against Viruses
What are the two main types of host defenses?
Non-specific and specific defenses.
p.97
Host Defenses Against Viruses
What are examples of non-specific host defenses?
Interferons and NK (Natural Killer) cells.
p.66
RNA-Containing Virus Families
What type of RNA molecules are plant viroids?
Single-stranded, covalently closed circular RNA molecules.
p.26
Classification of Viruses
What diseases can adenoviruses cause?
Acute respiratory diseases, conjunctivitis, and gastroenteritis.
p.62
Chemical Composition of Viruses
What type of RNA do paramyxoviruses contain?
Linear, single-stranded, nonsegmented, negative-sense RNA.
p.82
Virus Structure and Symmetry
What specific activities may some surface proteins exhibit?
Some surface proteins may exhibit specific activities related to the virus's function.
p.97
Host Defenses Against Viruses
What is cell-mediated immunity primarily associated with?
T cells that directly attack infected cells.
p.11
Definition and Characteristics of Viruses
What are tissue tropisms?
The preference of a virus for specific tissues in the host.
p.65
Classification of Viruses
What is the trend regarding the discovery of novel viruses?
Novel viruses are being discovered with increasing frequency.
p.103
Host Defenses Against Viruses
What role does serology play in diagnostics?
It is an important diagnostic tool for diseases including infections and autoimmune disorders.
p.67
Definition and Characteristics of Viruses
What is unique about the infectious prion protein?
It is misfolded and can change the conformation of the native prion protein.
p.3
Virus Structure and Symmetry
What is the function of the capsid in a virus?
It encases and stabilizes viral nucleic acid and facilitates attachment and penetration into new cells.
p.3
Host Defenses Against Viruses
What can be the effects of a virus infection on the host cell?
It may have little or no effect, or it may result in cell damage or death.
p.17
DNA-Containing Virus Families
What type of genome does Human parvovirus B19 have?
Linear, single-stranded DNA.
p.84
Virus Structure and Symmetry
How do viruses acquire their lipid envelopes?
When the viral nucleocapsid buds through a cellular membrane during maturation.
p.14
DNA-Containing Virus Families
What type of genetic material do DNA-containing viruses possess?
Double-stranded or single-stranded DNA.
p.60
Virus Structure and Symmetry
What type of virus is Bornaviridae?
Enveloped, spherical viruses.
p.23
Viral Replication Cycle
Can Papillomaviruses be grown in cultured cells in vitro?
No, they cannot be grown in cultured cells in vitro.
p.82
Virus Structure and Symmetry
What role do viral proteins play in the virus's interaction with host cells?
They participate in the attachment of the virus particle to a susceptible cell.
p.66
RNA-Containing Virus Families
What is the structure of plant viroids?
They have a highly base-paired rodlike structure.
p.42
DNA-Containing Virus Families
What type of genome do hepeviruses have?
Single-stranded, positive-sense RNA.
p.54
Definition and Characteristics of Viruses
What severe illnesses are caused by new coronaviruses?
Severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).
p.56
Viral Replication Cycle
What process does reverse transcriptase perform?
It produces a DNA copy of the RNA genome.
p.11
Definition and Characteristics of Viruses
What are biological properties of viruses?
Natural host range, mode of transmission, vector relationships, pathogenicity, tissue tropisms, and pathology.
p.11
Definition and Characteristics of Viruses
What are vector relationships in virology?
The interactions between viruses and their vectors for transmission.
p.63
Classification of Viruses
Which viruses infect humans?
Mumps, measles, parainfluenza, metapneumo, and respiratory syncytial viruses.
p.105
Vaccination and Immunization
What is vaccination?
The process of getting or acquiring a vaccine.
p.83
Classification of Viruses
What are the major characteristics used for classifying viruses into families?
The type of nucleic acid, its polarity, and its size.
p.73
Virus Structure and Symmetry
Do most viruses with icosahedral symmetry have an icosahedral shape?
No, they do not have an icosahedral shape.
p.6
Virus Structure and Symmetry
What are structural units in the context of viruses?
The basic protein building blocks of the coat, usually a collection of more than one nonidentical protein subunit.
p.25
Definition and Characteristics of Viruses
What does the term 'adenovirus' derive from?
The Latin word 'adenos', meaning gland.
p.21
DNA-Containing Virus Families
What type of genome do the viruses mentioned have?
Circular, double-stranded DNA, about 5 kb in size.
p.84
Virus Structure and Symmetry
What factors influence the budding process of viruses?
The replication strategy of the virus and the structure of the nucleocapsid.
p.5
Virus Structure and Symmetry
What is an envelope in the context of viruses?
A lipid-containing membrane that surrounds some virus particles.
p.14
DNA-Containing Virus Families
What is a characteristic of the Adenoviridae family?
They are known to cause respiratory infections.
p.84
Virus Structure and Symmetry
What determines the phospholipid composition of a virion envelope?
The specific type of cell membrane involved in the budding process.
p.50
Viral Replication Cycle
Where do mature Flavivirus virions accumulate?
Within cisternae of the endoplasmic reticulum.
p.72
Virus Structure and Symmetry
How many neighbors do the vertex units of an icosahedron have?
Five neighbors (pentavalent).
p.32
Viral Replication Cycle
Where does replication of poxviruses occur?
Entirely within the cell cytoplasm.
p.14
DNA-Containing Virus Families
What is the significance of the Parvoviridae family?
They are the smallest DNA viruses and can only replicate in dividing cells.
p.42
Chemical Composition of Viruses
Are hepevirus particles ether resistant?
Yes, they are ether resistant.
p.85
Virus Structure and Symmetry
How do the lipids in viral membranes differ from viral glycoproteins?
Lipids are derived from the host cell, while sugars in glycoproteins reflect the host cell in which the virus is grown.
p.85
Virus Structure and Symmetry
What is the role of surface glycoproteins in enveloped viruses?
They attach the virus particle to a target cell by interacting with a cellular receptor.
p.11
Virus Structure and Symmetry
What physicochemical properties of the virion are important?
Molecular mass, buoyant density, pH stability, thermal stability, and susceptibility to agents.
p.56
Viral Replication Cycle
How is the virus replicated after integration?
From the integrated 'provirus' DNA copy.
p.57
DNA-Containing Virus Families
What is the range of nucleotides in the segments of the Orthomyxovirus genome?
890 to 2350 nucleotides each.
p.46
Definition and Characteristics of Viruses
What type of properties do arboviruses and rodent-borne viruses possess?
Diverse physical and chemical properties.
p.36
Chemical Composition of Viruses
Are Picornaviruses ether-resistant?
Yes, they are ether-resistant.
p.37
RNA-Containing Virus Families
What diseases do picornaviruses cause in animals?
Foot-and-mouth disease in cattle and encephalomyocarditis in rodents.
p.51
Chemical Composition of Viruses
What type of RNA do Arenaviruses possess?
Segmented, circular, single-stranded RNA that is negative sense and ambisense.
p.23
Classification of Viruses
Are Papillomaviruses host and tissue specific?
Yes, they are very host and tissue specific.
p.22
Host Defenses Against Viruses
What disease is associated with the JC virus?
Progressive multifocal leukoencephalopathy (PML).
p.42
Definition and Characteristics of Viruses
How do hepeviruses compare to caliciviruses?
Hepeviruses are similar to caliciviruses.
p.22
Host Defenses Against Viruses
Who is most at risk for JC virus infection?
Immunocompromised individuals, such as those with HIV/AIDS or undergoing immunosuppressive therapy.
p.34
Classification of Viruses
What is a unique feature of positive-sense single-stranded RNA viruses?
Their RNA can serve directly as mRNA for protein synthesis.
p.19
Classification of Viruses
Where are Anelloviruses distributed?
Globally in the human population and many animal species.
p.39
Host Defenses Against Viruses
What health issues are Astroviruses associated with?
Gastroenteritis in humans and animals.
p.31
Definition and Characteristics of Viruses
What does the name 'Poxviridae' derive from?
The Anglo-Saxon word 'pokkes' meaning pouch, referring to their characteristic vesicular skin lesions.
p.85
Chemical Composition of Viruses
Why are glycoproteins important for viruses?
They are important viral antigens.
p.56
Viral Replication Cycle
What happens to the DNA after it is produced from the RNA genome?
It becomes circularized and integrated into host chromosomal DNA.
p.9
DNA-Containing Virus Families
What is meant by 'percent GC content' in a virus genome?
The percentage of guanine and cytosine nucleotides in the genome.
p.68
Definition and Characteristics of Viruses
What human diseases are classified as prion diseases?
Kuru and Creutzfeldt-Jakob disease.
p.28
Viral Replication Cycle
What are the key steps involved in the replication of Hepadnaviruses?
Repair of the single-stranded gap in DNA, transcription of RNA, and reverse transcription of RNA to make genomic DNA.
p.69
Virus Structure and Symmetry
How does the structure of viruses vary?
Viruses can have various shapes, including helical, icosahedral, and complex structures.
p.96
Host Defenses Against Viruses
What are physical barriers in host defenses?
Anatomical features like skin and mucous membranes that prevent virus entry.
p.64
Chemical Composition of Viruses
What is the genome type of Filoviruses?
Linear, negative-sense, single-stranded RNA.
p.72
Virus Structure and Symmetry
How many faces does an icosahedron have?
20 faces, each an equilateral triangle.
p.76
Virus Structure and Symmetry
How are the nucleocapsids of most helical animal viruses characterized?
They are flexible and wound into a ball inside envelopes.
p.34
Viral Replication Cycle
How do RNA-containing viruses replicate their genetic material?
Using RNA-dependent RNA polymerase.
p.60
Chemical Composition of Viruses
What type of genome do Bornaviruses have?
Linear, single-stranded, nonsegmented, negative-sense RNA.
p.64
Definition and Characteristics of Viruses
What diseases do Marburg and Ebola viruses cause?
Severe hemorrhagic fever.
p.47
Classification of Viruses
Which virus families do the mentioned viruses belong to?
Arenaviridae, bunyaviridae, flaviviridae, reoviridae, rhabdoviridae, and togaviridae.
p.50
Classification of Viruses
Which viruses are included in the Flavivirus group?
Yellow fever virus and dengue viruses.
p.20
Chemical Composition of Viruses
What resistance do Polyomaviruses exhibit?
Solubilization-resistant.
p.22
Host Defenses Against Viruses
What is the typical outcome of a JC virus infection in healthy individuals?
Most healthy individuals remain asymptomatic and do not develop PML.
p.66
Viral Replication Cycle
How do viroids replicate?
By an entirely novel mechanism.
p.54
Definition and Characteristics of Viruses
What illnesses do most human coronaviruses cause?
Mild acute upper respiratory tract illnesses, commonly known as 'colds'.
p.54
Classification of Viruses
Which animal coronaviruses are known to establish persistent infections?
Mouse hepatitis virus and avian infectious bronchitis virus.
p.7
Classification of Viruses
What role does the host range play in virus classification?
It helps determine the types of cells a virus can infect.
p.6
Virus Structure and Symmetry
What is a virion?
The complete virus particle.
p.49
Classification of Viruses
Does the rubella virus have an arthropod vector?
No, it has no arthropod vector.
p.82
Virus Structure and Symmetry
What is the major purpose of viral structural proteins?
To facilitate the transfer of viral nucleic acid from one host cell to another.
p.62
Virus Structure and Symmetry
How do paramyxoviruses compare in size to orthomyxoviruses?
Paramyxoviruses are larger, measuring 150 – 300 nm.
p.29
Viral Replication Cycle
What happens to the surface protein during viral replication?
It is characteristically overproduced and shed into the bloodstream.
p.58
Virus Structure and Symmetry
What do virion particles of Bunyaviruses contain?
Three circular, helically symmetric nucleocapsids about 2.5 nm in diameter and 200 to 3000 nm in length.
p.20
Definition and Characteristics of Viruses
What do the Greek roots 'poly-' and '-oma' in Polyomavirus mean?
'Poly-' means many, and '-oma' refers to tumor.
p.58
Viral Replication Cycle
Where does replication of Bunyaviruses occur?
Replication occurs in the cytoplasm.
p.72
Virus Structure and Symmetry
How many neighbors do the other units of an icosahedron have?
Six neighbors (hexavalent).
p.34
Classification of Viruses
What is a characteristic of negative-sense single-stranded RNA viruses?
They must be converted to a positive-sense RNA before translation.
p.31
Virus Structure and Symmetry
What is unique about the particle structure of Poxviruses?
It is complex and contains a lipid-containing envelope.
p.61
Virus Structure and Symmetry
What shape do Rhabdoviruses resemble?
A bullet, flat at one end and round at the other.
p.56
Virus Structure and Symmetry
What type of nucleocapsid do retroviruses have?
A helical nucleocapsid within an icosahedral capsid.
p.11
Definition and Characteristics of Viruses
What is meant by 'mode of transmission' in the context of viruses?
The method by which a virus spreads from one host to another.
p.107
Vaccination and Immunization
How many doses are typically needed for immunity with attenuated live vaccines?
1 dose for immunity; 2 doses to ensure seroconversion.
p.8
Classification of Viruses
What role do host organisms play in virus classification?
Viruses can be classified based on the type of host they infect (e.g., animal, plant, or bacterial viruses).
p.43
DNA-Containing Virus Families
What type of genome do Picobirnaviruses have?
Linear, double-stranded, segmented RNA.
p.107
Vaccination and Immunization
Can you name some examples of live vaccines?
MMR, Rotavirus, Influenza.
p.21
DNA-Containing Virus Families
What is a characteristic of the growth cycle of these viruses?
They have a slow growth cycle.
p.47
Classification of Viruses
What are rodent-borne viruses known for?
Establishing persistent infections in rodents and being transmitted without an arthropod vector.
p.22
Definition and Characteristics of Viruses
What is the JC virus?
A polyomavirus that can cause progressive multifocal leukoencephalopathy (PML) in immunocompromised individuals.
p.20
Definition and Characteristics of Viruses
What does the name 'Polyomavirus' refer to?
The ability of some of these viruses to produce tumors in infected hosts.
p.53
Virus Structure and Symmetry
What unique feature do coronaviruses have on their surface?
Petal-shaped surface projections arranged in a fringe, similar to a solar corona.
p.21
DNA-Containing Virus Families
What condition is associated with the BK virus?
Nephropathy in transplant recipients.
p.97
Host Defenses Against Viruses
What are the two subtypes of specific host defenses?
Humoral and cell-mediated defenses.
p.22
Definition and Characteristics of Viruses
How is the JC virus transmitted?
Primarily through respiratory secretions or urine.
p.97
Host Defenses Against Viruses
What role do interferons play in host defense?
They help inhibit viral replication and activate immune responses.
p.60
Host Defenses Against Viruses
Is there a proven association between Borna disease virus and human neuropsychiatric disorders?
No, the association is unproven.
p.44
Virus Structure and Symmetry
How many protein shells do Reovirus particles have?
Two or three protein shells.
p.9
DNA-Containing Virus Families
What are the properties of a virus genome?
Type of nucleic acid, size, strandedness, linear or circular form, sense, segments, nucleotide sequence, percent GC content, and presence of special features.
p.11
Definition and Characteristics of Viruses
What does pathogenicity mean in relation to viruses?
The ability of a virus to cause disease.
p.58
Virus Structure and Symmetry
What is the shape and structure of Bunyaviruses?
Bunyaviruses are spherical or pleomorphic, enveloped particles measuring 80 to 120 nm.
p.36
RNA-Containing Virus Families
What type of RNA genome do Picornaviruses have?
Single stranded and positive sense.
p.53
Virus Structure and Symmetry
How do coronaviruses resemble orthomyxoviruses?
In structure, but coronaviruses have petal-shaped surface projections.
p.96
Host Defenses Against Viruses
What is the role of antibodies in viral defense?
Antibodies bind to viruses, neutralizing them and marking them for destruction by immune cells.
p.82
Virus Structure and Symmetry
What aspect of viruses do proteins provide?
Structural symmetry of the virus particle.
p.56
Classification of Viruses
What type of virus is L. Retroviridae?
Retroviruses are spherical, enveloped viruses.
p.16
Definition and Characteristics of Viruses
What does the term 'Parvoviridae' refer to?
A family of small viruses known as parvoviruses.
p.34
Host Defenses Against Viruses
What role do RNA viruses play in human health?
They can cause various diseases, including respiratory infections and hepatitis.
p.44
DNA-Containing Virus Families
What is the structure of the Reovirus genome?
Linear, double-stranded, segmented RNA (10 – 12 segments).
p.16
Virus Structure and Symmetry
Do parvoviruses have an envelope?
No, they do not have an envelope.
p.11
Virus Structure and Symmetry
What factors influence the physicochemical stability of a virion?
Molecular mass, buoyant density, pH stability, thermal stability, and susceptibility to solubilizing agents.
p.9
RNA-Containing Virus Families
What does the term 'sense' refer to in viral genomes?
It refers to whether the genome is positive, negative, or ambisense.
p.9
Virus Structure and Symmetry
What are peplomers in the context of virion morphology?
They are spike-like structures on the virus surface.
p.96
Host Defenses Against Viruses
How do interferons contribute to host defenses?
Interferons are proteins produced by infected cells that help inhibit viral replication and activate immune cells.
p.81
Chemical Composition of Viruses
What types of nucleic acids can viruses contain?
Viruses can contain either DNA or RNA, which can be single-stranded or double-stranded.
p.40
Chemical Composition of Viruses
What type of genome do caliciviruses possess?
Single-stranded, positive-sense RNA.
p.66
Definition and Characteristics of Viruses
How do viroids differ from classic viruses?
Viroids are nucleic acid molecules without a protein coat.
p.96
Host Defenses Against Viruses
What is the significance of cellular immunity in combating viruses?
Cellular immunity involves T cells that recognize and destroy virus-infected cells.
p.44
Definition and Characteristics of Viruses
What is the size range of Reoviruses?
Medium-sized (60 – 80 nm).
p.52
Classification of Viruses
What kind of laboratory conditions are required for working with arenaviruses?
Maximum containment conditions.
p.31
Virus Structure and Symmetry
What are the dimensions of Poxviruses?
220 – 450 nm long × 140 – 260 nm wide × 140 – 260 nm thick.
p.82
Host Defenses Against Viruses
What does the host's immune response target on the virus?
Antigenic determinants of proteins or glycoproteins exposed on the surface of the virus particle.
p.85
Viral Replication Cycle
What additional role do glycoproteins play during viral infection?
They are often involved in the membrane fusion step of infection.
p.57
DNA-Containing Virus Families
What type of genome do Orthomyxoviruses have?
Linear, segmented, negative-sense, single-stranded RNA.
p.40
Virus Structure and Symmetry
What characteristic feature do calicivirus particles have?
They appear to have cup-shaped depressions on their surfaces.
p.21
DNA-Containing Virus Families
What disease is caused by the JC virus?
Progressive multifocal leukoencephalopathy.
p.25
Virus Structure and Symmetry
What aids adenoviruses in host attachment?
Fiber spikes protruding from capsomers.
p.52
Classification of Viruses
What is an example of an arenavirus that causes disease in humans?
Lassa fever virus of Africa.
p.96
Host Defenses Against Viruses
How do vaccines enhance host defenses against viruses?
Vaccines stimulate the immune system to recognize and respond more effectively to specific viruses.
p.40
Classification of Viruses
What are important human pathogens in the Caliciviridae family?
Noroviruses, such as Norwalk virus.
p.97
Host Defenses Against Viruses
What is the function of NK cells in the immune system?
They attack and destroy infected or cancerous cells.
p.42
Chemical Composition of Viruses
What protein is lacking in the hepevirus genome?
Genome-linked protein (VPg).
p.9
DNA-Containing Virus Families
What does strandedness refer to in a virus genome?
Whether the nucleic acid is single or double stranded.
p.57
Classification of Viruses
Name one genus from the Orthomyxoviridae family.
Alphainfluenzavirus, Betainfluenzavirus, Gammainfluenzavirus, Deltainfluenzavirus, Isavirus, Thogotovirus, or Quaranjavirus.
p.29
Host Defenses Against Viruses
What is the risk associated with persistent Hepatitis B infections?
A high risk of developing liver cancer.
p.58
Viral Replication Cycle
How do Bunyaviruses acquire their envelope?
By budding into the Golgi.
p.54
Viral Replication Cycle
How do coronavirus nucleocapsids mature?
By budding into cytoplasmic vesicles.
p.61
Chemical Composition of Viruses
What type of RNA is the genome of Rhabdoviruses?
Linear, single-stranded, nonsegmented, negative-sense RNA.
p.56
Viral Replication Cycle
How does virion assembly occur in retroviruses?
By budding on plasma membranes.
p.50
Host Defenses Against Viruses
How are most Flavivirus members transmitted?
By blood-sucking arthropods.
p.40
Host Defenses Against Viruses
What illness do noroviruses cause?
Epidemic acute gastroenteritis.
p.9
Virus Structure and Symmetry
What are the key aspects of virion morphology?
Size, shape, type of symmetry, presence or absence of peplomers, and presence or absence of membranes.
p.11
Definition and Characteristics of Viruses
What are antigenic properties in viruses?
Reactions to various antisera.
p.57
Virus Structure and Symmetry
What activities do the surface projections of Orthomyxoviruses contain?
Hemagglutinin or neuraminidase activity.
