46 Questions
What is the primary characteristic that defines a virus as an obligate intracellular parasite?
They require host cell metabolic processes and protein synthesis machinery.
What is the typical size range of the RNA or DNA genome in a virus?
20-300 nm
What is unique about the structure of viruses?
They have a diverse range of structures, including icosahedral, helical, and others.
Where can a virus replicate in a host cell?
In the cytoplasm, the nucleus, or both
What is the size range of human viral pathogens?
20-450 nm
What was the first identified virus?
Tobacco mosaic virus
What is the range of pathogenesis of viruses?
Asymptomatic infections to acute death
What is the primary function of the capsid in a virus?
To protect the genome from environmental variations
What is the term for a single virus particle?
Virion
What type of viral genome is the same as messenger RNA (mRNA)?
Positive sense (+) RNA
What is the term for the process of converting RNA into DNA during a virus's life cycle?
Reverse transcription
What is the main advantage of a viral envelope?
It protects the virus from chemicals and enzymes
What is the purpose of the matrix in a virus?
To associate with the virion membrane
Why do most viruses have a specific host, tissue, or cell type?
Because they require specific cellular pathways
What is the term for the classification of viruses based on their nucleic acid type and replication?
Baltimore classification
What is the term for the shape of a virus with 20 triangular faces and 12 vertices?
Icosahedron
What is a characteristic of DNA viruses that distinguishes them from RNA viruses?
They carry enzymes to increase dNTP pools
Which of the following viruses is limited to infecting mitotically active cells?
Parvovirus
What is the primary site of assembly for enveloped DNA viruses?
Plasma membrane
What is the term for diseases that are naturally transmitted between humans and other vertebrates?
Zoonoses
Which of the following transmission routes is dependent on the stability of the virus in environmental conditions?
Fomites
What is the term for the period between exposure and the onset of symptoms in a viral disease?
Incubation period
Which of the following is an example of a transmission factor that enhances the transmission of a virus?
School holidays
What is the term for the process by which viruses assemble capsids and inject their genome into a host cell?
Assembly
Which of the following is an example of a virus that usurps the ESCRT vesicular budding pathway?
HIV-1
What is the term for the cells that are targeted by a virus and result in clinical disease?
Target cells
What is the primary factor that determines the absolute measurement of a virus's host range?
Availability of host cell receptors for virus binding
Which of the following is an example of a non-epithelial site where viral infections can initiate?
Skin
What is the result of receptor binding during virus fusion and entry?
Conformation change in envelope protein and fusion with cell membrane
What is the mechanism of endocytosis involved in virus fusion and entry?
Receptor-mediated endocytosis
What is the role of dsRNA in RNA virus replication?
It is an intermediate in RNA replication
What is the purpose of membranous replication complexes in RNA virus replication?
To sequester viral components and protect against innate immunity
What is the limitation of RNA virus genome size?
Maximum of 30,000 nucleotides
What is the mechanism used by RNA viruses to increase genetic capacity?
All of the above
Where does DNA virus replication typically occur?
In the nucleus
What is the role of origin-binding proteins in DNA virus replication?
To bind to the origin of replication
What is the result of the host immune response being stronger than the virus?
Resolution of the infection
What is the typical outcome of most viral infections?
No disease
Which type of viral infection involves an initial acute phase, followed by apparent recovery, and then a secondary disease phase?
Biphasic disease
What is the term for the ability of a virus to establish a long-term infection that can last for many years or a lifetime?
Persistence
Which type of viral infection involves the virus entering a dormant phase, with no symptoms, and can reactivate to cause recurrent infections?
Latent infection
What is the term for the process by which a virus promotes cell growth and survival, leading to an increased tolerance for DNA mutations and ultimately cellular transformation?
Neoplastic transformation
Which type of diagnostic test involves the detection of viral nucleic acids in blood, mucus, excretion, or tissue samples?
PCR or RT-PCR
What is the primary target for the treatment of viral diseases?
Unique viral enzymes
What is the term for the type of vaccine that safely induces an immune response capable of preventing or attenuating illness?
Prophylactic vaccine
What is the purpose of a therapeutic vaccine?
To boost the immune response to reduce pathology
This quiz covers the general principles of virology, including the introduction to viruses, their classification, structural principles, and replication mechanisms. It also touches on medical conditions caused by viral diseases and their treatments. The quiz focuses on both DNA and RNA viruses, including Pox, Herpes, Hepadna, and Corona viruses.
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