MIC541: Virology Section by Michael Belshan

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What is the primary characteristic that defines a virus as an obligate intracellular parasite?

They can only infect eukaryotic cells.

They require host cell metabolic processes and protein synthesis machinery. (correct)

They have a cell wall similar to bacteria.

They can replicate outside of a host cell.

What is the typical size range of the RNA or DNA genome in a virus?

300-500 nm

20-300 nm (correct)

2-10 nm

10-20 nm

What is unique about the structure of viruses?

They all have a icosahedral structure.

They all have a helical structure.

They have a diverse range of structures, including icosahedral, helical, and others. (correct)

They all have a cell wall similar to bacteria.

Where can a virus replicate in a host cell?

In the cytoplasm, the nucleus, or both Signup and view all the answers

What is the size range of human viral pathogens?

20-450 nm Signup and view all the answers

What was the first identified virus?

Tobacco mosaic virus Signup and view all the answers

What is the range of pathogenesis of viruses?

Asymptomatic infections to acute death Signup and view all the answers

What is the primary function of the capsid in a virus?

To protect the genome from environmental variations Signup and view all the answers

What is the term for a single virus particle?

Virion Signup and view all the answers

What type of viral genome is the same as messenger RNA (mRNA)?

Positive sense (+) RNA Signup and view all the answers

What is the term for the process of converting RNA into DNA during a virus's life cycle?

Reverse transcription Signup and view all the answers

What is the main advantage of a viral envelope?

It protects the virus from chemicals and enzymes Signup and view all the answers

What is the purpose of the matrix in a virus?

To associate with the virion membrane Signup and view all the answers

Why do most viruses have a specific host, tissue, or cell type?

Because they require specific cellular pathways Signup and view all the answers

What is the term for the classification of viruses based on their nucleic acid type and replication?

Baltimore classification Signup and view all the answers

What is the term for the shape of a virus with 20 triangular faces and 12 vertices?

Icosahedron Signup and view all the answers

What is a characteristic of DNA viruses that distinguishes them from RNA viruses?

They carry enzymes to increase dNTP pools Signup and view all the answers

Which of the following viruses is limited to infecting mitotically active cells?

Parvovirus Signup and view all the answers

What is the primary site of assembly for enveloped DNA viruses?

Plasma membrane Signup and view all the answers

What is the term for diseases that are naturally transmitted between humans and other vertebrates?

Zoonoses Signup and view all the answers

Which of the following transmission routes is dependent on the stability of the virus in environmental conditions?

Fomites Signup and view all the answers

What is the term for the period between exposure and the onset of symptoms in a viral disease?

Incubation period Signup and view all the answers

Which of the following is an example of a transmission factor that enhances the transmission of a virus?

School holidays Signup and view all the answers

What is the term for the process by which viruses assemble capsids and inject their genome into a host cell?

Assembly Signup and view all the answers

Which of the following is an example of a virus that usurps the ESCRT vesicular budding pathway?

HIV-1 Signup and view all the answers

What is the term for the cells that are targeted by a virus and result in clinical disease?

Target cells Signup and view all the answers

What is the primary factor that determines the absolute measurement of a virus's host range?

Availability of host cell receptors for virus binding Signup and view all the answers

Which of the following is an example of a non-epithelial site where viral infections can initiate?

Skin Signup and view all the answers

What is the result of receptor binding during virus fusion and entry?

Conformation change in envelope protein and fusion with cell membrane Signup and view all the answers

What is the mechanism of endocytosis involved in virus fusion and entry?

Receptor-mediated endocytosis Signup and view all the answers

What is the role of dsRNA in RNA virus replication?

It is an intermediate in RNA replication Signup and view all the answers

What is the purpose of membranous replication complexes in RNA virus replication?

To sequester viral components and protect against innate immunity Signup and view all the answers

What is the limitation of RNA virus genome size?

Maximum of 30,000 nucleotides Signup and view all the answers

What is the mechanism used by RNA viruses to increase genetic capacity?

All of the above Signup and view all the answers

Where does DNA virus replication typically occur?

In the nucleus Signup and view all the answers

What is the role of origin-binding proteins in DNA virus replication?

To bind to the origin of replication Signup and view all the answers

What is the result of the host immune response being stronger than the virus?

Resolution of the infection Signup and view all the answers

What is the typical outcome of most viral infections?

No disease Signup and view all the answers

Which type of viral infection involves an initial acute phase, followed by apparent recovery, and then a secondary disease phase?

Biphasic disease Signup and view all the answers

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 Signup and view all the answers

Which type of viral infection involves the virus entering a dormant phase, with no symptoms, and can reactivate to cause recurrent infections?

Latent infection Signup and view all the answers

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 Signup and view all the answers

Which type of diagnostic test involves the detection of viral nucleic acids in blood, mucus, excretion, or tissue samples?

PCR or RT-PCR Signup and view all the answers

What is the primary target for the treatment of viral diseases?

Unique viral enzymes Signup and view all the answers

What is the term for the type of vaccine that safely induces an immune response capable of preventing or attenuating illness?

Prophylactic vaccine Signup and view all the answers

What is the purpose of a therapeutic vaccine?

To boost the immune response to reduce pathology Signup and view all the answers