Propagation of Viruses

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When is antiviral therapy used?

When vaccines are highly effective
When the virus is not constantly changing
When the patient has a normal immune system
When vaccines are not available or not highly effective (correct)

Who needs to be treated with antiviral agents?

Patients with a normal immune system
Patients who have been vaccinated
Patients with a weak immune system (correct)
Patients who are not infected with the virus

What is the mechanism of action of nucleoside and nucleotide analogs?

They inhibit cellular enzymes (correct)
They enhance the body's immune system
They stimulate the production of interferons
They activate the virus's own enzymes

What is the difference between nucleoside and nucleotide analogs?

Nucleotide analogs have an attached phosphate group (B) Signup and view all the answers

What is the advantage of using combinations of antiviral drugs?

It delays the emergence of resistant viruses (B) Signup and view all the answers

What is the characteristic of reverse transcriptase inhibitors?

They do not require phosphorylation for activity (D) Signup and view all the answers

What is the mechanism of action of Protease Inhibitors?

Preventing mature virion core formation (A) Signup and view all the answers

What is the function of Fuzeon?

Blocking the virus and cellular membrane fusion (D) Signup and view all the answers

Which type of viruses are stronger inducers of interferons?

RNA viruses (C) Signup and view all the answers

What is the primary role of interferons in the host cell?

To inhibit viral replication (C) Signup and view all the answers

What is the purpose of growing viruses in animals?

To study viral oncogenesis, diagnose viral infections, and for research (D) Signup and view all the answers

What is the effect of Protease Inhibitors on virus particles?

It yields non-infectious virus particles (B) Signup and view all the answers

Which of the following cell cultures is capable of undergoing an infinite number of passages?

Continuous cell lines (B) Signup and view all the answers

What is the term for the process of viral detection that involves the adsorption of erythrocytes to infected cells?

Hemadsorption (C) Signup and view all the answers

What is the primary reason for choosing a particular type of cell culture for viral cultivation?

Sensitivity of the cells to the particular virus (A) Signup and view all the answers

What is the typical lifespan of diploid cells in culture?

Up to 50 passages (D) Signup and view all the answers

What is an example of a viral cytopathological effect?

Giant cell formation (D) Signup and view all the answers

In which of the following systems are viruses typically propagated in vivo?

Chickens and mice (A) Signup and view all the answers

What is the mechanism of recombinant formation in RNA viruses with segmented genomes?

Reassortment of individual genome fragments (A) Signup and view all the answers

What is the role of a helper virus in defective interfering virus particles?

To provide essential segments of the genome for replication (D) Signup and view all the answers

What is the outcome of phenotypic mixing between different viruses?

A virus with a completely heterologous protein coat (A) Signup and view all the answers

What is the characteristic of defective interfering virus particles?

They have lost essential segments of the genome but contain normal capsid proteins (B) Signup and view all the answers

When can phenotypic mixing occur between viruses?

Between different members of the same virus family or between enveloped viruses (D) Signup and view all the answers

What is the effect of defective interfering virus particles on the homologous virus?

They interfere with the multiplication of the homologous virus (A) Signup and view all the answers

What occurs when there is a major change in the genome of the virus?

Antigenic shift (A) Signup and view all the answers

In which part of the cell are inclusion bodies found in herpes virus?

Nucleus (B) Signup and view all the answers

What is the result of the recombination of two genetically distinct viruses?

Progeny similar to itself upon replication (A) Signup and view all the answers

What is the effect of antigenic drift on the virus?

Most of the point mutations are silent (D) Signup and view all the answers

What is the characteristic of cell surface changes during viral infection?

It involves the expression of viral antigens (A) Signup and view all the answers

What is the significance of hemadsorption in viral infection?

It is a way to detect viral antigen expression (B) Signup and view all the answers

What is the primary mechanism of recombinant formation in RNA viruses with non-segmented genomes?

Actual crossover event (B) Signup and view all the answers

What is the result of a defective interfering virus particle infecting a cell without a helper virus?

The cell will undergo lysis (A) Signup and view all the answers

What is the term for the process by which the genome of one virus becomes randomly incorporated within the capsid proteins of another virus?

Phenotypic mixing (A) Signup and view all the answers

What is the outcome of phenotypic mixing between two enveloped viruses that are not closely related?

Phenotypic masking (C) Signup and view all the answers

What is the primary function of a helper virus in defective interfering virus particles?

To provide essential segments of the genome (C) Signup and view all the answers

What is the characteristic of RNA viruses with segmented genomes?

They form recombinants through reassortment of individual genome fragments (D) Signup and view all the answers

What is the result of complementation between two defective viruses?

The restoration of viral function (D) Signup and view all the answers

What is the primary difference between reassortment and phenotypic mixing?

Reassortment results in a recombinant genome, while phenotypic mixing results in a heterologous phenotype (B) Signup and view all the answers

What is the characteristic of phenotypic mixing between different members of the same virus family genotype?

It occurs with a heterologous phenotype (B) Signup and view all the answers

What is the primary difference between defective interfering virus particles and infectious viruses?

Defective viruses have lost essential segments of the genome (A) Signup and view all the answers