1.UL37x1 is a protein encoded by ________________
a) Cytomegalovirus
b) HSV
c) SV40
d) HIV
Explanation: UL37x1 is a protein encoded by human cytomegalovirus which is a herpes virus. The protein inhibits the apoptosis of infected cells, which permits the virus to establish a long-lasting infection.
2. In which of the following infection no infectious progeny is produced?
a) Latent
b) Abortive
c) Persistent
d) Null
Explanation: The term latent is defined as existing but not exhibited. In terms of the virus-infected cell, it means that the viral genome is present but no infectious progeny is produced. Adeno-associated virus, herpesvirus exhibits latency.
3. Which of the following infection causes a change in the properties of the cell?
a) Latent
b) Abortive
c) Transforming
d) Null
Explanation: The infection of a cell with a variety of DNA viruses results in the change in a wide variety of properties of the cell and the cells may undergo rapid multiplication. This results in the transformation of cells and hence transforming infection.
4. Which infection causes a reduction in the total yield of virus particles?
a) Null
b) Transforming
c) Abortive
d) Cytopathogenic
Explanation: Abortive infection causes a reduction in the total yield of virus particles (sometimes to zero). The quality of the progeny, if produced, maybe deficient as the cells do not replicate that virus with equal efficiency.
5.In which of the following infection the cells do not have the appropriate receptor for the virus?
a) Null
b) Transforming
c) Abortive
d) Cytopathogenic
Explanation: Null infection represents the cells which do not have appropriate receptors for a particular virus, and thus cannot interact with virus particle. The viral genome is artificially introduced into such cells in the laboratory to produce progenies.
6. Apoptosis regulates cell numbers.
a) True
b) False
Explanation: Apoptosis is the process that regulates cell numbers during development. The unique feature of apoptosis is that the dying cell remains intact and its contents stay within the plasma membrane.
7. The gene bcl-2 prevents apoptosis in normal cells.
a) True
b) False
Explanation: The host cell gene bcl-2 prevents apoptosis in normal cells. This gene is responsible for preventing apoptosis in normal cells. Sindbis virus prevents the normal apoptotic response of the cell to infection by stimulating bcl-2 gene.
8. Which of the following is not the part of Koch’s postulate?
a) The microorganism is always found in diseased animals
b) The microorganism secretes toxin in culture
c) The microorganism is never found in healthy animals
d) The microorganism causes disease in healthy animals
Explanation: Koch’s postulate includes that the suspected agent must be present in a particular tissue in every case of the disease, the agent must be isolated and grown in pure culture, and pure preparations of agent must cause the same disease when they are introduced into healthy subjects.
9. Which of the following is not the criteria for the classification of virus-host interactions?
a) Production of infectious progeny
b) Size of the virus
c) Signs and symptoms
d) Duration of infection
Explanation: The categories of virus-host interaction are distinguished on four criteria: the production of infectious progeny, whether or not the virus kills its host cell, if there are observable signs and symptoms, and the duration of infection.
10. Which of the following infection is specific to only cell and not the whole organism?
a) Null
b) Subclinical
c) Chronic
d) Tumorigenic
Explanation: Null infection is an infection that occurs at the cell level. Acute, subclinical, persistent, chronic, latent, and tumorigenic are the types of infection that occur at the whole organism level.