This set of Virology Multiple Choice Questions & Answers (MCQs) focuses on “Humans Viruses – Retroviridae and Hepadnaviridae”.
1. Who described the first human retrovirus?
a) Peyton Rous
b) Bob Gallo
c) Temin
d) Baltimore
View Answer
Explanation: Bob Gallo and his colleagues in the year 1980 described the first human retroviruses which caused the adult T cell leukemia. Gallo was also instrumental in confirming and extending the discovery by Luc Montagnier.
2. The virions of retrovirus are ___________
a) conical
b) rod-shaped
c) spherical
d) rhombical
View Answer
Explanation: The virions of retroviruses are spherical with 80 – 100 nm in diameter and have a unique three-layered structure. The structure is enclosed within a capsid and appears icosahedral.
3. Which of the following gene activates the expression of all of its genes as well as certain cellular genes?
a) gag
b) pol
c) env
d) lax
View Answer
Explanation: Lax is the regulatory gene, present in HTLV-1, that transactivates the expression of all its genes as well as certain cellular genes. The HTLV-1 is the only human retrovirus that does not contain any oncogenes.
4. Which of the following is the demyelination of the long motor neuron tracts in the spinal cord?
a) TSP
b) ATL
c) AIDS
d) Cancer
View Answer
Explanation: Tropical spastic paraparesis (TSP) is progressive demyelination of the long motor neuron tracts in the spinal cord. It is also known as HTLV-1 associated myelopathy that is mainly seen in 20 to 50-year-old women.
5. Which of the following causes AIDS in rhesus monkeys?
a) HIV
b) Spumavirus
c) SIV
d) DIV
View Answer
Explanation: Simian Immunodeficiency Virus (SIV) causes AIDS in rhesus (Asian) monkeys. The SIV belongs to the lentivirus genera and may occasionally infect humans but there no indication of SIV causing disease in humans.
6. The Human Spumavirus contains oncogene.
a) True
b) False
View Answer
Explanation: The Human Spumavirus is the exogenous retroviruses that do not contain oncogenes. They comprise a group of “foamy virus” that cause inapparent persistent infections but have not yet been proved to cause any disease.
7. The genome of Hepadnavirus is _______________
a) circular dsDNA
b) linear dsDNA
c) circular ssDNA
d) linear ssDNA
View Answer
Explanation: The genome of Hepadnavirus is a circular double-stranded DNA of the size 3.2 kilobase pairs. It consists of plus and minus strands in which plus strand is incomplete and minus strand is complete but contains discontinuity (nicks) at a unique site.
8. Which of the following is also known as Deltavirus?
a) Hepatitis B
b) Hepatitis A
c) Hepatitis C
d) Hepatitis D
View Answer
Explanation: Hepatitis D is also known as Deltavirus and is unique among human viruses and some regard it as a subviral agent falling outside the definition of a virus. It consists of single-stranded RNA as its genome.
9. Who detected the novel antigen delta?
a) Rizzetto
b) Watson
c) Franklin
d) Crick
View Answer
Explanation: Rizzetto in the year 1977 detected a novel antigen delta in the nuclei of hepatocytes from the severe cases of hepatitis B. The delta agent is now known as the hepatitis D virus, is a defective satellite virus that is found only in the association with HBV helper virus.
10. The virion of Deltavirus is heterogeneous.
a) True
b) False
View Answer
Explanation: The virion of Deltavirus or HDV is heterogeneous in size (30 – 40 nm) and roughly spherical. The coat of the virion is composed of HBsAg, mainly lacking the pre-S regions.
Sanfoundry Global Education & Learning Series – Virology.
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