250+ TOP MCQs on Influenza and Parainfluenza Viruses and Answers

Virology Question Paper focuses on “Influenza and Parainfluenza Viruses”.

1. Influenza virus belongs to the family _____________
a) Papoviridae
b) Orthomyxoviridae
c) Parvoviridae
d) Retroviridae

Answer: b
Clarification: Influenza virus belongs to the family Orthomyxoviridae and the disease influenza is caused by the influenza virus. The symptoms include cough, sneezing, nasal congestion, fever, headache, etc.

2. The variation of which of the following causes influenza despite vaccines available?
a) Hemagglutinin
b) Hyaluronidase
c) Pepsin
d) Elastase

Answer: a
Clarification: The variation of the hemagglutinin (HA) and neuraminidase (NA) envelope proteins of virus causes influenza despite the vaccines like inactivated virus vaccines available. The variation allows the virus to escape neutralization.

3. Influenza viruses of human are spread by _______________
a) saliva
b) sneezing
c) fecal water
d) sexual transmission

Answer: b
Clarification: The influenza viruses of humans are spread or transmitted by aerosols that include sneezing. The replication of virus occurs in the upper and lower respiratory tract and reaches a peak after 2-3 days after infection. The influenza viruses of birds are spread by fecal contamination of water and also by aerosols.

4. From which of the following the first influenza virus isolated?
a) Human
b) Cat
c) Pig
d) Dog

Answer: c
Clarification: The first influenza virus was isolated from pigs in the year 1930. The first human influenza virus was isolated in 1933 and it was called influenza A virus whereas influenza B was isolated in 1940 and influenza C in 1946.

5. Influenza B viruses infects only _______________
a) avian species
b) humans
c) horses
d) swine

Answer: b
Clarification: Influenza B viruses appear to naturally infect only humans. Whereas influenza A viruses infect a wide variety of avian species, humans, horses and swine, and influenza C has been isolated mainly from humans and swine.

6. Which of the following influenza virus contain seven RNA segments?
a) Influenza A
b) Influenza B
c) Influenza C
d) Influenza D

Answer: c
Clarification: Influenza C virus contains seven segments of RNA whereas influenza A and B viruses contain eight distinct segments of RNA. Influenza A, B and C viruses possess similar proteins but each of the viruses has different distinct mechanisms for encoding proteins.

7. Which of the following was the first parainfluenza virus isolated?
a) Sendai virus
b) PIV-1
c) Simian virus
d) PIV-4

Answer: a
Clarification: Sendai virus was the first parainfluenza virus isolated and is a natural pathogen of mice and is antigenically similar to human PIV-1. It was previously known as the murine parainfluenza virus type 1or hemagglutinin virus of Japan (HVJ).

8. Which of the following protein mediates the fusion of virion and host-cell surface membranes?
a) M
b) S
c) F
d) HN

Answer: c
Clarification: F protein is a surface glycoprotein that mediates the fusion of virion and host-cell surface membrane. F is expressed on the surface of infected cells and allows the extension of infection to uninfected cells.

9. Which of the following protein initiates the process of infection?
a) HN
b) M
c) F
d) S

Answer: a
Clarification: The hemagglutinin-neuraminidase (HN) glycoprotein initiates the process of infection which binds the virion to the sialic acid-containing receptor on the host cell surface. It also causes the enzymatic cleavage of sialic acid residues.

10. The F proteins are synthesized as active precursors.
a) True
b) False

Answer: b
Clarification: The F proteins are synthesized as inactive precursors FO. These inactive precursors are cleaved by a host cell trypsin-like protease to form the biologically active molecule.

11. The human parainfluenza viruses are communicable.
a) True
b) False

Answer: a
Clarification: The human parainfluenza viruses (hPIV) are highly communicable. They may be transmitted by respiratory droplets and by contact with surfaces contaminated by respiratory secretions.