This set of Virology Multiple Choice Questions & Answers (MCQs) focuses on “Virus Like Particles(VLPs)”.
1. What are the most abundant microbes on earth?
a) Bacteria
b) Fungi
c) Algae
d) Virus-like particles (VLPs)
View Answer
Explanation: Vast majority of marine microbes are viruses. Microscopic observations of filtered sea water show the presence of virus particles outside the host cell. These viruses are not proved to infect host cells, so they are called Virus-like particles (VLPs). The average VLP density in seawater is between 106 to 107 per milliliter. Marine viruses are so abundant that VLPs are now recognized as the most abundant microbes on Earth.
2. Which of the following methods can be used to visualize virus particles directly?
a) Fluorescence microscopy
b) PCR
c) Western blotting
d) Southern blotting
View Answer
Explanation: Fluorescence microscopy is a common and easy method used to visualize viruses. Viruses are stained with a fluorescent dye, such as YO-PRO or SYBR Green and observed by fluorescence microscope. PCR is used for quantification of virus load. Western blotting detects specific proteins in a sample. Southern blotting is used to detect a specific DNA sequence in a sample.
3. Which of the following organisms are used as an expression system for producing Virus Like Particles(VLPs)?
a) Yeast
b) Mice
c) Algae
d) Zebrafish
View Answer
Explanation: Yeast is suitable for producing VLPs of structurally simple viruses. The advantages of using yeast are scalable fermentation, low risk of contamination by adventitious agents and low production cost. Many licensed VLPs are currently produced in different species of yeast. Yeast has the ability to produce VLPs of both enveloped and nonenveloped viruses.
4. Which of the following virus infections is prevented using Virus Like Particles (VLP) based vaccine?
a) Polio virus
b) Human papillomavirus
c) Influenza virus
d) Rubella virus
View Answer
Explanation: VLP based vaccine is used against human papillomavirus (HPV) which causes cervical cancer. HPV vaccine is a recombinant vaccine. The VLPs of HPV vaccine are produced by recombinant expression of the major capsid antigen L1 in yeast or insect cells. Gardasil is a VLP vaccine licensed for prevention of cervical cancer.
5. Which of the following is an application of Virus-like particles?
a) Antibody delivery
b) Antigen delivery
c) Plasma delivery
d) Blood delivery
View Answer
Explanation: Virus-like particles are composed of self-assembled viral structural proteins that mimic the live viruses but cannot cause infection. They are recognized by the host’s immune system and induce humoral and cellular immune response. So, Virus-like particles are used for antigen delivery which activates the immune system and causes antibody production.
6. Virus-like particles are infectious.
a) True
b) False
View Answer
Explanation: Virus-like particles are composed of multiple copies of viral recombinant structural protein. They show high immunogenic response as they resemble the live virus but due to the lack of viral genome, they cannot replicate inside the host cell. Therefore, Virus-like particles are non-infectious in nature.
7. Which of the following vaccines is effective against Hepatitis B?
a) Covaxin
b) DTaP
c) Rabipur
d) Recombivax
View Answer
Explanation: Recombivax is a VLP-based vaccine which is effective against Hepatitis B. Immunogenic Hepatitis B surface antigen is produced in genome free virus-like particles which allows large scale production of vaccines. The VLP vaccines are unable to infect host cells but can stimulate immune responses.
8. Which of the following is a well-known adjuvant used in VLP(Virus Like Particles) vaccine formulation?
a) Sodium salts
b) Copper salts
c) Magnesium salts
d) Aluminum salts
View Answer
Explanation: Adjuvant is a substance that is used to improve the effectiveness of a vaccine. Aluminum salts (Alum) are used as adjuvants in all approved VLPs vaccines. Insoluble aluminum salts such as aluminum phosphate, aluminum hydroxyl-phosphate, and aluminum hydroxide are used for the preparation of Alum-based vaccines.
9. Which of the following methods is used to determine the purity of Virus Like Particles (VLPs)?
a) TEM microscopy
b) Mass spectrometry
c) RP-HPLC
d) UV spectroscopy
View Answer
Explanation: Reverse phase-high performance liquid chromatography (RP-HPLC) is the most common method used to determine the purity, integrity and molecular weight of VLPs. RP-HPLC techniques have high sensibility and reproducibility which make them ideal for measuring purity and mass of VLP based vaccines.
10. Which proteins of human parvovirus can be used to produce VLP- based (Virus Like Particles) vaccine?
a) GP1 and GP2
b) VP1 and VP2
c) GN and GC
d) F and M
View Answer
Explanation: VP1 and VP2 are the two main structural proteins of human parvovirus. Human parvovirus B19 (HPVB19) VLPs composed of VP1 and VP2 proteins can be produced and self-assembled in Baculovirus/Insect cells (B/IC) expression system. These VLPs activate the immune system of host cells and provide protection against parvovirus infection in future.
11. Which of the following processes is used by the cells for uptake of Virus Like Particles (VLPs)?
a) Exocytosis
b) Osmosis
c) Endocytosis
d) Diffusion
View Answer
Explanation: Cells use receptor-mediated endocytosis for uptake of VLPs. During endocytosis, the plasma membrane surrounds the VLPs and buds off inside the cells as vesicles. The vesicles separate from the membrane and are transported across cytosol to combine with primary endosomes. Mature endosomes merge with pre-lysosomal vesicles to form lysosomes where foreign materials are broken down. However, VLPs have the ability to escape the endosomes before lysosomal degradation.
12. Which of the following is a chimeric Virus Like Particle vaccine?
a) MalariVax
b) Covaxin
c) Rabipur
d) Polio vaccine
View Answer
Explanation: MalariVax is a chimeric VLP- based vaccine which is effective against Malaria disease. It is comprised of two fused proteins, the core proteins of Hepatitis B virus and epitopes of proteins of malarial parasite. It is mass produced and assembled in bacterial expression system. The vaccine is currently undergoing clinical trial.
13. Which of the following proteins is used for production of Human papillomavirus-VLP (Virus Like Particles)?
a) L2
b) L1
c) L3
d) L4
View Answer
Explanation: The Human papillomavirus-VLP is composed of the L1 protein organized in 72 pentameric capsomers. The native Human papillomavirus contains the major and minor capsid proteins L1 and L2 respectively. However, during vaccine production by recombinant technology purified L1 protein self-assembles to form empty shells resembling Human papillomavirus that are able to elicit immune responses.
14. What is the size range of Virus-like particles?
a) 20-800 nm
b) 1-10 cm
c) 50-60 mm
d) 100-200 cm
View Answer
Explanation: Virus-like particles are self-assembled viral protein complexes with size ranging from 20-800nm. They can be either enveloped or non-enveloped. The capsid proteins of the VLPs can be arranged in one, two or three layers. The VLPs do not have a complete viral genome and are noninfectious.
15. When was the structure of Virus-like particles first identified?
a) 1921
b) 1858
c) 2000
d) 1968
View Answer
Explanation: The structure of Virus-like particles was first identified in the year 1968 in the serum of patients suffering from Down’s syndrome, leukemia and hepatitis. At that time the biological nature of these nanoparticles was unknown but it was shown that there were antigenic sites on the surface of these particles. Later, it was discovered that virus capsid, envelope and, sometimes, core viral proteins can form VLP structures.
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