Diseases and Treatment: I. Viral Diseases Part-I

Total Questions: 40

1. What is not true about virus? [Chhattisgarh P.C.S. (Pre) 2021]

(a) Virus term was coined by Dutch microbiologist M.W. Beijerinck.
(b) Nucleic acid genome of virus can be DNA or RNA-based.
(c) DNA-based viruses are usually single-stranded.
(d) RNA-based viruses accumulate more genetic changes (mutations) as compared to DNA-based viruses.

Correct Answer: (c) DNA-based viruses are usually single-stranded.

Solution:A DNA virus is a virus that has a genome made of deoxyribonucleic acid (DNA) that is replicated by a DNA polymerase. They can be divided between those that have two strands of DNA in their genome, called double-stranded DNA (dsDNA) viruses, and those that have one strand of DNA in their genome, called single-stranded DNA (ssDNA) viruses. Thus, DNA-based viruses are not usually single-stranded. Statements of other three options are correct.

2. A bacteriophage is a: [M.P.P.C.S. (Pre) 2017]

(a) bacterium with a tail
(b) newly formed bacterium
(c) bacterium infecting virus
(d) virus infecting bacterium

Correct Answer: (d) virus infecting bacterium

Solution:A virus infecting bacterium is called bacteriophage. It infects and replicated within bacteria and archaea. Like other viruses, its outer covering is made up of protein and nucleic acid (DNA or RNA) is present in it.

The word "bacteriophage" literally means "bacteria eater," because bacteriophages destroy their host cells. They are the most common biological entities in nature. Also known as phages, these viruses can be found everywhere bacteria exist, including, in the soil, deep within the earth's crust, inside plants and animals, and even in the oceans. Thousands of varieties of phages exist, each of which may infect only one type or a few types of bacteria or archaea. All bacteriophages are composed of a nucleic acid molecule that is surrounded by a protein structure. The nucleic acid may be either DNA or RNA, and it may be double-stranded or single-stranded.

3. Which of the following statements is/are correct? [I.A.S. (Pre) 2013]

Viruses lack enzymes necessary for the generation of energy.
Viruses can be cultured in any synthetic medium.
Viruses are transmitted from one organism to another by biological vectors only.

Select the correct answer using the codes given below:

(a) Only 1
(b) Only 2
(c) 1 and 3
(d) All of these

Correct Answer: (a) Only 1

Solution:A virus is a small infectious agent that replicates only inside the living cell of other organisms. Energy producing system is absent in them as viruses lack enzymes necessary for the generation of energy. Viruses exist in the form of independent particles. The viral particles also known as virions. Viruses are transmitted from one organism to another by various means e.g. by air, water, food, insects, contact etc.

4. Which of the following does not have any enzyme in its cells? [65th B.P.S.C. (Pre) 2019]

(a) Lichen
(b) Virus
(c) Bacteria
(d) Algae
(e) None of the above/More than one of the above

Correct Answer: (e) None of the above/More than one of the above

Solution:Lichen, bacteria and algae, all these have enzymes in its cells. The virus generally relies on the enzymes already present in the host cell or make enzymes that it needs using its own genome inside the host cell. Some viruses have no enzymes at all inside the viral particle itself. In other viruses, a small number of enzymes can be found inside the viral particle itself and also on the surface of some viruses. Enzymes found in some viral particles are reverse transcriptase, RNA-dependent RNA polymerase, an integrase, neuraminidase etc. Thus, the option (e) is the right answer.

5. The term ‘ACE2’ is talked about in the context of: [I.A.S. (Pre) 2021]

(a) genes introduced in the genetically modified plants
(b) development of India’s own satellite navigation system
(c) radio collars for wildlife tracking
(d) spread of viral diseases

Correct Answer: (d) spread of viral diseases

Solution:Angiotensin-converting enzyme 2 (ACE2) is a protein on the surface of many cell types. It is an enzyme that generates small proteins - by cutting up the larger protein angiotensinogen - that then go on to regulate functions in the cell. ACE2 is present in many cell types and tissues including the lungs, heart, blood, vessels, kidneys, liver and gastrointestinal tract. It is present in epithelial cells, which line certain tissues and create protective barriers. ACE2 is a vital element in a biochemical pathway that is critical to regulating processes such as blood pressure, wound healing and inflammation. ACE2 also serves as the entry point into cells for some coronaviruses, including HCoV-NL63, SARS-CoV, and SARS-CoV-2. The SARS-CoV-2 spike protein itself is known to damage the endothelium via downregulation of ACE2. Using the spike-like protein on its surface, the SARS-CoV-2 virus binds to ACE2 – like a key being inserted into a lock - prior to entry and infection of cells. Hence, ACE2 acts as a cellular doorway - a receptor - for the virus that causes COVID-19.

6. Which of the following disease is related to Coronavirus? [M.P. P.C.S. (Pre) 2020]

(a) MERS
(b) SARS
(c) COVID-19
(d) All of the above

Correct Answer: (d) All of the above

Solution:Coronaviruses are a group of refated RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the common cold (which is also caused by other viruses, predominantly rhinoviruses), while more lethal varieties can cause SARS (Severe Acute Respiratory Syndrome). MERS (Middle East Respiratory Syndrome) and COVID-19 (Coronavirus Disease 2019), which is causing an ongoing pandemic. In cows and pigs they cause diarrhea, while in mice they cause hepatitis and encephalomyelitis.

7. In the context of vaccines manufactured to prevent COVID-19 pandemic, consider the following statements: [I.A.S. (Pre) 2022]

1. The Serum Institute of India produced COVID-19 vaccine named Covishield using mRNA platform.
2. Sputnik V vaccine is manufactured using vector based platform.
3. Covaxin is an inactivated pathogen based vaccine.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (b) 2 and 3 only

Solution:For vaccination against COVID-19, India initially approved the Oxford-AstraZeneca vaccine (manufactured in India under license by Pune-based Serum Institute of India, under the trade name Covishield) and Covaxin (a vaccine developed by Bharat Biotech in association with the Indian Council of Medical Research and National Institute of Virology). They have since been joined by the Russian Sputnik V (manufactured under license by Dr. Reddy's Laboratories, with additional production from Serum Institute of India) and some other vaccines. Covishield and Sputnik V both are examples of non-replicating viral vector vaccines, using an adenovirus shell containing DNA that encodes a SARS-CoV-2 protein while Covaxin is a whole virion inactivated SARS-CoV-2 based vaccine. Pfizer-BioNTech and Moderna vaccines, have been developed by using mRNA platform. Hence statement 1 is incorrect while statements 2 and 3 are correct.

8. Covishield, the COVID vaccine of India which is approved by WHO, is manufactured by: [67th B.P.S.C. (Pre) 2022]

(a) Serum Institute
(b) Bharat Biotech
(c) Panacea Biotech
(d) Zydus Cadila
(e) None of the above/More than one of the

Correct Answer: (a) Serum Institute

9. What is the volume of each dose of Covishield Vaccine given to adults? [Chhattisgarh P.C.S. (Pre) 2021]

(a) 1 ml
(b) 2 ml
(c) 0.5 ml
(d) 1.5 ml

Correct Answer: (c) 0.5 ml

Solution:Covishield Vaccine has been developed by AstraZeneca with Oxford University in the UK and is being manufactured by the Serum Institute of India (SII) in Pune. Covishield Vaccine contains a non-replicating virus (a weakened chimpanzee adenovirus that causes common cold), that is genetically engineered to produce coronavirus proteins in the body, but the virus is weakened and cannot cause the disease. It provides active immunization against COVID-19 infection. Covishield regimen consists of two doses of 0.5 ml each. The Indian government has recommended that the time interval between 1st and 2nd doses should be between 12-16 weeks.

10. Which country exported Sputnik V COVID vaccine to India? [67th B.P.S.C. (Pre) 2022]

(a) America
(b) Russia
(c) UK
(d) France
(e) None of the above/More than one of the above

Correct Answer: (b) Russia

Solution:Sputnik V or Gam-COVID-Vac is an adenovirus viral vector vaccine for COVID-19 developed by the Gameleya Research Institute of Epidemiology and Microbiology in Russia. It is the world’s first registered combination vector vaccine for the prevention of COVID-19, having been registered on 11 August, 2020 by the Russian Ministry of Health. Russia exported Sputnik V COVID vaccine to India.

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