Immunology Questions and Answers – Viral Infections

This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “Viral Infections”.

1. Which illness is caused due to viral infection in the upper respiratory tract?
a) Chickenpox
b) Herpes
c) Common Cold
d) Flu (influenza)
View Answer

Answer: c
Explanation: Common cold is an illness related to the upper respiratory tract. This is a type of viral infection as it is caused due to viruses. Cold is the most common type of viral infection and hence it is given the name “common cold”. It generally affects the nose or throat. The most common symptoms are fever, runny nose, throat pain, etc.  

2. Which of the following is NOT a way that virus can spread from person to person?
a) Breathing in air-borne droplets
b) Eating contaminated food or drinking contaminated water
c) Having a contact with the person who is already infected 
d) Touching inanimate things 
View Answer

Answer: d
Explanation: Most people believe that touching inanimate or non-living things can cause virus to be transmitted to our hands.  The reality of this fact is that virus always needs a living cell or host on which it can rely for living and completing its life cycle. On the other hand, breathing air-borne droplets while speaking to infected person, consumption of contaminated food and water or even having a direct contact with infected person can cause the virus to spread from person to person. 

3. Which of the following infection/disease caused by virus can be healed by immunity itself without severe medications?
a) Common cold
b) Dehydration 
c) Pneumonia
d) Human immunodeficiency virus
View Answer

Answer: a
Explanation: Viral infections such as common cold and normal flu does not need severe medications as they are self-limiting (mostly in healthy people having a strong immunity). If a person has a strong immunity, it can fight against common cold and flu. It will surely cause illness for a specific period of time but once the immunity is in action, symptoms start disappearing as immune system attacks the virus. On the other hand, some viral diseases can lead to life threatening complications like dehydration, pneumonia, human immunodeficiency virus, etc. People at risk are usually those who have secondary illness or diseases due to which their immunity is low and weak. These people need serious medications in order to attack and kill the virus. 

4. Which of the following disease is NOT caused by Human papillomavirus (HPV)?
a) Cervical dysplasia
b) Genital warts
d) Cervical cancer
View Answer

Answer: c
Explanation: Human papillomavirus (HPV) is one of the types of virus that caused various viral diseases like HPV infections, cervical dysplasia, genital warts and cervical cancers. HPV usually affects the genital area, throat or mouth. It can be passed from one person to another by direct contact. HPV can also lead to anal cancer which can be a serious condition. On the other hand, AIDS is caused by Human Immunodeficiency Virus (HIV). It directly attacks the immune system and hence termed as chronic disease. AIDS is life-threatening as HIV weakens the immune system completely. 

5. Shingles and Chickenpox is caused by which virus?
a) Rotavirus
b) Respiratory syncytial virus (RSV)
c) West Nile virus
d) Varicella zoster virus
View Answer

Answer: d
Explanation: Varicella zoster virus (VZV) is a human virus and it belongs to herpesvirus family. It mainly causes Chickenpox and Shingles by exposure either through direct contact or through airborne spread from respiratory droplets. VZV primarily causes fever and common symptoms but as and when the virus spreads throughout the body, it leads to more severe diseases and complications. 

6. Which one of the following is the most important risk factor for being infected by virus?
a) Not getting enough rest
b) High levels of stress
c) Sharing needles to inject drugs
d) Lack of healthy diet
View Answer

Answer: c
Explanation: Although all of the above is considered to be risk factors for contacting viral infections and disease, getting injected by used needles still remains one of the most important and primary risk factors. The used needles are non-sterile and may contain harmful viruses on it for some time. It may also contain a few blood drops of the previous patient which might be transmitted to the new patient if the same needle is reused. It may lead the patient in danger and also cause death of weak patients.

7. Which of the following is NOT a viral infection?
a) COVID-19
b) Ebola
d) Gonorrhea
View Answer

Answer: d
Explanation: Gonorrhea is a sexually transmitted disease (STD) and it is caused by some type of bacteria called Neisseria gonorrhoeae. It causes pain in the testicles, burning sensations near the genital area or even itching. This can lead to infertility and further lead to enhance activity of HIV. The bacterial transmission can occur due to unhealthy and unsafe intercourse. On the other hand, infections caused due to virus are HIV/AIDS, ebola and COVID-19. These infections have the ability to be transmitted by air or skin-to-skin contact with another person. 

8. Who developed Rabies Vaccine?
a) Pasteur and Roux
b) Edward Jenner and Pasteur
c) Hideyo Noguchi 
d) Max Theiler and Roux
View Answer

Answer: a
Explanation: Rabies is an extremely dangerous and life-threatening infection caused by rabid dogs by attacking humans. Rabies causes foaming at the mouth by stimulating the salivary glands to produce abundant quantity of saliva which causes transmission of the virus. Pasteur and Roux developed a rabies vaccine in 1885. The virus was forces to limit the effect of rabies by passing the virulent strain isolated from rabid dogs. This vaccine is given to patients (who have been in contact with rabid dogs) in the form of 10-14 injections over a period of 2 weeks.

9. Bats transmit COVID-19 to humans.
a) True
b) False
View Answer

Answer: b
Explanation: The virus that causes COVID-19 has not been isolated from any resident breeding bat species. There are no zoonotic coronaviruses found in bats. It is important to understand that COVID-19 is transmitted from one human to another.  A coronavirus with 96% of its genome in common with SARS-CoV-2 has been found in a single species of bat in China. However, we, as humans, share 96% of our genome with chimpanzees. As a result, there is no relation of transmission of COVID-19 from bats. 

10. Which one of the following is one of the oldest antiviral drugs?
a) Acyclovir
b) Lamivudine
c) Foscarnet
d) Penciclovir 
View Answer

Answer: a
Explanation: Antiviral drugs are nucleoside analogues. They behave like fake DNA-building blocks which misleads the virus. The virus incorporates into their genomes during replication. Due to this, the life cycle of virus is halted because its DNA gets activated. Acyclovir is known to be the oldest antiviral drug which is used in treatments of various infections. 

11. Canine parvovirus mainly affects which species?
a) Human
b) Dogs
c) Cats 
d) Horses 
View Answer

Answer: b
Explanation: Canine parvovirus (CPV) is a contagious virus and mainly affects dogs. It can spread from dog-to-dog just how COVID-19 spreads from human-to-human. However, it may also infect foxes, cats and wolves but at a lower rate. Dogs that show signs of illness within three to seven days are predicted to be infected by CPV. They may feel lethargic and have vomiting sensations. ELISA test or hemagglutination test is done in order to detect CPV.

12. What is the term used for genetically modifying viruses to treat disease?
a) Nanotechnology
b) Virotherapy
c) Viral therapy
d) Viral DNA replication
View Answer

Answer: b
Explanation: Virotherapy is a branch of medicine which explores the use of viruses to kill cancers and treat various diseases. It involves genetic modifications of virus in order to limit the mechanism of its life cycle. This modification reproduces cancer cells and destroy them and they do not affect healthy cells.

13. Which is the smallest DNA contaminating virus?
a) Mimivirus
b) AAV
c) Banna virus
d) Ebolavirus
View Answer

Answer: b
Explanation: Adeno-associated virus (AAV) is the smallest DNA contaminating virus which infects humans. Its average size is around 20nm. It does not have any severe effects on human but it weakens the immune system to a great extent. AAV belongs to family Parvoviridae. This virus is of great importance in the study of gene therapy.  

14. Where does the genome replication of DNA viruses take place?
a) Nucleus of the cell
b) Cytoplasm
c) Cell membrane
d) Within the cell
View Answer

Answer: a
Explanation: The genome replication of DNA viruses takes place the nucleus of the cell. Viral genomes are replicated, assembled and expressed in the intracellular structures. The genome replication of DNA viruses requires relocalization of organelles and reorganization of the endoplasmic reticulum, golgi apparatus as well as mitochondria. Genome replication includes redistribution of chromatin and components of nuclear domains. 

15. Which one of the following is a dsDNA virus?
a) Retroviridae
b) Metaviridae
c) Hepadnaviridae
d) Pseudoviridae
View Answer

Answer: c
Explanation: Hepadnaviridae is a virus which is about 40-48nm in diameter. It is composed of double stranded DNA molecule and hence termed as a dsDNA virus. It also comprises of single stranded DNA region associated with DNA polymerase. On the other hand, Retroviridae, Metaviridae and Pseudoviridae are some examples of ssRNA virus as they are composed of single stranded RNA regions. This ssRNA is further copied into dsDNA by mechanism of revers transcription. This is also mediated by reverse transcriptase. 

Sanfoundry Global Education & Learning Series – Immunology.

To practice all areas of Immunology, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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