MCQ Quiz: Virology

Welcome, PharmD students, to this MCQ quiz exploring the fascinating world of Virology! Viruses are unique obligate intracellular parasites responsible for a wide range of human diseases, from the common cold to global pandemics. Understanding their basic structure, replication strategies, mechanisms of pathogenesis, and how our immune system responds to them is fundamental for comprehending viral illnesses and the principles behind antiviral therapies and vaccines. This quiz will test your knowledge on these core virological concepts, including important viral families like influenza, herpesviruses, hepatitis viruses, retroviruses, and coronaviruses. Let’s begin!

1. Viruses are best described as:

• a) Free-living microorganisms capable of independent replication.
• b) Obligate intracellular parasites that require host cell machinery to replicate.
• c) Prokaryotic cells with a simple structure.
• d) Multicellular organisms that cause infections.

Answer: b) Obligate intracellular parasites that require host cell machinery to replicate.

2. The basic structural components of all viruses include:

• a) A cell wall and a nucleus.
• b) A nucleic acid genome (DNA or RNA) and a protein coat (capsid).
• c) Mitochondria and endoplasmic reticulum.
• d) Ribosomes and a plasma membrane.

Answer: b) A nucleic acid genome (DNA or RNA) and a protein coat (capsid).

3. An “enveloped virus” acquires its envelope from:

• a) Self-assembly of viral proteins only.
• b) The host cell membrane (e.g., plasma membrane, nuclear membrane) during budding.
• c) The extracellular environment.
• d) Bacterial cell walls.

Answer: b) The host cell membrane (e.g., plasma membrane, nuclear membrane) during budding.

4. The correct sequence of steps in a typical viral replication cycle is:

• a) Uncoating, Attachment, Biosynthesis, Release, Assembly, Penetration
• b) Attachment, Penetration, Uncoating, Biosynthesis, Assembly, Release
• c) Biosynthesis, Assembly, Release, Attachment, Penetration, Uncoating
• d) Release, Assembly, Biosynthesis, Uncoating, Penetration, Attachment

Answer: b) Attachment, Penetration, Uncoating, Biosynthesis, Assembly, Release

5. Retroviruses, such as HIV, are unique because they contain the enzyme _______, which synthesizes DNA from an RNA template.

• a) DNA polymerase
• b) RNA polymerase
• c) Reverse transcriptase
• d) Helicase

Answer: c) Reverse transcriptase

6. Influenza viruses belong to the Orthomyxoviridae family and possess a segmented _______ genome.

• a) Single-stranded DNA
• b) Double-stranded DNA
• c) Single-stranded RNA
• d) Double-stranded RNA

Answer: c) Single-stranded RNA

7. “Antigenic drift” in influenza viruses refers to minor changes in viral antigens due to point mutations, leading to seasonal epidemics. “Antigenic shift” refers to:

• a) The same process but occurring more slowly.
• b) Major changes in viral antigens due to reassortment of gene segments from different viral strains, potentially leading to pandemics.
• c) The virus shifting its host range.
• d) The virus becoming non-infectious.

Answer: b) Major changes in viral antigens due to reassortment of gene segments from different viral strains, potentially leading to pandemics.

8. Herpesviruses are a family of _______ viruses known for their ability to establish latency and cause recurrent infections.

• a) RNA, non-enveloped
• b) RNA, enveloped
• c) DNA, enveloped
• d) DNA, non-enveloped

Answer: c) DNA, enveloped

9. Varicella-Zoster Virus (VZV) causes which two distinct clinical syndromes?

• a) Common cold and influenza.
• b) Chickenpox (varicella) as the primary infection and shingles (herpes zoster) upon reactivation.
• c) Infectious mononucleosis and roseola.
• d) Hepatitis A and hepatitis B.

Answer: b) Chickenpox (varicella) as the primary infection and shingles (herpes zoster) upon reactivation.

10. Human Immunodeficiency Virus (HIV) primarily targets and destroys which type of immune cells, leading to Acquired Immunodeficiency Syndrome (AIDS)?

• a) B lymphocytes
• b) Neutrophils
• c) CD4+ T lymphocytes (helper T cells)
• d) Natural Killer (NK) cells

Answer: c) CD4+ T lymphocytes (helper T cells)

11. Hepatitis B virus (HBV) is a DNA virus that can cause chronic infection, leading to an increased risk of:

• a) Only acute, self-limiting hepatitis.
• b) Cirrhosis and hepatocellular carcinoma.
• c) Gallstones.
• d) Peptic ulcer disease.

Answer: b) Cirrhosis and hepatocellular carcinoma.

12. Hepatitis C virus (HCV) is an RNA virus primarily transmitted via:

• a) Fecal-oral route.
• b) Respiratory droplets.
• c) Contaminated blood and blood products (e.g., IV drug use, unscreened transfusions).
• d) Mosquito bites.

Answer: c) Contaminated blood and blood products (e.g., IV drug use, unscreened transfusions).

13. Epstein-Barr Virus (EBV), a herpesvirus, is the primary cause of:

• a) Genital herpes
• b) Shingles
• c) Infectious mononucleosis (“mono”)
• d) Cytomegalovirus infection

Answer: c) Infectious mononucleosis (“mono”)

14. Coronaviruses are RNA viruses that can cause:

• a) Only mild common colds.
• b) A spectrum of respiratory illnesses, ranging from the common cold to severe acute respiratory syndromes like SARS, MERS, and COVID-19.
• c) Only gastrointestinal infections.
• d) Primarily skin infections.

Answer: b) A spectrum of respiratory illnesses, ranging from the common cold to severe acute respiratory syndromes like SARS, MERS, and COVID-19.

15. Interferons are host cytokines that play a crucial role in the innate immune response against viral infections by:

• a) Directly neutralizing extracellular virus particles.
• b) Inducing an antiviral state in uninfected cells and inhibiting viral replication.
• c) Stimulating bacterial phagocytosis.
• d) Causing viral lysis.

Answer: b) Inducing an antiviral state in uninfected cells and inhibiting viral replication.

16. Viral latency is a period during which:

• a) The virus replicates at a very high rate, causing acute symptoms.
• b) The virus is completely cleared from the body by the immune system.
• c) The virus remains dormant within host cells, with limited gene expression and no active replication, but can reactivate later.
• d) The virus only infects non-human primates.

Answer: c) The virus remains dormant within host cells, with limited gene expression and no active replication, but can reactivate later.

17. The capsid of a virus is a protein shell that primarily functions to:

• a) Synthesize viral proteins.
• b) Replicate the viral genome.
• c) Enclose and protect the viral nucleic acid.
• d) Facilitate viral budding from the host cell.

Answer: c) Enclose and protect the viral nucleic acid.

18. The “uncoating” step in the viral replication cycle involves:

• a) The virus attaching to the host cell surface.
• b) The release of the viral genome from its capsid into the host cell cytoplasm or nucleus.
• c) The assembly of new viral particles.
• d) The budding of enveloped viruses from the host cell.

Answer: b) The release of the viral genome from its capsid into the host cell cytoplasm or nucleus.

19. Which of the following diagnostic methods is commonly used for direct detection of viral nucleic acids (DNA or RNA) in a patient sample?

• a) Gram stain
• b) Bacterial culture
• c) Polymerase Chain Reaction (PCR) or other Nucleic Acid Amplification Tests (NAATs)
• d) Skin prick test

Answer: c) Polymerase Chain Reaction (PCR) or other Nucleic Acid Amplification Tests (NAATs)

20. Serological tests for viral infections typically detect the presence of:

• a) Viral antigens in the blood.
• b) Host antibodies (e.g., IgM, IgG) produced in response to the viral infection.
• c) Viral enzymes.
• d) Intact virus particles.

Answer: b) Host antibodies (e.g., IgM, IgG) produced in response to the viral infection.

21. The presence of IgM antibodies against a specific virus generally indicates:

• a) Past infection or immunity from vaccination.
• b) A recent or acute primary infection.
• c) That the virus is latent.
• d) Complete eradication of the virus.

Answer: b) A recent or acute primary infection.

22. Viruses are classified based on several characteristics. Which of these is a primary classification criterion?

• a) The color of the virus under a microscope.
• b) The type of nucleic acid (DNA or RNA) and its structure (single- or double-stranded).
• c) The geographical region where the virus was first discovered.
• d) The price of the antiviral drug used to treat it.

Answer: b) The type of nucleic acid (DNA or RNA) and its structure (single- or double-stranded).

23. Hepatitis A virus (HAV) is primarily transmitted via the:

• a) Respiratory route
• b) Bloodborne route
• c) Fecal-oral route (e.g., contaminated food or water)
• d) Sexual route

Answer: c) Fecal-oral route (e.g., contaminated food or water)

24. Which of the following herpesviruses is a common cause of opportunistic infections (e.g., retinitis, colitis, pneumonia) in severely immunocompromised individuals, such as those with advanced AIDS?

• a) Varicella-Zoster Virus (VZV)
• b) Epstein-Barr Virus (EBV)
• c) Cytomegalovirus (CMV)
• d) Herpes Simplex Virus Type 1 (HSV-1)

Answer: c) Cytomegalovirus (CMV)

25. Viral pathogenesis refers to the mechanisms by which viruses:

• a) Replicate their genome.
• b) Cause disease in the host.
• c) Attach to host cells.
• d) Are classified.

Answer: b) Cause disease in the host.

26. One way viruses can damage host cells is by directly causing cell lysis (bursting) during:

• a) The uncoating phase.
• b) The release of newly formed viral particles (for some non-enveloped viruses).
• c) Viral latency.
• d) Viral attachment.

Answer: b) The release of newly formed viral particles (for some non-enveloped viruses).

27. The interaction of viruses with the host immune system can sometimes lead to immunopathology, meaning:

• a) The virus directly boosts the immune system.
• b) The host’s immune response to the virus contributes significantly to the tissue damage and symptoms of the disease.
• c) The virus becomes completely resistant to the immune system.
• d) The immune system ignores the virus.

Answer: b) The host’s immune response to the virus contributes significantly to the tissue damage and symptoms of thedisease.

28. The “spike protein” of SARS-CoV-2 is crucial for which step in its replication cycle?

• a) Viral genome replication
• b) Viral assembly
• c) Attachment to host cell receptors (e.g., ACE2) and entry into the host cell.
• d) Release of new virions.

Answer: c) Attachment to host cell receptors (e.g., ACE2) and entry into the host cell.

29. The neuraminidase enzyme of the influenza virus is important for:

• a) Viral entry into the host cell.
• b) Replication of the viral RNA.
• c) The release of newly formed virions from the infected host cell.
• d) Protecting the viral genome.

Answer: c) The release of newly formed virions from the infected host cell. (This is a target for antiviral drugs like oseltamivir).

30. Which statement accurately describes a difference between DNA viruses and RNA viruses regarding their replication?

• a) DNA viruses always replicate in the cytoplasm, while RNA viruses always replicate in the nucleus.
• b) Most DNA viruses replicate in the host cell nucleus (using host or viral DNA polymerase), while most RNA viruses replicate in the cytoplasm (often using a viral RNA-dependent RNA polymerase).
• c) RNA viruses do not require uncoating.
• d) DNA viruses always have a much higher mutation rate than RNA viruses.

Answer: b) Most DNA viruses replicate in the host cell nucleus (using host or viral DNA polymerase), while most RNA viruses replicate in the cytoplasm (often using a viral RNA-dependent RNA polymerase).

31. A “prion” is different from a virus in that it is:

• a) A type of bacteria.
• b) An infectious protein particle that lacks nucleic acid.
• c) A complex multicellular parasite.
• d) A type of fungus.

Answer: b) An infectious protein particle that lacks nucleic acid.

32. Viral tropism refers to the:

• a) Speed of viral replication.
• b) Specificity of a virus for particular host tissues or cell types.
• c) Way a virus is transmitted.
• d) Size of the viral capsid.

Answer: b) Specificity of a virus for particular host tissues or cell types.

33. The common cold can be caused by various viruses, most frequently by:

• a) Influenza viruses
• b) Rhinoviruses and Coronaviruses (non-SARS/MERS types)
• c) Herpes simplex viruses
• d) Hepatitis A virus

Answer: b) Rhinoviruses and Coronaviruses (non-SARS/MERS types)

34. Which of the following is a characteristic of an acute viral infection (e.g., influenza)?

• a) Prolonged, lifelong presence of the virus with continuous low-level replication.
• b) Rapid onset of disease, relatively brief period of symptoms, and virus elimination by the host immune response.
• c) The virus remains dormant for many years before causing symptoms.
• d) The virus integrates into the host genome and is passed to daughter cells.

Answer: b) Rapid onset of disease, relatively brief period of symptoms, and virus elimination by the host immune response.

35. Cytopathic effects (CPE) are changes in host cells caused by viral infection that can be observed in cell culture. Examples include:

• a) Increased host cell proliferation.
• b) Cell rounding, lysis, syncytia formation (fusion of cells), or inclusion bodies.
• c) Enhanced production of host proteins.
• d) Conversion of host cells to bacterial cells.

Answer: b) Cell rounding, lysis, syncytia formation (fusion of cells), or inclusion bodies.

36. Some viruses are “oncogenic,” meaning they can:

• a) Only cause acute, self-limiting infections.
• b) Contribute to the development of cancer.
• c) Only infect plants.
• d) Be easily treated with antibiotics.

Answer: b) Contribute to the development of cancer. (e.g., HPV, HBV, HCV, EBV).

37. The process of “budding” is a common mechanism for the release of _______ viruses from host cells.

• a) non-enveloped
• b) enveloped
• c) bacterial
• d) fungal

Answer: b) enveloped

38. A key component of the adaptive immune response to viral infections that is crucial for clearing infected cells is:

• a) Neutrophil phagocytosis.
• b) Complement activation.
• c) Cytotoxic T lymphocytes (CTLs or CD8+ T cells).
• d) Mast cell degranulation.

Answer: c) Cytotoxic T lymphocytes (CTLs or CD8+ T cells).

39. The target for many antiviral drugs is often:

• a) The bacterial cell wall.
• b) Viral-specific enzymes (e.g., reverse transcriptase, protease, polymerase) or processes essential for viral replication.
• c) Host ribosomes.
• d) Fungal ergosterol.

Answer: b) Viral-specific enzymes (e.g., reverse transcriptase, protease, polymerase) or processes essential for viral replication.

40. Which of these hepatitis viruses does NOT typically cause chronic infection?

• a) Hepatitis B Virus (HBV)
• b) Hepatitis C Virus (HCV)
• c) Hepatitis A Virus (HAV)
• d) Hepatitis D Virus (HDV – requires HBV coinfection)

Answer: c) Hepatitis A Virus (HAV)

41. Herpes Simplex Virus Type 1 (HSV-1) typically establishes latency in the:

• a) Dorsal root ganglia.
• b) Trigeminal ganglia.
• c) Sacral ganglia.
• d) Motor neurons.

Answer: b) Trigeminal ganglia.

42. The ability of influenza virus to undergo antigenic shift is due to its:

• a) Double-stranded DNA genome.
• b) Segmented RNA genome, which allows for reassortment in co-infected cells.
• c) Lack of a viral envelope.
• d) Extremely low mutation rate.

Answer: b) Segmented RNA genome, which allows for reassortment in co-infected cells.

43. Which of the following is an example of passive immunization against a viral disease?

• a) Administering the MMR vaccine.
• b) Administering Hepatitis B immune globulin (HBIG) after exposure to HBV.
• c) Annual influenza vaccination.
• d) Natural infection with chickenpox.

Answer: b) Administering Hepatitis B immune globulin (HBIG) after exposure to HBV.

44. Viral load assays (e.g., for HIV or HCV) measure the:

• a) Number of host antibodies.
• b) Number of infected host cells.
• c) Amount of viral nucleic acid (RNA or DNA) in a given volume of patient sample (e.g., plasma).
• d) Strength of the viral capsid.

Answer: c) Amount of viral nucleic acid (RNA or DNA) in a given volume of patient sample (e.g., plasma).

45. A common strategy for viral vaccines is to use:

• a) Live, fully virulent viruses.
• b) Attenuated (weakened) live viruses, inactivated (killed) viruses, or subunits/proteins of the virus.
• c) Only bacterial toxins.
• d) Broad-spectrum antibiotics.

Answer: b) Attenuated (weakened) live viruses, inactivated (killed) viruses, or subunits/proteins of the virus.

46. The family Retroviridae, which includes HIV, is characterized by its ability to:

• a) Replicate entirely in the cytoplasm without a DNA intermediate.
• b) Convert its RNA genome into a DNA copy that integrates into the host chromosome.
• c) Only infect plant cells.
• d) Form endospores.

Answer: b) Convert its RNA genome into a DNA copy that integrates into the host chromosome.

47. The interaction of viruses with the immune system can sometimes lead to “immune evasion” strategies by the virus, such as:

• a) Antigenic variation (changing surface proteins).
• b) Inhibition of MHC presentation.
• c) Latency.
• d) All of the above.

Answer: d) All of the above.

48. Which statement best describes “viroids”?

• a) They are viruses that infect bacteria.
• b) They are small, circular, single-stranded RNA molecules that infect plants and lack a protein coat.
• c) They are complex enveloped DNA viruses.
• d) They are infectious proteins.

Answer: b) They are small, circular, single-stranded RNA molecules that infect plants and lack a protein coat.

49. The primary challenge in developing broadly effective antiviral drugs is that:

• a) Viruses have very complex metabolic pathways that are easy to target.
• b) Viruses utilize host cell machinery for replication, so drugs targeting viral processes may also be toxic to host cells.
• c) Viruses are not affected by any chemical compounds.
• d) All viral infections are self-limiting and mild.

Answer: b) Viruses utilize host cell machinery for replication, so drugs targeting viral processes may also be toxic to host cells.

50. Understanding basic virology is essential for pharmacists to:

• a) Perform viral cultures in the pharmacy.
• b) Counsel patients on viral diseases, vaccinations, appropriate use of antiviral medications, and infection control measures.
• c) Prescribe antiviral medications for all conditions.
• d) Develop new viral vectors for gene therapy.

Answer: b) Counsel patients on viral diseases, vaccinations, appropriate use of antiviral medications, and infection control measures.