Podcast
Questions and Answers
Which of the following viruses can be transmitted through respiratory droplets?
Which of the following viruses can be transmitted through respiratory droplets?
Vector-borne transmission requires a living vector to spread viruses.
Vector-borne transmission requires a living vector to spread viruses.
True
What type of transmission occurs when an infected individual contaminates food or water?
What type of transmission occurs when an infected individual contaminates food or water?
Fecal-Oral Transmission
Viruses can be transmitted from an infected mother to her child through ______.
Viruses can be transmitted from an infected mother to her child through ______.
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Which of the following statements about Gram staining is true for some viruses?
Which of the following statements about Gram staining is true for some viruses?
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Match the type of transmission with its correct example:
Match the type of transmission with its correct example:
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Name one virus that can survive both within and outside the host.
Name one virus that can survive both within and outside the host.
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All viruses can be cultivated in synthetic media.
All viruses can be cultivated in synthetic media.
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Which of the following viruses are notably transmitted through bloodborne transmission?
Which of the following viruses are notably transmitted through bloodborne transmission?
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Zoonotic transmission involves the spread of viruses from humans to animals.
Zoonotic transmission involves the spread of viruses from humans to animals.
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What is the primary mode of transmission for HIV?
What is the primary mode of transmission for HIV?
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The outer protective layer of a virus that may be derived from the host cell membrane is called the ______.
The outer protective layer of a virus that may be derived from the host cell membrane is called the ______.
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Match the following viruses with their primary transmission mode:
Match the following viruses with their primary transmission mode:
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What helps prevent indirect transmission of viruses through contaminated surfaces?
What helps prevent indirect transmission of viruses through contaminated surfaces?
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A capsid is a proteinous shell that in encases the viral nucleic acid.
A capsid is a proteinous shell that in encases the viral nucleic acid.
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Many viruses, such as SARS-CoV-2, are believed to have originated in ______.
Many viruses, such as SARS-CoV-2, are believed to have originated in ______.
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What is the role of structural proteins in viruses?
What is the role of structural proteins in viruses?
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Viroids are intracellular RNA particles that can possess a protein coat.
Viroids are intracellular RNA particles that can possess a protein coat.
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Name one disease caused by prions.
Name one disease caused by prions.
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The particles responsible for diseases in plants that require a helper virus for replication are called __________.
The particles responsible for diseases in plants that require a helper virus for replication are called __________.
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Match the following terms with their correct definitions:
Match the following terms with their correct definitions:
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Which example is associated with prions?
Which example is associated with prions?
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Non-structural proteins play a critical role in providing the shape of the virus.
Non-structural proteins play a critical role in providing the shape of the virus.
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What is the primary function of the International Committee on Viral Taxonomy?
What is the primary function of the International Committee on Viral Taxonomy?
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Which suffix is used for viral families?
Which suffix is used for viral families?
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The smallest RNA virus belongs to the Picornaviridae family.
The smallest RNA virus belongs to the Picornaviridae family.
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What is the classification of a virus that has a reverse transcriptase enzyme?
What is the classification of a virus that has a reverse transcriptase enzyme?
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The largest virus is the ______.
The largest virus is the ______.
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Match the following viral families with their classification (DNA or RNA):
Match the following viral families with their classification (DNA or RNA):
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Which of the following is NOT a mode of transmission for viruses?
Which of the following is NOT a mode of transmission for viruses?
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Naked viruses are susceptible to ether.
Naked viruses are susceptible to ether.
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What type of nucleic acid does the Mononegavirales order consist of?
What type of nucleic acid does the Mononegavirales order consist of?
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Which of the following viruses belongs to the Filoviridae family?
Which of the following viruses belongs to the Filoviridae family?
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All viruses can reproduce independently outside a host cell.
All viruses can reproduce independently outside a host cell.
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Name the stage of viral replication where the viral nucleic acid is released into the host cell.
Name the stage of viral replication where the viral nucleic acid is released into the host cell.
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The process by which viruses enter host cells can occur through ________, viropexis, or endocytosis.
The process by which viruses enter host cells can occur through ________, viropexis, or endocytosis.
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Match the following viral entry methods with their descriptions:
Match the following viral entry methods with their descriptions:
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What is the optimum temperature for viral adhesion to the host cell receptor?
What is the optimum temperature for viral adhesion to the host cell receptor?
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The loss of infectivity can occur when viral enzymes are denatured.
The loss of infectivity can occur when viral enzymes are denatured.
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List one example of a glycoprotein associated with HIV.
List one example of a glycoprotein associated with HIV.
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What is the term used for the period of dormancy when no symptoms are expressed after the disappearance of infectious viral particles?
What is the term used for the period of dormancy when no symptoms are expressed after the disappearance of infectious viral particles?
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RNA replication of all viruses occurs in the nucleus.
RNA replication of all viruses occurs in the nucleus.
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What enzyme converts single-stranded RNA of HIV to single-stranded DNA?
What enzyme converts single-stranded RNA of HIV to single-stranded DNA?
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The process of _______ turns mRNA codon sequences into proteins.
The process of _______ turns mRNA codon sequences into proteins.
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Match the following viral terms with their definitions:
Match the following viral terms with their definitions:
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Which virus has the shortest incubation period of 12 hours?
Which virus has the shortest incubation period of 12 hours?
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Synthesis of viral proteins involves both transcription and translation processes.
Synthesis of viral proteins involves both transcription and translation processes.
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What are the two types of viral proteins mentioned?
What are the two types of viral proteins mentioned?
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Study Notes
Medical Virology (MLSC 441)
- Course offered by the Department of Medical Laboratory Science, School of Public & Allied Health, Babcock University, Ilishan-Remo.
- Academic session 2024/2025.1
- Head of Unit: Mr. S.S. Enitan (Medical Microbiology & Parasitology Option)
- Contact information included (email, GSM, WhatsApp)
What is Virology?
- Virology is a branch of medical science studying medically important viruses.
- It involves the study of viral biology, pathogenicity, pathogenesis, epidemiology, surveillance, monitoring, diagnosis, and prevention of viral diseases in humans.
What is a Virus?
- A virus is a submicroscopic, obligate, parasitic entity replicating within a susceptible host cell.
- Submicroscopic: Observable only with an electron microscope.
- Obligate: Can only survive within a host.
- Parasite: Survival dependent on the host.
- Entity: Refers to a living entity.
- Replicating: Can reproduce and produce offspring.
- Susceptible host: Hosts vulnerable to viral attack, lacking resistance.
Viruses: Living or Non-Living?
- Viruses exhibit both living and non-living characteristics:
- Living within a host: Can metabolize and reproduce/multiply.
- Non-living outside a host: Inactive (inert), do not metabolize outside a host, exist as crystals.
Attributes of a Virus
- Small relative to other microorganisms, their genome is either DNA or RNA, not both.
- Obligate intracellular agents surviving within living hosts.
- Intracellular nature limits drug availability compared to bacterial infections.
- Acellular (non-celled), non-motile, lack tRNA.
- Visualized with electron microscopes and can be demonstrable with cell staining but not Gram staining.
- Insusceptible to antibiotics but susceptible to antiviral agents.
- Are metabolically inert and crystallizable outside of the host.
- Cultivated in tissue cultures but not in synthetic media.
- Sensitive to alkaline pH and hypochlorite.
Differences Between Bacteria and Viruses
- Bacteria are cellular; viruses are acellular.
- Bacteria may be motile; viruses are non-motile.
- Bacteria have tRNA; viruses lack tRNA.
- Bacteria have both DNA and RNA genomes; viruses have either DNA or RNA.
- Bacteria can be visualized with compound microscopes; viruses require electron microscopes.
- Bacteria are Gram-stainable; some viruses are demonstrable with cell stains but not Gram stain.
- Bacteria are susceptible to antibiotics; viruses are not.
- Most bacteria survive within and outside the host; most viruses are metabolically inert outside the host.
- Bacteria can be cultivated in synthetic media; viruses cannot, require tissue culture.
Transmission of Viruses
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Direct Contact: Transmission through physical contact (touching, kissing, sexual contact).
- Examples: Herpes simplex, HPV.
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Respiratory Droplets: Transmission through droplets expelled during breathing, talking, coughing, or sneezing.
- Examples: Influenza, COVID-19, common cold.
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Airborne Transmission: Transmission through suspended viruses in the air for extended periods.
- Examples: Measles.
-
Fecal-Oral Transmission: Transmission via contaminated food, water, or surfaces.
- Examples: Hepatitis A, norovirus.
-
Vector-Borne Transmission: Transmission via arthropods (insects, etc.).
- Examples: Zika virus (Aedes mosquitoes), Lyme disease (ticks).
-
Vertical Transmission: Transmission from mother to child during pregnancy, childbirth, or breastfeeding.
- Examples: HIV, CMV, hepatitis B.
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Indirect Contact: Transmission through surfaces or objects contaminated with viruses.
- Example: Ebola, SARS-CoV-2 (from bats or other wild animals)
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Bloodborne Transmission: Transmission via infected blood or blood products.
- Example: HIV, Hepatitis C.
-
Sexual Transmission: Transmission via sexual contact (vaginal, anal, oral).
- Example: HIV, herpes, HPV
Viral Structure
- Viral nucleic acid core: The region within the virus containing its nucleic acid.
-
Capsid: The protein shell encapsulating the viral nucleic acid.
- Composed of polypeptide units called capsomeres.
- Protects the viral nucleic acid and imparts symmetry/shape to the virus.
- Serves as viral epitopes in the capsid.
- Coded in the viral genome, characterized serologically.
- Nucleocapsid: Viral nucleic acid + its capsid; sometimes used synonymously with "naked" virus.
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Envelope: Lipoprotein shell that encloses the nucleocapsid.
- Constructed from peptide monomers (peplomeres).
- Acquired from the host cell membrane.
- Specific glycoprotein spikes coded by the virus are present.
- Characterized serologically.
Viral Replication (General) - Stages
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Attachment/Adsorption: Virus binds to host cell receptors.
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Penetration: Entry of the virus into the host cell. (Pinocytosis, Viropexis, Endocytosis, Fusion, Direct Penetration).
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Uncoating: Release of the viral nucleic acid into the host cell.
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Replication of viral nucleic acid: DNA or RNA replication.
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Synthesis of viral proteins: Production of viral proteins.
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Assembly: Combining viral components.
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Release: Viral offspring release from the host cell. (Lysis, Budding)
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Latency: A period where virus is present in the host cell without replication or expression of symptoms.
Viral Classification and Criteria
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Criteria for classifying viruses: Size, nucleic acid type (DNA or RNA), morphology, physical/chemical properties, symmetry, genome features, mode of transmission, animal susceptibility, place of isolation, pathogenicity, replication.
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Families and orders for viral classification and suffix naming conventions.
Viral Families (Examples)
- DNA families listed.
- RNA families listed.
Viral Order
- Mononegavirales: Includes viruses with single-stranded, negative-sense, and unsegmented RNA. Examples include Filoviridae (Ebolavirus), Rhabdoviridae (Rabies virus), and Paramyxoviridae (Parainfluenza virus).
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Description
Test your knowledge of virus transmission methods with this engaging quiz! Explore different types of transmission, including respiratory, zoonotic, and bloodborne, and identify key characteristics of various viruses. Perfect for students of virology and infectious diseases.
