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Questions and Answers
What is the primary structural feature that distinguishes enveloped viruses from naked viruses?
What is the primary structural feature that distinguishes enveloped viruses from naked viruses?
Which type of virus has a flexible and coiled nucleocapsid within its envelope?
Which type of virus has a flexible and coiled nucleocapsid within its envelope?
Which group of viruses includes the hepatitis B virus?
Which group of viruses includes the hepatitis B virus?
What type of genetic material do papovaviruses contain?
What type of genetic material do papovaviruses contain?
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What term describes the viruses that do not have an envelope?
What term describes the viruses that do not have an envelope?
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Which of the following is NOT a characteristic of enveloped viruses?
Which of the following is NOT a characteristic of enveloped viruses?
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What is the major method of classifying medically important viruses?
What is the major method of classifying medically important viruses?
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Which of the following viruses is associated with kidney transplant patients?
Which of the following viruses is associated with kidney transplant patients?
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Which type of virus is associated with the Pfizer-BioNTech COVID-19 vaccine?
Which type of virus is associated with the Pfizer-BioNTech COVID-19 vaccine?
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What is the classification of parvoviruses based on their DNA structure?
What is the classification of parvoviruses based on their DNA structure?
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Which of the following vaccines uses a viral vector platform?
Which of the following vaccines uses a viral vector platform?
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How are RNA viruses primarily classified?
How are RNA viruses primarily classified?
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Which virus family has double-stranded RNA as its genome?
Which virus family has double-stranded RNA as its genome?
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Which COVID-19 vaccine is categorized as protein-based?
Which COVID-19 vaccine is categorized as protein-based?
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What is a key characteristic of adenoviruses in relation to their genome and structure?
What is a key characteristic of adenoviruses in relation to their genome and structure?
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Which of the following statements about influenza viruses is true?
Which of the following statements about influenza viruses is true?
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What are the two main types of viral genomes based on their nucleic acid structure and polarity?
What are the two main types of viral genomes based on their nucleic acid structure and polarity?
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What type of symmetry is associated with capsids that consist of several different polypeptides?
What type of symmetry is associated with capsids that consist of several different polypeptides?
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Which component is found in the nucleocapsid of viruses with helical symmetry?
Which component is found in the nucleocapsid of viruses with helical symmetry?
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What are the two essential components that make up a virus?
What are the two essential components that make up a virus?
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What distinguishes positive-strand RNA viruses from negative-strand RNA viruses?
What distinguishes positive-strand RNA viruses from negative-strand RNA viruses?
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Which of the following characteristics does NOT differentiate virus families?
Which of the following characteristics does NOT differentiate virus families?
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How is the pathogenicity of a virus primarily determined?
How is the pathogenicity of a virus primarily determined?
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What is the structural composition of icosahedral capsids?
What is the structural composition of icosahedral capsids?
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How do helical capsids assemble their structure?
How do helical capsids assemble their structure?
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What is the size range of viruses compared to the cells they infect?
What is the size range of viruses compared to the cells they infect?
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What type of viral capsid symmetry can viruses have?
What type of viral capsid symmetry can viruses have?
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What structural role do capsomers play in icosahedral symmetry?
What structural role do capsomers play in icosahedral symmetry?
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Which of the following properties helps in the classification of viruses into genera and species?
Which of the following properties helps in the classification of viruses into genera and species?
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Which of the following statements about the virion is incorrect?
Which of the following statements about the virion is incorrect?
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What is the purpose of the lipid envelope in certain viruses?
What is the purpose of the lipid envelope in certain viruses?
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Which size attribute differentiates virions from bacteria?
Which size attribute differentiates virions from bacteria?
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What is a notable feature of hepadnaviruses?
What is a notable feature of hepadnaviruses?
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Which of the following is a human pathogen in the herpesvirus family?
Which of the following is a human pathogen in the herpesvirus family?
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What distinguishes poxviruses from other virus families?
What distinguishes poxviruses from other virus families?
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Which family of viruses is noted for causing latent infections?
Which family of viruses is noted for causing latent infections?
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What is the diameter of picornaviruses?
What is the diameter of picornaviruses?
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What is the virus responsible for COVID-19?
What is the virus responsible for COVID-19?
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What is a primary mode of transmission for MERS to humans?
What is a primary mode of transmission for MERS to humans?
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Which of the following viruses is part of the picornavirus family?
Which of the following viruses is part of the picornavirus family?
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Which of the following is a common symptom of COVID-19?
Which of the following is a common symptom of COVID-19?
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What type of RNA do caliciviruses carry?
What type of RNA do caliciviruses carry?
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What proportion of people with COVID-19 develop serious illness requiring medical attention?
What proportion of people with COVID-19 develop serious illness requiring medical attention?
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When was COVID-19 declared a pandemic by WHO?
When was COVID-19 declared a pandemic by WHO?
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Which animal is thought to be a reservoir for MERS coronavirus?
Which animal is thought to be a reservoir for MERS coronavirus?
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What is the average incubation period for COVID-19?
What is the average incubation period for COVID-19?
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Which group is more likely to develop serious illness from COVID-19?
Which group is more likely to develop serious illness from COVID-19?
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Study Notes
Medical Important Viruses
- Viruses are infectious agents.
- They are minimally constructed of two components: a genome (RNA or DNA, but not both) and a protein-containing structure (capsid).
- Some viruses also have an envelope composed of a protein-containing lipid bilayer.
- A complete virus particle is called a virion
- Viruses replicate inside host cells.
- Viral replication is a process that is obligately intracellular.
- Pathogenicity of a virus depends on several structural and functional characteristics.
- Viruses are classified into families, genera, and species based on characteristics like genome type, replication strategy, capsid symmetry, and presence or absence of an envelope.
Virus Structure
- Viruses are significantly smaller than cells (100-1000 fold)
- Smallest viruses have a diameter of 20 nm, while the largest are approximately 300 nm in diameter.
- Viruses can pass through filters designed to trap bacteria.
Virus Genome
- Viral genomes can be DNA or RNA, single-stranded (ss) or double-stranded (ds).
- The most common forms are ssRNA and dsDNA.
- Single-stranded viral RNA genomes are further subdivided into those with positive or negative polarity.
- Positive-polarity RNA genomes can directly be used as a template for protein synthesis.
- Negative-polarity RNA genomes must first be converted into positive-polarity RNA before they can be used as a template.
Capsid Symmetry
- The protein shell enclosing the genome is called the capsid.
- Capsids can be helical or icosahedral.
- Helical capsids are rod-shaped or coiled.
- Icosahedral capsids are spherical or symmetrical.
- A capsid is constructed of multiple copies of one or few polypeptide types or a single polypeptide type.
Envelope
- Viruses may or may not have an envelope.
- An envelope is a lipid-containing membrane that surrounds the nucleocapsid.
- Enveloped viruses are more fragile and sensitive to various environmental factors compared to naked viruses.
- Envelopes are often derived from host cell membranes and contain virus-specific proteins.
Viral Replication
- Viral replication involves several steps, including attachment to host cells, penetration and uncoating of the viral genome, gene expression and replication, assembly of new viral particles, and release of viral progeny.
Baltimore Classification
- Viruses are classified into seven groups based on the nature of their genomic RNA or DNA sequence. These seven groups allow for more accurate and systematic classification of medically important viruses.
Papovaviruses
- Naked icosahedral viruses with double-stranded circular DNA.
- Includes viruses implicated in human diseases, like BK virus and HPV.
Adenoviruses
- Naked icosahedral viruses with double-stranded linear DNA.
- Associated with various respiratory tract infections.
Hepadnaviruses
- Enveloped icosahedral viruses with partially double-stranded DNA.
- Hepatitis B virus is the most notable pathogen.
Herpesviruses
- Enveloped viruses with double-stranded linear DNA.
- Cause latent infections, leading to recurrent infections.
Poxviruses
- Enveloped DNA viruses with a brick-like shape and complex capsid.
- Associated with diseases such as smallpox and monkeypox.
RNA Viruses
- A wide variety of RNA viruses exist, each with distinct categories for their single-stranded or double-stranded RNA genomes, if segmented or nonsegmented, and also if positive or negative polarity.
Coronaviruses
- Enveloped, icosahedral RNA viruses.
- Coronavirus diseases such as SARS, MERS, COVID-19.
Other RNA Viruses
- Information on other RNA viruses (Togaviruses, Orthomyxoviruses, Paramyxoviruses, Rhabdoviruses, Filoviruses.
Diseases
- Coronaviruses are associated with several diseases, including the common cold, SARS, MERS, and COVID-19.
Prevention
- Washing hands frequently, avoiding contact with sick people, wearing a mask, and avoiding crowded places are some methods to prevent COVID-19 transmission.
Molecular Tests
- Methods of diagnosis of active SARS-CoV-2 infections, including nucleic acid detection and antibody detection.
Vaccines
- Several COVID-19 vaccines are available, including mRNA vaccines, inactivated virus vaccines, and viral vector vaccines.
- Vaccination is a proven method for disease prevention.
Variants
- SARS-CoV-2 has multiple variants (e.g., Alpha, Beta, Gamma, and Delta).
- These variants might show differing degrees of transmission, disease severity, and vaccine effectiveness.
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Description
Test your knowledge on enveloped and naked viruses, their structural features, and classification methods. This quiz covers various types of viruses, including those associated with vaccines and specific diseases. Perfect for students studying virology or microbiology!
