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Questions and Answers
What factors contribute to the classification of viruses into genera and species?
What factors contribute to the classification of viruses into genera and species?
What distinguishes positive-strand RNA viruses from negative-strand RNA viruses?
What distinguishes positive-strand RNA viruses from negative-strand RNA viruses?
What geometric configuration characterizes helical symmetry in virus capsids?
What geometric configuration characterizes helical symmetry in virus capsids?
Which of the following best describes the composition of icosahedral capsids?
Which of the following best describes the composition of icosahedral capsids?
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What is the primary function of the capsid in a virus?
What is the primary function of the capsid in a virus?
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What term describes the complex of protomers and nucleic acid within helical capsids?
What term describes the complex of protomers and nucleic acid within helical capsids?
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What is a common property of single-stranded RNA genomes that have positive polarity?
What is a common property of single-stranded RNA genomes that have positive polarity?
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What defines the stability and shape of an icosahedral virus capsid?
What defines the stability and shape of an icosahedral virus capsid?
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Which viruses are known to cause respiratory infections in humans?
Which viruses are known to cause respiratory infections in humans?
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What is the primary human pathogen associated with Rhabdoviruses?
What is the primary human pathogen associated with Rhabdoviruses?
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Which of the following statements is true regarding Filoviruses?
Which of the following statements is true regarding Filoviruses?
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What type of RNA do Coronaviruses have?
What type of RNA do Coronaviruses have?
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Which virus emerged in 2012 causing severe pneumonia?
Which virus emerged in 2012 causing severe pneumonia?
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What is the estimated fatality rate for SARS as reported?
What is the estimated fatality rate for SARS as reported?
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Which animal is identified as the natural reservoir for SARS-CoV?
Which animal is identified as the natural reservoir for SARS-CoV?
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What characteristic shape do Rhabdoviruses exhibit?
What characteristic shape do Rhabdoviruses exhibit?
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What is the primary characteristic that differentiates adenoviruses from hepadnaviruses?
What is the primary characteristic that differentiates adenoviruses from hepadnaviruses?
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Which of the following viruses is known for causing latent infections?
Which of the following viruses is known for causing latent infections?
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What type of genome do picornaviruses possess?
What type of genome do picornaviruses possess?
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Which viral family is associated with skin lesions known as 'pocks'?
Which viral family is associated with skin lesions known as 'pocks'?
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What is unique about the DNA of hepadnaviruses compared to other DNA viruses?
What is unique about the DNA of hepadnaviruses compared to other DNA viruses?
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Which of the following viruses is classified as an enveloped virus?
Which of the following viruses is classified as an enveloped virus?
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Which of these statements about caliciviruses is true?
Which of these statements about caliciviruses is true?
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What is the primary disease associated with the hepatitis B virus?
What is the primary disease associated with the hepatitis B virus?
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What is the main structural feature that distinguishes enveloped viruses from naked viruses?
What is the main structural feature that distinguishes enveloped viruses from naked viruses?
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Which group of viruses is classified under the Baltimore classification system as (-)ssRNA?
Which group of viruses is classified under the Baltimore classification system as (-)ssRNA?
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What is the significance of the virus-specific proteins in enveloped viruses?
What is the significance of the virus-specific proteins in enveloped viruses?
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Which of the following viruses is classified as a naked icosahedral virus?
Which of the following viruses is classified as a naked icosahedral virus?
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What happens during the assembly step in the virus replication cycle?
What happens during the assembly step in the virus replication cycle?
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How do naked viruses differ in terms of their susceptibility to environmental conditions compared to enveloped viruses?
How do naked viruses differ in terms of their susceptibility to environmental conditions compared to enveloped viruses?
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Which class of viruses includes the human papillomavirus?
Which class of viruses includes the human papillomavirus?
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What is the common feature of the three naked icosahedral virus families mentioned?
What is the common feature of the three naked icosahedral virus families mentioned?
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What is the primary mode of transmission for MERS to humans?
What is the primary mode of transmission for MERS to humans?
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What is the incubation period for COVID-19?
What is the incubation period for COVID-19?
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What is the correct virus strain responsible for COVID-19?
What is the correct virus strain responsible for COVID-19?
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What percentage of people is expected to recover from COVID-19 without special treatment?
What percentage of people is expected to recover from COVID-19 without special treatment?
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Which of the following symptoms is NOT commonly associated with COVID-19?
Which of the following symptoms is NOT commonly associated with COVID-19?
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Who is more likely to develop severe illness from COVID-19?
Who is more likely to develop severe illness from COVID-19?
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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 of the following statements about MERS is true?
Which of the following statements about MERS is true?
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Which of the following vaccines uses a protein-based platform?
Which of the following vaccines uses a protein-based platform?
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What type of virus classification is primarily based on the presence of an envelope and the nature of the genome?
What type of virus classification is primarily based on the presence of an envelope and the nature of the genome?
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Which RNA virus family is characterized by having double-stranded RNA?
Which RNA virus family is characterized by having double-stranded RNA?
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Which of the following vaccines is administered as a single dose?
Which of the following vaccines is administered as a single dose?
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What describes parvoviruses in terms of genomic structure?
What describes parvoviruses in terms of genomic structure?
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Which of the following platforms does the Pfizer-BioNTech COVID-19 vaccine utilize?
Which of the following platforms does the Pfizer-BioNTech COVID-19 vaccine utilize?
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Which virus family is known for having positive-polarity RNA?
Which virus family is known for having positive-polarity RNA?
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Which COVID-19 vaccine is developed using an inactivated virus platform?
Which COVID-19 vaccine is developed using an inactivated virus platform?
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Study Notes
Medical Important Viruses
- Viruses are infectious agents with a minimal structure.
- They consist of a genome (RNA or DNA, but not both) and a protein capsid.
- Some viruses have an additional envelope composed of lipids and protein.
- A complete virus particle is called a virion.
- Viruses rely on host cells for replication.
- Viral pathogenicity varies greatly.
- Viruses are much smaller than cells (100-1000 times smaller)
- Viruses can pass through filters designed to trap bacteria.
Virus Structure
- Viruses vary in size, from 20nm to 300nm.
- Simple viruses have a nucleocapsid (capsid and nucleic acid).
- Enveloped viruses have a lipid envelope surrounding the capsid.
- The capsid may have helical or icosahedral symmetry.
- Parts of a virus include capsid, core, nucleic acid, and spikes (attachment).
Virus Replication
- Viral replication occurs in the host cell.
- Stages include attachment, penetration, uncoating of viral genome, replication, assembly, and release of viral progeny.
- Viral replication strategy depends on the specific virus.
Viral Genome
- Viral genomes can be DNA or RNA
- They can be single- or double-stranded, linear or circular.
- RNA viruses can be positive or negative polarity (sense or antisense).
Viral Capsid Symmetry
- Capsids for most viruses have either helical or icosahedral symmetry.
- The structure is created from a limited number of genetic and structural components within the genome.
Viral Envelopes
- Many but not all viruses are enveloped.
- Envelopes are derived from host cell membranes, but have protein substituted for some host cell components, giving the virus unique features.
- Viruses lacking envelopes are called naked viruses.
Viral Families, Genera, and Species
- Viruses are categorized into families, subfamilies, genera, and species.
- Classification is based on:
- Viral nucleic acid type and structure
- Replication strategy
- Capsid symmetry (helical or icosahedral)
- Presence or absence of an envelope.
Baltimore Classification
- A system for classifying viruses based on their genome type (DNA or RNA) and mode of replication.
- There are seven groups based on how they make mRNA.
Specific Viral Families
- Papovaviruses: Naked, icosahedral DNA viruses. Examples include HPV, BK virus, JC virus.
- Adenoviruses: Naked, icosahedral DNA viruses. Cause respiratory infections, and can cause some tumors in animals.
- Hepadnaviruses: Enveloped, icosahedral DNA viruses, with some DNA partially single-stranded. Examples include Hepatitis B virus
- Herpesviruses: Enveloped DNA viruses, causing numerous infections. Examples include Herpes simplex viruses, Varicella zoster virus, Epstein-Barr virus, and cytomegalovirus.
- Poxviruses: Large, brick-shaped DNA viruses with a complex internal structure. Examples include smallpox and monkeypox viruses.
- Picornaviruses: Small, naked viruses with positive single-stranded RNA genomes. Examples include poliovirus, rhinovirus, hepatitis A virus.
- Caliciviruses: Naked, positive single-stranded RNA viruses. Cause gastroenteritis (e.g., Norwalk virus)
- Reoviruses: Naked, double-stranded RNA viruses with segmented genomes. Examples include rotavirus
- Flaviviruses: Enveloped, positive single-stranded RNA viruses. Examples include yellow fever virus, dengue virus, West Nile virus.
- Togaviruses: Enveloped, positive single-stranded RNA viruses. Examples include rubella virus, and alphaviruses.
- Retroviruses: Enveloped, single-stranded RNA viruses that reverse-transcribe their RNA into DNA using reverse transcriptase. Examples include HIV-1 and HIV-2.
- Orthomyxoviruses: Enveloped, segmented negative-stranded RNA viruses. Examples include influenza viruses.
- Paramyxoviruses: Enveloped, non-segmented negative-stranded RNA viruses. Examples include measles virus, mumps virus, parainfluenza viruses.
- Rhabdoviruses: Enveloped, single-stranded RNA viruses, typically bullet-shaped. Examples include rabies virus.
- Filoviruses: Enveloped, single-stranded RNA viruses. Examples include Ebola virus and Marburg virus.
- Coronaviruses: Enveloped, positive single-stranded RNA viruses with a crown-like spike protein on their surface; Examples include SARS-CoV, MERS-CoV, and SARS-CoV-2
Diseases
- Coronaviruses cause the common cold and serious diseases like SARS, MERS, and COVID-19.
- Viral diseases can cause mild to severe symptoms depending on the pathogen.
Virology Testing and Prevention
- Molecular tests (e.g., PCR) detect viral RNA.
- Antibody tests (serology) detect the immune response to the virus.
- Effective preventive measures include vaccination and hygiene practices.
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Description
Test your knowledge on the structure, replication, and pathogenicity of important viruses. This quiz covers essential facts about viruses, including their anatomy and lifecycle. Dive into the microscopic world of these infectious agents and check your understanding!
