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Questions and Answers
What is the primary site of replication for RNA viruses?
What is the primary site of replication for RNA viruses?
Which of these categories best describes RNA viruses?
Which of these categories best describes RNA viruses?
What method of viral transmission involves bites from animals?
What method of viral transmission involves bites from animals?
Which of the following viruses is transmitted through fecal-oral routes?
Which of the following viruses is transmitted through fecal-oral routes?
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What is a distinguishing feature of bacteriophages?
What is a distinguishing feature of bacteriophages?
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What is Tecovirimat (TPOXX) primarily used for?
What is Tecovirimat (TPOXX) primarily used for?
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Which groups are at increased risk of severe RSV?
Which groups are at increased risk of severe RSV?
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How long can individuals infected with RSV be infectious?
How long can individuals infected with RSV be infectious?
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What is a common symptom associated with Respiratory Syncytial Virus (RSV)?
What is a common symptom associated with Respiratory Syncytial Virus (RSV)?
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When does the RSV season typically begin?
When does the RSV season typically begin?
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What is the recommended treatment for managing fever and pain associated with RSV?
What is the recommended treatment for managing fever and pain associated with RSV?
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What seasonal pattern is noted for RSV in Florida compared to other regions?
What seasonal pattern is noted for RSV in Florida compared to other regions?
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Which statement about RSV and its transmission is true?
Which statement about RSV and its transmission is true?
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What is the primary function of a viral capsid?
What is the primary function of a viral capsid?
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Which of the following statements about RNA viruses is true?
Which of the following statements about RNA viruses is true?
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What characteristic about viral envelopes contributes to their instability?
What characteristic about viral envelopes contributes to their instability?
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How do DNA viruses typically lead to the production of proteins?
How do DNA viruses typically lead to the production of proteins?
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Which of the following sizes correctly represents the diameter of most viruses?
Which of the following sizes correctly represents the diameter of most viruses?
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What differentiates positive-stranded RNA viruses from negative-stranded RNA viruses?
What differentiates positive-stranded RNA viruses from negative-stranded RNA viruses?
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Which of the following is NOT a characteristic of viruses?
Which of the following is NOT a characteristic of viruses?
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What is a nucleocapsid?
What is a nucleocapsid?
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Which type of viruses typically have both negative and positive strands of DNA?
Which type of viruses typically have both negative and positive strands of DNA?
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What type of viral structure is always enveloped?
What type of viral structure is always enveloped?
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What is a primary method of transmission for COVID-19?
What is a primary method of transmission for COVID-19?
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Which COVID-19 symptom is characterized by a severe overproduction of cytokines?
Which COVID-19 symptom is characterized by a severe overproduction of cytokines?
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What is the likely origin of the COVID-19 virus?
What is the likely origin of the COVID-19 virus?
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Which of the following is NOT a risk factor for severe COVID-19 outcomes?
Which of the following is NOT a risk factor for severe COVID-19 outcomes?
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What characterizes the reproduction method of viruses?
What characterizes the reproduction method of viruses?
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What type of coronavirus primarily causes the common cold?
What type of coronavirus primarily causes the common cold?
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Which test is the most sensitive for diagnosing COVID-19?
Which test is the most sensitive for diagnosing COVID-19?
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What is the mortality rate for MERS-CoV infections?
What is the mortality rate for MERS-CoV infections?
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What is a symptom of 'Long COVID' experienced by patients post-infection?
What is a symptom of 'Long COVID' experienced by patients post-infection?
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What protein does SARS-CoV-2 use to attach to human cells?
What protein does SARS-CoV-2 use to attach to human cells?
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How long after vaccination does full protection occur for JYNNEOS against monkeypox?
How long after vaccination does full protection occur for JYNNEOS against monkeypox?
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What is a common symptom of the 'common cold' caused by coronaviruses?
What is a common symptom of the 'common cold' caused by coronaviruses?
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Which statement about the PCR test is correct?
Which statement about the PCR test is correct?
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What treatment approach is indicated for patients diagnosed with COVID-19 'Long COVID'?
What treatment approach is indicated for patients diagnosed with COVID-19 'Long COVID'?
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Study Notes
Introduction to Viruses
- Viruses are infectious, obligate intracellular parasites.
- They consist of genetic material (DNA or RNA) enclosed in a protein coat (capsid).
- Some viruses have an additional lipid envelope derived from host cells.
Learning Objectives
- Compare and contrast viruses with other cell forms.
- Describe properties of viruses, including their molecular structure, composition, and replication strategies.
- Recognize the differences between DNA and RNA viruses.
Virus Structure
- Viruses are simple structures.
- They consist of a capsid surrounding genetic material.
- A nucleocapsid is composed of nucleic acid genome and capsid proteins.
- Some viruses are enveloped, having a lipid bilayer membrane with viral proteins.
Properties of Viruses
- Viruses lack cellular machinery to synthesize proteins.
- Viruses are obligate intracellular parasites.
- Viruses don't have energy source like ATP.
- Viruses do not have ribosomes or organelles.
- Viruses cannot perform metabolic processes independently.
Virus Size
- Viruses vary in size.
- DNA viruses, RNA viruses and bacteriophages are different sizes.
- Viruses are much smaller than bacteria or human cells.
- Their dimensions are measured in nanometers (nm).
Virus Shape
- Capsid: The protein coat surrounding the virus genome; composed of repeating subunits called capsomeres
- Nucleocapsid: The structure composed of the nucleic acid genome and the capsid proteins.
- Icosahedral: Capsomers arranged in triangles, forming a spherical shape; can be enveloped or naked
- Helical: Capsomers arranged in a hollow coil, forming a rod-shaped structure; always enveloped
Viral Envelopes
- Derived from host cell membranes.
- Contain glycoproteins that attach to host receptors.
- Make viruses more sensitive to heat, drying, detergents, and lipid solvents
- Viruses lose their stability when their envelopes are removed
Virus Composition
- Nucleic acid: DNA or RNA; can be single- or double-stranded, linear or circular, or segmented.
- Proteins: Provide structure and functions like protecting the genome, facilitating transfer, attachment, and acting as antigens.
- Genetic material is either DNA or RNA, single or double stranded, linear or circular or segmented
RNA Viruses
- Genetic material is RNA.
- Single-stranded, either (+) or (-)
- Classification is by the type and function of the RNA.
- Replication occurs in the cytoplasm.
- Most are enveloped
RNA Virus Polarity
- Positive (+) stranded RNA viruses: act directly as mRNA in the process of translation.
- Negative (-) stranded RNA viruses: not directly translatable, need to be converted to (+) stranded RNA.
- Most RNA viruses do have RNA polymerase in their capsid.
DNA Viruses
- Genetic material is DNA.
- Double-stranded.
- Replication occurs in the nucleus
- Most have negative (-) and positive (+) strand
- Must be transcribed into mRNA; then translated into structural proteins and enzymes
DNA vs. RNA Viruses
- RNA viruses are single-stranded and have helical symmetry (may or may not have envelopes), replicating in the cytoplasm.
- DNA viruses are double-stranded and have icosahedral symmetry (may or may not have envelopes), replicating in the nucleus.
- DNA viruses tend to be genetically complex compared to RNA viruses.
Viral Transmission and Replication
- Direct transmission: Person-to-person contact (no fomites)
- Indirect transmission: Inanimate objects (fomites)
- Animal-to-animal: with humans as an accidental host
- Arthropod vector transmission
Bacteriophages
- Viruses that infect bacteria.
- Frequently used for phage therapy targeting specific bacteria.
Specific Outbreaks (e.g. SARS-CoV, MERS-CoV, COVID-19, Monkeypox, RSV)
- Specific characteristics, origins, transmission, clinical findings.
- COVID-19 pandemic, including clinical findings, long-COVID, and treatments, vaccination.
- Monkeypox outbreak, including symptoms, transmission, diagnosis, treatments and vaccination.
- RSV epidemiology. Symptoms and treatment options.
Virus Taxonomy
- The scientific classification of viruses follows a hierarchical system, including family, subfamily, genus and species names, using suffixes.
Coronavirus
- Relatively large viral particles
- Non-segmented, single-stranded RNA
- Enveloped with helical nucleocapsid
- Prominent spike proteins
COVID-19 Clinical Findings
- Varying clinical features; Incubation periods, symptoms.
COVID-19 Risk Factors
- Older adults (especially over 70)
- Co-morbidities (compromised immunity, diabetes, chronic heart, kidney, or respiratory disease.)
- Obese patients (especially BMI over 30)
- Smoking or vaping history
- Gender considerations and factors relating to infection rates.
COVID-19 Outpatient Treatments
- Recommended medications and clinical indications for certain use cases.
- Hospitalization and outpatient treatment preferences.
COVID-19: "Long COVID"
- Persistence of symptoms after initial infection
- Variety of symptoms, including cognitive difficulties, fatigue, dyspnea, insomnia, and impaired daily functioning; disproportionality affecting women
COVID-19 Vaccine Schedules
- mRNA vaccines are preferred, with bivalent boosters becoming available for certain timeframes.
- Vaccinations may be given to different age groups, and at different timeframes from initial infection or other vaccination.
MPOX
- Orthopoxvirus, endemic to Africa.
- Most common in Men who have sex with Men (MSM).
- Direct contact with rash and scabs; contact with saliva and upper respiratory secretions.
- Not strictly sexually transmitted
RSV
- Respiratory syncytial virus, affecting respiratory tracts; resulting in various levels of severity.
- Epidemiology information, seasonal pattern, prevalence.
Virus Diagnosis
- PCR testing for viral RNA or antigen testing.
- Serum antibody tests to detect immunity level.
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Description
Explore the fascinating world of viruses, their structures, properties, and replication strategies. This quiz will help you compare viruses with other cell forms and distinguish between DNA and RNA viruses. Test your knowledge about these obligate intracellular parasites and their complex nature.
