Ch. 25 - Pathogenic RNA Viruses

Bauman - Microbiology with Diseases by Taxonomy 6th Edition

Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302Not the one you use?Change textbook

Bauman 6th Edition

Ch. 25 - Pathogenic RNA Viruses

Problem 2

Chapter 25, Problem 2

What do viruses in the families Picornaviridae, Caliciviridae, Astroviridae, Coronaviridae, Togaviridae, Flaviviridae, and Retroviridae have in common?

a. They are arboviruses.
b. They are nonpathogenic.
c. They have positive single-stranded RNA genomes.
d. They have negative single-stranded RNA genomes.

Verified step by step guidance

Step 1: Identify the key characteristic to compare among the virus families Picornaviridae, Caliciviridae, Astroviridae, Coronaviridae, Togaviridae, Flaviviridae, and Retroviridae. The question asks what they have in common regarding their genome type or other features.

Step 2: Recall that viruses are classified based on their genome type: DNA or RNA, single-stranded or double-stranded, and if RNA, whether it is positive-sense (+ssRNA) or negative-sense (-ssRNA).

Step 3: Review the genome type of each virus family: Picornaviridae, Caliciviridae, Astroviridae, Coronaviridae, Togaviridae, Flaviviridae, and Retroviridae are all known to have single-stranded RNA genomes. Specifically, most of these families have positive-sense single-stranded RNA genomes.

Step 4: Understand the terms: 'arboviruses' are viruses transmitted by arthropods (like mosquitoes), 'nonpathogenic' means they do not cause disease, and 'positive' or 'negative' single-stranded RNA refers to the polarity of the RNA genome, which affects how the virus replicates.

Step 5: Conclude that the common feature among these virus families is that they all have positive single-stranded RNA genomes, which corresponds to option (c).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Virus Genome Types

Viruses can have different types of genetic material, including DNA or RNA, which can be single-stranded or double-stranded, and positive-sense or negative-sense. Positive single-stranded RNA (+ssRNA) viruses have genomes that can directly serve as mRNA for protein synthesis, while negative single-stranded RNA (-ssRNA) viruses must first be transcribed into positive-sense RNA.

Families of RNA Viruses

The virus families Picornaviridae, Caliciviridae, Astroviridae, Coronaviridae, Togaviridae, Flaviviridae, and Retroviridae are all known to contain viruses with positive-sense single-stranded RNA genomes. This commonality influences their replication strategies and pathogenic mechanisms.

Arboviruses and Pathogenicity

Arboviruses are viruses transmitted by arthropods like mosquitoes and ticks, but not all viruses in the listed families are arboviruses. Additionally, these viruses are generally pathogenic, causing diseases in humans or animals, so the options stating they are all arboviruses or nonpathogenic are incorrect.

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Textbook Question

Why are humans considered “dead-end” hosts for many arboviruses?

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Textbook Question

Young Luis has skin lesions. His mother knows from microbiology class that five childhood diseases can produce spots. Name those five diseases and the viruses that cause each. List some questions to ask to determine which of these viruses Luis has.

Textbook Question

What viral family causes each of these diseases? (A family may be used more than once.)

1. _____Myocarditis

2. _____Colorado tick fever

3. _____Rabies

4. _____Influenza

5. _____Dengue fever

6. _____German measles

7. _____Acute gastroenteritis

8. _____Ebola virus

9. _____RSV

10. _____Western equine encephalitis