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

1. Step 1: Identify the key characteristic of each virus family listed: Picornaviridae, Caliciviridae, Astroviridae, Coronaviridae, Togaviridae, Flaviviridae, and Retroviridae. These families are known for their genome type and structure.
2. Step 2: Recall that viruses can have either DNA or RNA genomes, and RNA viruses can be either positive-sense (+ssRNA) or negative-sense (-ssRNA). Understanding the difference is crucial: positive-sense RNA can be directly translated into proteins, while negative-sense RNA must be transcribed into positive-sense RNA first.
3. Step 3: Review the genome type of each family: Picornaviridae, Caliciviridae, Astroviridae, Coronaviridae, Togaviridae, Flaviviridae, and Retroviridae are all known to have positive single-stranded RNA genomes.
4. Step 4: Evaluate the options: (a) arboviruses are viruses transmitted by arthropods, but not all listed families are arboviruses; (b) nonpathogenic means not causing disease, which is not true for all these viruses; (c) positive single-stranded RNA genomes matches the known genome type; (d) negative single-stranded RNA genomes is incorrect for these families.
5. Step 5: Conclude that the common feature among these virus families is that they all have positive single-stranded RNA genomes.

Key Concepts

Virus Genome Types

Viruses can have different types of genetic material, including DNA or RNA, which can be single-stranded or double-stranded. Understanding whether a virus has positive-sense or negative-sense RNA is crucial, as it affects how the virus replicates and translates its proteins inside host cells.

Positive-Sense Single-Stranded RNA Viruses

Positive-sense single-stranded RNA (+ssRNA) viruses have genomes that can directly serve as messenger RNA (mRNA) for protein synthesis. This means their RNA can be immediately translated by the host's ribosomes upon infection, facilitating rapid viral replication.

Virus Family Characteristics

Each virus family, such as Picornaviridae or Retroviridae, is classified based on shared structural and genetic features. Many families listed, including Picornaviridae, Caliciviridae, Astroviridae, Coronaviridae, Togaviridae, Flaviviridae, and Retroviridae, are known to have positive-sense single-stranded RNA genomes, which is a key unifying trait.