Human rotaviruses are characterized by which of the following statements?
**Core Concept**
Human rotaviruses are a major cause of severe gastroenteritis in infants and young children worldwide. They belong to the family Reoviridae and are characterized by their unique triple-layered icosahedral capsid structure, which protects the viral genome.
**Why the Correct Answer is Right**
Human rotaviruses are non-enveloped viruses with a segmented double-stranded RNA genome. The triple-layered capsid consists of an outer capsid made of VP7 (glycoprotein) and VP4 (protease-sensitive protein), a middle layer of VP6 (core protein), and an inner core composed of VP1, VP2, and VP3. This complex structure allows the virus to attach to and penetrate the host cells, leading to the replication and release of new virus particles.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because human rotaviruses are not enveloped viruses, unlike some other viruses that have a lipid membrane surrounding their capsid.
**Option B:** This option is incorrect because while rotaviruses do have a segmented genome, it is composed of double-stranded RNA, not single-stranded RNA.
**Option C:** This option is incorrect because the capsid of human rotaviruses is not made of a single protein, but rather a combination of multiple proteins (VP7, VP4, VP6, VP1, VP2, and VP3).
**Clinical Pearl / High-Yield Fact**
Human rotaviruses are highly contagious and can be spread through fecal-oral contact, contaminated food and water, and close contact with an infected individual. Vaccination is an effective way to prevent rotavirus infection and its associated severe gastroenteritis.
**Correct Answer: C. They have a triple-layered icosahedral capsid structure.**