Question

Which of these is a calicivirus?

• A. HAV
• B. HBV
• C. HCV
• D. HEV

Hint:

HEV was historically grouped with Caliciviridae due to its size and shape, though it is now placed in its own family, Hepeviridae.

Answer 1

The Correct Option is D

Step 1: Sort the four hepatitis viruses by family.
Hepatitis A virus (HAV) belongs to the Picornaviridae family, in the genus Hepatovirus, and is a small non-enveloped RNA virus.
Hepatitis B virus (HBV) belongs to the Hepadnaviridae family, and is unusual because it is a DNA virus that replicates through an RNA intermediate.
Hepatitis C virus (HCV) belongs to the Flaviviridae family, the same family as dengue and yellow fever virus.

Step 2: Place Hepatitis E virus.
Hepatitis E virus (HEV) is a small, non-enveloped, single-stranded RNA virus spread by the fecal-oral route, much like Hepatitis A, and it was traditionally taught as a member of the Caliciviridae family because of its similar size and shape on electron microscopy. This classification is why textbooks from this exam's era list HEV as the calicivirus among the hepatitis viruses.

Step 3: Note the current classification (update).
Later molecular and genomic studies showed HEV's genome organisation is different enough from true caliciviruses that it has since been moved into its own family, Hepeviridae (genus Orthohepevirus), and it is no longer officially classified as a calicivirus. This is a reclassification, not a change in which virus causes Hepatitis E; the exam-era answer among these four options remains HEV, since none of HAV, HBV or HCV was ever grouped with caliciviruses.

Final Answer:
Among the given options, Hepatitis E virus is the one historically classified as a calicivirus.
\[ \boxed{\text{HEV}} \]