Which family of viruses is composed of double-stranded DNA, enveloped, icosahedral viruses?

• A. Adenoviridae
• B. Herpesviridae
• C. Picornaviridae
• D. Orthomyxoviridae

Answer: (B)

Understanding how viruses are categorized helps you pick the right family from the clues: genome type, presence of an envelope, and capsid shape. Among these options, the family that has double-stranded DNA, is enveloped, and has an icosahedral capsid fits herpesviruses. The herpesviridae are large enveloped DNA viruses with a characteristic icosahedral capsid and latent infection capabilities, including well-known members like herpes simplex virus, varicella-zoster virus, cytomegalovirus, and Epstein-Barr virus.

In contrast, adenoviridae also have double-stranded DNA but lack an envelope, picornaviridae are single-stranded RNA and nonenveloped, and orthomyxoviridae are enveloped but contain negative-sense RNA and a helical rather than icosahedral arrangement.