Which statement is correct concerning animal viruses?

• A. Animal viruses replicate only in the cytoplasm of host cells.
• B. Animal viruses cannot cause latent infections.
• C. Animal viruses always have a cell wall.
• D. Animal viruses may enter host cells by endocytosis or membrane fusion.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the structure and replication sites of animal viruses. Animal viruses can replicate in the cytoplasm or the nucleus of the host cell, depending on the type of virus. For example, DNA viruses often replicate in the nucleus, while RNA viruses typically replicate in the cytoplasm.
2. Step 2: Review the concept of latent infections. Latent infections occur when a virus remains dormant within the host cell without causing immediate lysis or symptoms. Many animal viruses, such as herpesviruses, are capable of establishing latent infections.
3. Step 3: Consider the structural components of animal viruses. Unlike bacteria, animal viruses do not have a cell wall. Instead, they have a protein coat called a capsid, and some have an outer lipid envelope derived from the host cell membrane.
4. Step 4: Examine the mechanisms of viral entry into host cells. Animal viruses can enter host cells primarily by two methods: endocytosis, where the virus is engulfed by the cell membrane forming a vesicle, or membrane fusion, where the viral envelope fuses directly with the host cell membrane to release the viral genome inside.
5. Step 5: Based on these points, identify the correct statement. The statement that animal viruses may enter host cells by endocytosis or membrane fusion accurately reflects the known mechanisms of viral entry.