Animal Virus Life Cycles: An Overview

V. VIRUSES

F. ANIMAL VIRUS LIFE CYCLES: AN OVERVIEW

Viruses are infectious agents with both living and nonliving characteristics.

1. Living characteristics of viruses

a. They reproduce at a fantastic rate, but only in living host cells.

b. They can mutate.

2. Non-living characteristics of viruses

a. They are acellular, that is, they contain no cytoplasm or cellular organelles.

b. They carry out no metabolism on their own and must replicate using the host cell's metabolic machinery. In other words, viruses don't grow and divide. Instead, new viral components are synthesized and assembled within the infected host cell.

c. The vast majority of viruses possess DNA or RNA but not both.

F. Life Cycle of Animal Viruses

Viruses that infect animal cells replicate by means of what is called the productive life cycle. Some viruses, such as HIV and the herpes viruses are able to become latent in certain cell types. A few viruses increase the risk of certain cancers.

We will now look at the life cycles of viruses that infect animal cells.

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