![](/olcweb/styles/shared/spacer.gif) | ![](/sites/dl/free/0072320427/title/cover_image.JPG) Foundations in Microbiology, 4/e Kathleen Park Talaro,
Pasadena City College Arthur Talaro
Introduction to Viral Diseases and DNA Viruses
Chapter Overview- Among microbial groups, viruses cause the majority of infections.
- Viruses are extremely small parasites composed of a nucleic acid core surrounded by a protein capsid.
- Viruses invade host cells by using specific receptors, and they induce the cell machinery to synthesize, assemble, and release new viruses.
- Virus infections vary from mild to severe in effect, local to systemic in scope, and may have the potential for latency and oncogenicity.
- DNA viruses of humans exist in the enveloped or naked state and can carry double-stranded or single-stranded DNA.
- Poxviruses are large, complex DNA viruses that cause smallpox and molluscum contagiosum.
- Herpesviruses are enveloped DNA viruses that are known for being latent in host cells after the initial infection.
- Examples of common herpesvirus diseases are cold sores, genital herpes, chickenpox, shingles, mononucleosis, and roseola.
- Herpesviruses also cause cancers such as lymphoma and sarcoma.
- One cause of hepatitis is hepatitis B virus, an enveloped virus that damages the liver and may cause cancer.
- Nonenveloped DNA viruses are the adenoviruses, one cause of colds, and papillomaviruses, the agents of common skin and genital warts.
- Parvoviruses are single-stranded DNA viruses and are implicated in a respiratory infection of children.
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