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Harrison's Principles of Internal Medicine, 18e
| Part 8. Infectious Diseases > Section 14 Infections Due to Human Immunodeficiency Virus and Other Human Retroviruses > |
Chapter 188. The Human Retroviruses
Sections: The Human Retroviruses: Introduction, Human T Cell Lymphotropic Virus, Human Immunodeficiency Virus, Further Readings.
Topics Discussed: retroviridae; virology.
Excerpt:"The retroviruses, which make up a large family (Retroviridae), infect mainly vertebrates. These viruses have a unique replication cycle whereby their genetic information is encoded by RNA rather than DNA. Retroviruses contain an RNA-dependent DNA polymerase (a reverse transcriptase) that directs the synthesis of a DNA form of the viral genome after infection of a host cell. The designation retrovirus denotes that information in the form of RNA is transcribed into DNA in the host cell—a sequence that overturned a central dogma of molecular biology: that information passes unidirectionally from DNA to RNA to protein. The observation that RNA was the source of genetic information in the causative agents of certain animal tumors led to a number of paradigm-shifting biologic insights regarding not only the direction of genetic information passage but also the viral etiology of certain cancers and the concept of oncogenes as normal host genes scavenged and altered by a viral vector.All retroviruses are similar in structure, genome organization, and mode of replication. Retroviruses are 70–130 nm in diameter and have a lipid-containing envelope surrounding an icosahedral capsid with a dense inner core. The core contains two identical copies of the single-strand..."
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