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Volume 3, Number 4—December 1997
THEME ISSUE
Foodborne
Special Issue

Infectious Disease as an Evolutionary Paradigm

Joshua Lederberg
Author affiliation: Sackler Foundation Scholar, Rockefeller University, New York, New York, USA

Main Article

Table 2

The origin of viruses

Viruses are genomic fragments that can replicate only in the context of an intact living cell. They cannot therefore be primitive antecedents of cells.
Within a given species, viruses may have emerged as genetic fragments or reduced versions from chromosomes, plasmids, or RNA of
1) the host or related species
2) distant species
3) larger parasites of the same or different hosts
4) further evolution and genetic interchange among existing viruses
Once established, they may then cycle back into the genome of the host as an integrated episome; there they may have genetic functions or in principle might reemerge as new viruses.
These cycles have some substantiation in the world of bacterial viruses; but we have no clear data on the provenience of plant or animal viruses.

Main Article

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The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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