Skip directly to search Skip directly to A to Z list Skip directly to site content
CDC Home

Volume 3, Number 4—December 1997

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 3

Genetic evolution

Microbes (bacteria, viruses, fungi, protozoa)
Rapid and incessant
Huge population sizes 1014+ and generation times in minutes vs. years
Intraclonal process
DNA replicationmay be error-pronein sea of mutagens sunlight; unshielded chemicals, incl. natural products
RNA replicationintrinsically unedited, >10-3 swarm species
Haploid: immediate manifestation, but partial recessives not accumulated contra multicopy plasmids
Site-directed inversions and transpositions:
phase variation
?? Other specifically evolved mechanisms:
genome quadrant duplication; silencing
Interclonal process
Promiscuous recombinationnot all mechanisms are known
Conjugationdozens of species
Viral transduction and lysogenic integration:
Classical: phage-borne toxins in C. diphtheriae
Plasmid interchange (by any of above) and integration
Toxins of B. anthracis
Pasteur: heat attenuation: plasmid loss; chemically induced
RNA viral reassortment; ?? and recombination?
Transgressive—across all boundaries
Artificial gene splicing
Bacteria and viruses have picked up host genes (antigenic masking?)
Interkingdom: P. tumefaciens and plants, E. coli and yeast
Vegetable and mineral! oligonucleotides and yeast.
Host-parasite coevolution
Coadaptation to mutualism or accentuation of virulence?
Jury is still out (May and Anderson). Many zoonotic convergences.
Probably divergent phenomena, with short-term flareups and Pyrrhic
victories, atop long-term trend to coadaptation.

Main Article

Top of Page The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30333, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO