TABLE 2-4 Representative Examples of Virulence Factors Encoded by Bacteriophages, Plasmids, and Transposons

Mobile Genetic Element


Virulence Factor


Streptococcus pyogenes

Escherichia coli

Staphylococcus aureus

Erythrogenic toxin

Shiga-like toxin

Enterotoxins A D E


TSST-1 toxin


Clostridium botulinum

Neurotoxins C D E


Corynebacterium diphtheriae

Diphtheria toxin


Escherichia coli

Enterotoxins LT, ST

Pili colonization factor



Serum resistance factor

Adherence factors

Cell invasion factors


Bacillus anthracis

Edema factor

Lethal factor

Protective antigen

Poly-D-glutamic acid capsule


Yersinia species

Intracellular growth factor

Capsule production factor


Yersinia pestis



Murine toxin


Escherichia coli

Heat-stable enterotoxins

Aerobactin siderophores?

Hemolysin and x-pili operons?


Shigella dysenteriae

Shiga toxin?


Vibrio cholerae

Cholera toxin

ZOT toxin

ACE toxin

NOTE: TSST-1=toxic shock syndrome toxin-1; LT=heat-labile enterotoxin; ST=heat-stable enterotoxin; ZOT=zona occuldens toxin; ACE=accessory cholera enterotoxin; ?=the DNA structure strongly suggests a transposon, but actual transposition has not been demonstrated.

SOURCE: J. Mekalanos, Department of Microbiology and Molecular Genetics, Harvard Medical School.

meningitis. Microscopic examination and culture of cerebrospinal fluid (CSF), however, were negative for Neisseria meningitidis (Centers for Disease Control, 1985). Within the next two years, additional outbreaks and isolated cases were reported in nine other towns in São Paulo State. It was also determined that a similar outbreak had occurred in May 1984, in the neighboring state of Paraná (Centers for Disease Control, 1985, 1986; Brazilian

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