76
A. SARAGEA ET AL.
toxigenic (tox-) strains of C. dzphtheriae could be obtained, differing from
one another by only one prophage and by their toxigenic capacity, it became
obvious that “invasiveness” (virulence) atld toxigenicity were separable
properties (Barksdale et al., 1960; Van Heyningen and Arseculeratne,
1964; Murata et al., 1959).
For example, rabbits infected with the original strain (tox-), developed
pseudomembranous lesions, but later recovered, whereas rabbits infected
with the toxigenic pair strain ( t o x f ) developed necrotic lesions and died.
This separation of invasiveness from toxigenicity was consistent with the
reported cases of mild diphtheritic infections in man caused by nontoxigenic diphtheria bacilli, as well as with those records of atypical
clinical cases of diphtheria occurring in individuals who possess circulating
antitoxin (Belsey et al., 1969; Barksdale, 1970; Brooks et al., 1974).
Easily distinguishable properties, “invasiveness” and “toxigencity”,
are also evident in the wide spread (in Romania) during the present postepidemic period, in very well immunised children, of a large number of
non-toxigenic strains in healthy carriers. Sometirnes cause, e.g. sore throat,
chills or erythematous angina from which patients usually recover without any treatment.
Virulence (invasiveness) is obviously under the genetic control of the bacterium, while toxigeny is under that of the temperate corynebacteriophage.
Thus, “invasiveness” is expressed by the growth of bacilli at the site of
infection (pseudomembrane) and is related to certain protein and lipid
components associated with their surfaces (Huang, 1942a, b ; Lautrop,
1950, 1955; Kato, 1970) while toxinogeny is related to and dependent on
the presence of prophage in the bacterial genome.
111. DIPHTHERIAL TOXIN
A. Phage-bacteria relationships in C. diphtheriae
1. Lysogeny and toxin production
(a) General considerations. Lysogeny is the perpetuation of temperate
bacteriophages, prophages, as a part of the bacterial replicating system
(Barksdale and Arden, 1974).
When a non-lysogenic bacterium like C. dz$htheriae incorporates the
genome of a temperate bacteriophage into its chromosome it becomes
lysogenic-it has been lysogenised; it carries a phage genome as a prophage.
I n the change from the non-lysogenic to the lysogenic state, bacteria
acquire the capacity to release phage either after ultraviolet light induction,
by chemical induction or by other physical conditions as, for instance,
shaking cultures, thus acquiring a state of immunity against the liberated
phage.
A. SARAGEA ET AL.
toxigenic (tox-) strains of C. dzphtheriae could be obtained, differing from
one another by only one prophage and by their toxigenic capacity, it became
obvious that “invasiveness” (virulence) atld toxigenicity were separable
properties (Barksdale et al., 1960; Van Heyningen and Arseculeratne,
1964; Murata et al., 1959).
For example, rabbits infected with the original strain (tox-), developed
pseudomembranous lesions, but later recovered, whereas rabbits infected
with the toxigenic pair strain ( t o x f ) developed necrotic lesions and died.
This separation of invasiveness from toxigenicity was consistent with the
reported cases of mild diphtheritic infections in man caused by nontoxigenic diphtheria bacilli, as well as with those records of atypical
clinical cases of diphtheria occurring in individuals who possess circulating
antitoxin (Belsey et al., 1969; Barksdale, 1970; Brooks et al., 1974).
Easily distinguishable properties, “invasiveness” and “toxigencity”,
are also evident in the wide spread (in Romania) during the present postepidemic period, in very well immunised children, of a large number of
non-toxigenic strains in healthy carriers. Sometirnes cause, e.g. sore throat,
chills or erythematous angina from which patients usually recover without any treatment.
Virulence (invasiveness) is obviously under the genetic control of the bacterium, while toxigeny is under that of the temperate corynebacteriophage.
Thus, “invasiveness” is expressed by the growth of bacilli at the site of
infection (pseudomembrane) and is related to certain protein and lipid
components associated with their surfaces (Huang, 1942a, b ; Lautrop,
1950, 1955; Kato, 1970) while toxinogeny is related to and dependent on
the presence of prophage in the bacterial genome.
111. DIPHTHERIAL TOXIN
A. Phage-bacteria relationships in C. diphtheriae
1. Lysogeny and toxin production
(a) General considerations. Lysogeny is the perpetuation of temperate
bacteriophages, prophages, as a part of the bacterial replicating system
(Barksdale and Arden, 1974).
When a non-lysogenic bacterium like C. dz$htheriae incorporates the
genome of a temperate bacteriophage into its chromosome it becomes
lysogenic-it has been lysogenised; it carries a phage genome as a prophage.
I n the change from the non-lysogenic to the lysogenic state, bacteria
acquire the capacity to release phage either after ultraviolet light induction,
by chemical induction or by other physical conditions as, for instance,
shaking cultures, thus acquiring a state of immunity against the liberated
phage.