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venously with 2000-3000 AU diphtherial antitoxin. Half an hour after
inoculation of the antitoxin, 0.2 ml amounts of the same suspension of
strains is injected intradermally in the opposite half of the animal’s back.
Toxigenic strains produce erythematous reactions around the sites of injection within 48 h. No reaction occurs on the opposite side of the animal’s
back inoculated after intravenous administration of antitoxin (Fig. 43 (l),
( 2 ) ) .
(2)
(1)
FIG. 43. In vivo intradermal toxigenicity test, in rabbit (according to Fraser’s
method). (1) Before the inoculation of diphtherial antitoxin. (a) C. ulceruns Di-tox-;
(b) C. ulceruns Di-tox+; (c) C . ulceruns Di-toxf; (d) C. diphtheriue toxf. ( 2 ) Control
after the inoculation of diphtheriae antitoxin. The intradermal effect of diphtherial toxin in both toxigenic C. diphtheriue and C. ulceruns is neutralised by the
previously inoculated diphtherial antitoxin. (Reproduced from J. gen. Microbiol.
53, 125 (1968).)