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A mutant MT of Micrococcus lysodeikticus (luteus) IFO 3333, whose minimum growing unit is not a single cell, but a tetrad unlike the wild‐type divides by binary fission of each monococcus, and then separates first into two daughter tetrads, second into four tetrads and third into eight tetrads. The three planes of either the cell division or the cell separation are equivalent to one another and oriented at right angles in three dimensions, respectively. The process of consecutive cell divisions and separations of the mutant tetrads was schematically illustrated.

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ABSTRACT. The protective effects of Clostridium sordellii lethal toxin (LT) and hemorrhagic toxin (HT) toxoids against challenge with spores in guinea pigs were investigated. Purified LT and partially purified HT were obtained from the culture supernatant of C. sordellii strain 3703, and then were treated with formalin to make toxoids. LT, HT and combined LT and HT (LT / HT) toxoid vaccines were prepared by mixing each toxoid with an aluminum phosphate gel as adjuvant. Guinea pigs immunized twice with the respective toxoid vaccines were challenged with spores of strains 3703 or KZ1047. The latter strain does not produce HT. LT toxoid vaccine conferred protection against challenge with strain KZ1047, but not strain 3703, in guinea pigs. All guinea pigs immunized with HT toxoid vaccine died after challenge with spores of either strain. LT/HT toxoid vaccine gave complete protection against challenge with spores of strains 3703 and KZ1047 to guinea pigs. These results suggest that not only LT toxoid, but also HT toxoid, are essential protective antigens of C. sordellii. KEY WORDS: Clostridium sordellii, HT, LT, toxoid.J. Vet. Med. Sci. 63(8): 879-883, 2001 Clostridium sordellii causes gas gangrene in humans [19] and animals [7,18], and it has also been known as an agent of enteritis in cattle and sheep [2][3][4]7]. The diseases associated with C. sordellii have been controlled by toxoids and bacterins in animals [7]. The pathogenic C. sordellii strains produce lethal toxin (LT) alone or both LT and hemorrhagic toxin (HT) [15,24]. LT has edematizing and cytotoxic activities in addition to its lethal toxicity [5,17]. HT has much weaker lethal and cytotoxic activities than LT [5,12,17]. Consequently, LT masks the action of HT in culture supernatants, and the differentiation between pathogenic and nonpathogenic C. sordellii strains has been conventionally based on LT production [8]. A consequence of this is that C. sordellii vaccines have been produced on the basis of inducing LT-specific antitoxins alone, however, the lethal activity of HT is not as low as the activities of other clostridial lethal toxins [6,20,21].The toxins of C. sordellii have often been compared with toxin A and toxin B produced by C. difficile [5,12,15,17]. The biological and antigenic properties of toxin A and toxin B are very similar to those of HT and LT [5,12,17,23,24]. Both toxoid A and toxoid B are essential for complete protection in hamsters with a C. difficile vaccine [10].The necessity of HT toxoid for protection against bacterial infections has not fully been investigated. In this study, we examined the protective effects of toxoids against lethal challenge with C. sordellii spores in guinea pigs. MATERIALS AND METHODSBacterial strains: C. sordellii strain 3703 (LT-positive, HT-positive) [14-16, 23, 24] and strain KZ1047 (LT-positive, HT-negative) [14,16,23] were obtained from the Department of Bacteriology at the School of Medicine of Kanazawa University, Kanazawa, Japan.Preparations of purified LT and partially purified HT toxoids...

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