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Generation and release into the culture medium of a cytolytic toxin by Gardnerella vaginalis has been demonstrated. Addition of starch and of the nonionic detergent Tween 80 to the culture medium was essential to recover cytolytic activity. A protein with an apparent molecular mass of 61 to 63 kDa was purified from the culture supernatants showing lytic activity towards erythrocytes and nucleated cells, such as human endothelial cells and human neutrophils. The protein had marked selectivity for human erythrocytes, while erythrocytes from other species were not lysed or were lysed at much higher concentrations of the protein than those needed for human erythrocytes. The cytolytic activity was remarkably unstable in polar media, but was stabilized by nonionic detergents, by binding, or by insertion into the target cell membrane, suggesting its amphiphilic nature.

Forty-five subjects with a complete deficiency of myeloperoxidase were identified in an area of the region Friuli-Venezia Giulia in north-eastern Italy using the Hemalog D system as the screening technique. Histochemical and biochemical tests performed on the leucocytes of some of these subjects confirmed the defects shown by the Hemalog D system. The defect was of genetic origin in seven subjects. The genetic origin could be suspected in another eight subjects since more than two affected members were present in a given family. Eosinophil peroxidase, which is present in MPO deficient subjects, interfered with the guaiacol assay of MPO, and in several cases masked the genetic transmission. An assay was developed using o-dianisidine as the electron donor which considerably reduced the interference by EPO. With this assay an autosomal recessive pattern of inheritance was found. The MPO deficient leucocytes had a higher respiratory burst than control cells and an impaired bactericidal activity, at early post-phagocytic periods, which became comparable to that of control cells at later stages. Particle ingestion by the MPO-deficient cells was normal.

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The transmissible nature of the genetic factor in Escherichia coli, which controls a-haemolysin production, was recognized by Smith & Halls (1967). The element responsible was termed Hly. The f i f character of Hly factor was described at the same time. Goebel & Schrempf (1971) demonstrated the presence in the cytoplasm of a haemolytic E. coli strain of a covalently-closed circular DNA molecule with a contour length of 29.5 ? 0.5 pm, which was transferred to non-haemolytic strains together with the haemolytic character. Therefore this DNA species represents the Hly factor. However, Hly factor was not taken into account by Hedges & Datta (1972), who classified the F-like plasmids into four compatibility groups. A further group of F-like plasmids was subsequently added by Naomi Datta in 1974 (personal communication), Folac being the prototype of it (Falkow & Baron, 1962). In the present paper we show that Hly factor determines the production of F-type pili and that it is compatible with F-like plasmids of all the five groups previously described. Escherichiu coli strain ~2 1 2 carrying Hly factor was received from H. Williams Smith. Escherichia coli strains ~5 3 and c600, carrying many known plasmids, were provided by Naomi Datta. R7, R89 and R120, three F-like R factors recently identified in Triest, were also used. Crosses were carried out by mixing equal numbers (about 2 x 107/ml) of donor and recipient cells in nutrient broth, which was subsequently incubated overnight at 37 "C. Colonies were then counted on nutrient or blood agar containing, if required, appropriated amounts of different antibiotics to define the number of donor, recipient and recombinant cells. Colonies producing colicin were identified by standard techniques. To test for the compatibility of plasmids, recombinant clones were purified on nonselective medium and tested by replica plating for the presence of each plasmid. The fif character of Hly factor was confirmed in our study. Moreover, we could show that E. coli strains carrying the Hly factor allowed a small but definite increase in the titre of MS2 phage (Davis, Strauss & Sinsheimer, 1961). This demonstrates that Hly controls the synthesis of F-pili. Being not perfectly clear from the data reported by Smith & Linggood (1970) and Smith & Heller (1973) whether Hly is self-transmissible or mobilized by the F factor, we tested different strains of E. coli K I 2 F-, which had acquired the Hly factor from E. coli strain ~2 1 2 , for sensitivity to the female-specific phages T7 and $2 (Makela, Makela & Soikkeli, 1964; Cuzin, 1965). The Hly-positive bacteria remained sensitive to these phages. Hly factor was transmissible from these bacteria by conjugation. It appears, therefore, that at least the Hly factor used in the present study, for which we propose the name of Hly-Pzrz, is selftransmissible.

Phagocytosis of Borrelia burgdorferi by human polymorphonuclear leukocytes triggers oxygen-dependent and -independent mechanisms of potentially cidal outcome. Nevertheless, no factor or process has yet been singled out as being borreliacidal. We have studied the B. burgdorferi-killing ability of the myeloperoxidase-H2O2-chloride system and that of primary and secondary granule components in an in vitro assay. We found that neither secondary granule acid extracts nor the chlorinating system could kill these microorganisms, while primary granule extracts were effective. The Borrelia-killing factor was purified to homogeneity and demonstrated to be elastase. Its cidal activity was found to be independent of its proteolytic activity.

A eytotytis toxin gr~duecd by C, vrr#innli.r WBX incorporated in ~rrislsirl membrnnrs and giant lipotemca. The taxin t'otmed ionic &arm& when incr)rpQrrrrd in lipid bilryera. 7% elce~ricrl properties er such channels were rludicd. Currcnr rccordn rcw~ltd 11 unitary eondurlunec of I 26 pS (in x~mmctricsl ISO mM KCI), The @en ntuls prebirbility of the cy~al&n formed rhennclw wax n Bune~lan of the Lpplicd membrane patcnrial.The permeability ratia alMans to ~nionx wxx estimated IQ bc 6.5, I INTROBUCTIONGarcim=@lla Ya&inah is an apporruniatie QathOgen, which is closely associated with bacterial vaginitis [1,2]$ A cytolytic toxin (CTOX) produced by G. vnginalis has been rcccnrIy described [3], This toxin is an amphiphilic protein with a molecular mass of 61-43 kDa [3], The CTOX has r? lyric activity towards human crythrocytes and nucleated cells, such as human endothelial cells and