Study of the haemolytic process and receptors of thermostable direct haemolysin from Vibrio parahaemolyticus.

The haemolytic action of 125I-labelled thermostable direct haemolysin from Vibrio parahaemolyticus was studied on human and equine erythrocytes. In the first step, the haemolysin bound to the membranes of both erythrocyte species. This binding seemed temperature-independent. Then, for human erythrocytes, haemolysin produced cell disruption, and haemoglobin was released. Following this step, haemolysin was also released in a temperature-dependent manner. In contrast, equine erythrocytes were not disrupted, and no release of haemolysin occurred. The receptors of labelled haemolysin were analysed by assaying the lipid/toxin interaction on a nylon membrane and by binding on thin-layer chromatograms. the ganglioside asialo-GM2 was found to be the most potent receptor, but asialo-GM1 and lactocerebroside may also have been involved.

The novel epidemic strain O139 is closely related to the pandemic strain O1 of Vibrio cholerae.

A new Vibrio cholerae serogroup O139 strain of unknown origin recently emerged in India and Bangladesh, causing a major outbreak of cholera. The genetic relationship between this epidemic strain and the O1 strain responsible for the 7th pandemic of cholera was studied by analyzing the DNA polymorphism of V. cholerae by pulsed-field gel electrophoresis and arbitrarily primed polymerase chain reaction. The restriction patterns of the reference strain O139 Bengal and 10 wild O139 strains isolated early in the Indian outbreak strikingly resemble that of the pandemic O1 strain of V. cholerae El Tor, thus suggesting a close genetic relationship among these strains. This similarity contrasts with the genetic heterogeneity of sporadic non-O1 strains isolated in various parts of the world. Study results strongly suggest that the new epidemic O139 strain is closely related to and might be derived from the pandemic O1 strain of V. cholerae.

[Seroepidemiological survey of El Tor cholera in an endemic region of Algeria]. / Enquête séro-épidémiologique sur le choléra El Tor dans une région endémique en Algérie.

Between the 26th of April and the 8th of july 1987 a seroepidemiological survey was conducted in the district of Chlef located in an endemic cholera area of Algeria. The purpose of this work was to evaluate the seroprevalence of vibriocidal antibodies and to study some epidemiological characteristics of cholera. This survey concerns the representative samples of patients and asymptomatic carriers such as they were declared during the epidemic periods of 1982 and 1986 and a sample of contacts of these latter. A bacteriology of stools practised on all the subjects did not reveal a carrying of vibrios. The seroprevalence was 37.6% and it concerned all ages. It was linked meaningfully to the age category and not to the sex. This seroprevalence was not significantly different between the cases, the carriers and the contacts. Thus this study reveals that Algeria has a seroprevalence rate less important than others countries.

[Value of vibriocidal antibody research in endemic areas of Vibrio cholerae 0:1]. / Intérêt de la recherche des anticorps vibriocides en zones d'endémie à Vibrio cholerae O:1.

We made vibriocidal antibody titration in the serum of some populations in Algeria and in Mali either during or between cholera epidemics. The seropositivity rate was 43.3% in healthy contacts in Alger in 1990 during an epidemic of cholera. For 12/16 healthy contacts examined two times in a 25-day interval, the seropositivity rate increased during the epidemic and the mean of antibody titres rose 8.88 folds. In Constantine, 53% of 195 blood donors had significant titres of vibriocidal antibodies in 1992, 6 years after an epidemic of cholera. The seropositivity rate in population seemed decreasing during this year. In Bamako, 46% of selected patients had significant vibriocidal antibody titres 8 years after the last epidemic of cholera in Mali. Seven of 10 children born after the epidemic had vibriocidal antibodies. These data confirm the persistence of vibriocidal antibodies in population during many years. The importance of the seropositivity rate in healthy contacts and in children born during a non epidemic period shows that asymptomatic infection is frequent and that Vibrio cholerae O:1 may be circulating in population between epidemics. As part of surveillance of cholera outbreaks in endemic areas, it might be of interest to study on a regular basis the vibriocidal antibody seropositivity rate in populations.

[In vitro sensitivity of Vibrio cholerae serotype 0:139 to an intestinal antiseptic tiliquinol-tilbroquinol combination]. / Sensibilité in vitro de Vibrio cholerae du sérotype O:139 à un antiseptique intestinal l'association tiliquinol-tilbroquinol.

O:139 is a new serotype of Vibrio cholerae that is not agglutinated by an O:1 antiserum but causes epidemics of cholera. Strains of O:139 serotype are resistant to O/129 compound and many antibiotics but are sensitive to tetracyclines and tiliquinol-tilbroquinol (Intétrix). The clinical management of the patients infected with serotype O:139 is identical to that of usual choleric patients. However, the immunological difference with O:1 serotype must lead to reconsider both the diagnosis and the vaccinating strategies of cholera.

[Cholera in Benin (epidemic of 1991)]. / Le choléra au Bénin (épidémie de 1991).

Authors report on epidemiologic, bacteriology and therapeutic data related to 1991 cholera outbreak in Benin in the general context of the 7th world pandemic. 7474 cases were notified from all over the country. Vibrio cholerae 01, El Tor biotype, was identified in many patients stools and in the surroundings. Control measures implemented in this situation are described: early parenteral and mainly oral rehydration, antibiotic treatments for patients and contacts, systematic home control around cases, wells disinfection and general hygiene promotion, mobilization of the Civil Service Authorities and population education. Authors conclude that strict epidemiologic monitoring is necessary in epidemic circumstances as well as during endemo-sporadic period.

Influence of low temperature (-30 degrees C) on the different stages of the human allergy mite Dermatophagoides pteronyssinus (Acari: Epidermoptidae).

Effects of low temperature (-30 degrees C) on the different life stages of Dermatophagoides pteronyssinus (Trouessart) were studied. Humid cold air at -30 degrees C killed all stages of mites except eggs after 10 min; after 35 min exposure, 20% of the eggs hatched after the incubation period. Dry, cold air at -30 degrees C killed 40% of all stages of mites except eggs after 4 min and 100% after 5 min; all eggs died after 1 min exposure.

[Simplified vibriocidal antibody titer performed on a drop of blood]. / Titrage simplifié des anticorps vibriocides à partir d'une goutte de sang.

We report a simplified technique for vibriocidal antibody test in underprivileged people in tropical area. The test is performed on a drop of blood sampled on a disc of blotting paper. It avoid taking of large quantities of blood in timid underfed people who are often solicited. Its reading is rapid and easy by the naked eye owing to staining viable germs violet by the neotetrazolium succinate. Tested in mice and humans, the simplified method gave data well correlated to those obtained with the standard test on serum for vibriocidal titres higher than (or equal to) 1/40.

Purification and characterization of Kanagawa haemolysin from Vibrio parahaemolyticus.

The haemolysin of a Kanagawa-phenomenon-positive Vibrio parahaemolyticus strain was purified to apparent homogeneity by acid precipitation, DEAE-Trisacryl, hydroxyapatite and FPLC (Mono-Q) columns: 1.4 micrograms of protein gave a single band on conventional SDS-PAGE with silver staining. The haemolysin was not inactivated by heating for 10 min at 100 degrees C. It was a monomeric protein with a molecular weight estimated to be 29 kDa by PAGE under denaturing and non-denaturing conditions. The haemolysin caused fluid accumulation in the ligated mouse ileum, was cytolytic against cultured mammalian cells and also lysed erythrocytes of various animal species (equine erythrocytes being the most resistant).

[In vivo and in vitro antitumoral effects of an extract from Vibrio cholerae in different murine models. I. Effect in vivo of bacterial extract from Vibrio cholerae on the development of different murine tumoral grafts]. / Effets antitumoraux in vivo et in vitro d'un extrait de Vibrio cholerae dans différents modèles murins. I. Effet in vivo d'un extrait bactérien de Vibrio cholerae sur l'évolution de différentes greffes tumorales murines.

A bacterial extract from Vibrio cholerae, so called DGZ, is shown to prevent transplantation of sarcoma 180 and Lewis lung carcinoma. A 4 days DGZ treatment (4 x 100 micrograms) triggers reject of the graft by 40% of the mice. The mice which have rejected a graft once after treatment, cannot be grafted lately or, at least, the tumor growth is delayed. The association with cisplatinum (4 x 25 micrograms) allows to protect 90 to 95% of the mice.

[In vivo and in vitro antitumoral effects of an extract from Vibrio cholerae in different murine models. II. Antitumoral effect in vitro of an extract from Vibrio cholerae: inhibition of 3LL cell growth and stimulation of murine splenocytes]. / Effets antitumoraux in vivo et in vitro d'un extrait de Vibrio cholerae dans différents modèles murins. II. Effet antitumoral in vitro d'un extrait de Vibrio cholerae: inhibition de la croissance des cellules 3LL et stimulation de splénocytes murins.

A bacterial extract from Vibrio cholerae, the DGZ, has been separated into two fractions by gel filtration. The effects of these two fractions and that of the crude extract are investigated and compared by two different in vitro tests. It appears that these extracts exert direct inhibition over the growth of 3LL cultured cells and that they trigger splenocytes in vitro proliferation.

[Resistance of Vibrio cholerae 0:1 to the 0/129 compound and multiresistance to antibiotics]. / Résistance de Vibrio cholerae O:1 au composé O/129 et multirésistance aux antibiotiques.

The authors present a study of the in vitro susceptibility to O/129 compound and usual antibiotics of 29 strains of V. cholerae O:1 biotype El Tor isolated during epidemics in miscellaneous countries over the world from 1982 to 1991. Several identical isolates from the same epidemic are represented by one strain. Susceptibility testing by diffusion method and MICs by agar dilution method are used. The data show that the resistance to O/129 compound is often associated with the resistance to usual antibiotics such as trimethoprim, sulphonamides, chloramphenicol, ampicillin and tetracycline. This resistance to the vibrostatic compound leads to a double problem of diagnosis and therapy. The nitrofuranes derivatives and tiliquinol-tilbroquinol association, an intestinal antiseptic, are the most active antimicrobial agents as well on the strains O/129 sensitive as on the strains O/129 resistant.