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N Guiso

Publications and source records attributed to N Guiso.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Epidemiological estimation of the effectiveness of the pertussis vaccination during outbreaks in a community. Les pédiatres et bactériologistes du réseau RENACOQ].

BACKGROUND: With the recent pertussis vaccine trials, the efficacy of acellular vaccines is now well known, estimated at 85% for multicomponent vaccines. On the other hand, the estimates of whole cell vaccines efficacy varies from 36% to 98% with the different vaccines used. We evaluated the field effectiveness of the French whole cell pertussis vaccine during outbreaks in schools and centers for disabled children. METHODS: Four limited outbreaks between 1993 and 1995 were investigated using a retrospective cohort study design. Vaccine effectiveness (VE) was assessed for the following case definition: clinical pertussis, laboratory-confirmed pertussis, epidemiologically confirmed pertussis (documented contact with a laboratory confirmed case). Immunization history was obtained by reviewing the child health record book. Effectiveness of a whole vaccination (four injections) and of a partial vaccination (one to three injections) were estimated as 1-(attack rate among vaccinated/attack rate among non-vaccinated). RESULTS: A whole immunization conferred good protection against pertussis with an estimated VE higher than 92% in three surveys, lower in the fourth survey (84%) in which antibiotic prophylaxis was set up very rapidly. A partial immunization conferred a mild protection (median: 60%). CONCLUSIONS: These results are consistent with a previous report about the effectiveness of this whole cell vaccine using the screening method in a hospital network survey in France. In the same way, a large efficacy trial in Senegal comparing it with an acellular bivalent vaccine estimated its efficacy at 96%. This high efficacy together with a satisfactory vaccine coverage leads to the current epidemiological profile of pertussis in childhood in France: majority of cases occurring before 6 months of age, limited outbreaks in school children, many of whom being unvaccinated or partially vaccinated.

Adolescent↗
PubMed1997

Rapid diagnosis of pertussis in young infants: comparison of culture, PCR, and infant's and mother's serology.

The contribution of maternal pertussis serology comparing prepartum serum to serum collected during the infant's disease to the diagnosis of pertussis in infants was evaluated for 28 pairs of young infants with pertussis syndrome and their mothers and was compared to those of culture and PCR. Infants had a nasopharyngeal aspiration tested by PCR, and acute and convalescent sera were collected during their disease. Mothers had a first acute serum collected concomitantly with the infant's acute serum, and both acute sera were compared to a prepartum serum. Sera were analyzed by immunoblotting for the detection of anti-pertussis toxin (PT) antibodies. Serological evidence of pertussis in infants was assessed as either an increase in anti-PT antibody levels between the mother's prepartum and acute sera or the presence of antibodies in the infant's acute serum and their absence in both the mother's acute and prepartum sera. Culture and PCR sensitivity were 43 and 89%, respectively. Most infants (18 of 24) had no pertussis antibody detectable in their acute sera, confirming a delayed immune response at this age. A comparison of infant's and mother's serology, using prepartum serum, rapidly confirmed the diagnosis in 57% of the cases. Although less sensitive than PCR, this serological method should be used for a rapid diagnosis of pertussis in young infants when culture and PCR are either not available or negative.

Adult↗
PubMed1997

Cloning and characterization of an Mn-containing superoxide dismutase (SodA) of Bordetella pertussis.

The Fur titration assay (FURTA) recently developed by I. Stojiljkovic and coworkers (J. Mol. Biol. 236:531-545, 1994) was applied to clone iron-regulated genes of Bordetella pertussis. After sequence analysis, one of the clones obtained by this selection procedure was shown to contain an open reading frame with significant sequence similarities to Mn-containing superoxide dismutases (SodA). The open reading frame was preceded by a Fur consensus binding site, which according to primer extension analysis overlaps the -10 region of the sodA promoter. Southern blot analysis also revealed the presence of sodA homologous sequences in Bordetella bronchiseptica. On the transcriptional level, sodA expression is strictly iron regulated in both organisms and also in the heterologous host Escherichia coli harboring a plasmid with the sodA gene. Accordingly, SodA-mediated superoxide dismutase activity in Bordetella lysates was detected only after cultivation of the bacteria in iron-restricted media. A B. bronchiseptica fur mutant constitutively expressed SodA, thereby confirming the functional similarity of the iron regulatory systems in the two genera. Apart from iron regulation, sodA expression was affected by changes in DNA topology induced by coumermycin A but not by the global virulence regulatory Bvg system. B. pertussis and B. bronchiseptica sodA deletion mutants did not show significant changes in their growth properties. In contrast, mutation of the previously described Fe-containing SodB enzyme resulted in clones strongly impaired in viability. No direct involvement of SodA in bacterial virulence could be revealed because deletion of the sodA gene affected survival of Bordetella species neither in cultured macrophages nor in a mouse respiratory infection model.

Amino Acid Sequence↗
PubMed1997

Isolation, identification and characterization of Bordetella pertussis.

During the pertussis clinical trials, the best conditions for isolating B. pertussis were determined. Isolation is higher if two nasopharyngeal aspirates are collected, transport is carried out at ambient temperature and takes no longer than 48 hours, Reagan Lowe or Bordet Gengou selective and non-selective plates are used and incubated at 36 degrees C for seven days. Identification must include Gram stain and urease, oxidase and nitrate reactions. Confirmation is obtained with specific anti-B. pertussis antiserum. Characterization of the isolates can be performed by using the polymerase chain reaction, serotyping and pulsed-field gel electrophoresis.

Adult↗
PubMed1996

In vivo and in vitro analysis of Bordetella pertussis catalase and Fe-superoxide dismutase mutants.

Bordetella pertussis produces a catalase and a Fe-superoxide dismutase. The importance of these enzymes in virulence was investigated, in vitro as well as in vivo, by using mutants deficient in their production. The catalase-deficient mutant survived within polymorphonuclear leukocytes, killed J774A.1 macrophages through apoptosis, and behaved as the parental strain in a murine respiratory infection model. These results suggest no direct role for catalase in B. pertussis virulence. The absence of expression of Fe-superoxide dismutase had profound effects on the bacterium including a reduced ability to express adenylate cyclase-hemolysin and pertactin, two factors important for B. pertussis pathogenesis. The Fe-superoxide dismutase-deficient mutant also had decreased abilities to colonize and persist in the murine respiratory infection model.

Adenylate Cyclase Toxin↗
PubMed1996

Intranasal inoculation of Bordetella bronchiseptica in mice induces long-lasting antibody and T-cell mediated immune responses.

Humoral and cellular immune responses were analysed in mice inoculated intranasally with Bordetella bronchiseptica. After infection, the number of bacteria that colonized the respiratory tract of the mice increased during the first day and decreased thereafter. Total IgG levels increased as early as 14 days after infection and decreased with time after infection, whereas total IgA and IgM levels were lower but remained stable. Specific antibodies to the bacteria were mainly IgG2a and IgA and persisted up to 10 months after infection. Some of these specific antibodies were directed against adenylate cyclase-haemolysin, the bacterial factor that had been shown to be necessary for initiation of infection. The proliferation of Bordetella bronchiseptica-reactive spleen cells occurred during the acute phase of infection. T cells from infected mice produced increasing amounts of IFN gamma and IL-2 after infection. Although very low levels of IL-10 were produced, no IL-4 was detected after bacterial stimulation in vitro. These results suggest that Bordetella bronchiseptica infection induces primarily a Th1-type T-cell response. Importantly, the authors demonstrated that antibody and T-cell responses directed against bacterial determinants of the virulent strain and to purified adenylate cyclase-haemolysin were long-lasting. This observation could be due to the fact that Bordetella bronchiseptica may persist intracellularly in the host as it was demonstrated in vitro.

Adenylate Cyclase Toxin↗
PubMed1996

Long-term human serum antibody responses after immunization with whole-cell pertussis vaccine in France.

Three hundred sixty children were tested for pertussis serology 0.5 to 1.58 months after complete whole-cell pertussis vaccination. An immunoblot assay was used to detect serum antibodies to pertussis toxin, filamentous hemagglutinin, adenylate cyclase-hemolysin, and pertactin, and agglutination was used for detection of anti-agglutinogen antibodies. Antibodies against pertussis toxin, pertactin, and agglutinogens decreased rapidly after vaccination but increased secondarily, suggesting exposure to infected persons. In contrast, anti-filamentous hemagglutinin antibodies persisted and anti-adenylate cyclase-hemolysin antibodies increased continuously, suggesting either cross-reaction with non-Bordetella antigens or exposure to Bordetella isolates expressing these two antigens, including Bordetella pertussis. These data suggest that unrecognized pertussis is common in France despite massive and sustained immunization in infants and that vaccinated children become susceptible to infection more than 6 years after their last vaccination.

Adenylate Cyclase Toxin↗
PubMed1995

Induction of macrophage apoptosis by Bordetella pertussis adenylate cyclase-hemolysin.

We previously demonstrated that Bordetella pertussis induced macrophage apoptosis and that adenylate cyclase-hemolysin expression is required for this phenomenon. In order to determine a role for other B. pertussis factors, such as pertussis toxin or the adhesins, pertactin and filamentous hemagglutinin, we compared mutants deficient in adhesin expression or purified proteins for their ability to induce cell death. We showed that only purified adenylate cyclase-hemolysin, but neither adhesins, nor pertussis toxin, killed macrophages through apoptosis. We also demonstrated that all activities of adenylate cyclase-hemolysin were required. Moreover, our results indicate that B. pertussis does not have to invade cells to be lethal.

Adenylate Cyclase Toxin↗
PubMed1995

Cloning and sequence of the Bordetella bronchiseptica adenylate cyclase-hemolysin-encoding gene: comparison with the Bordetella pertussis gene.

The cyaA gene from Bordetella bronchiseptica (Bb), encoding the adenylate cyclase-hemolysin (AC-Hly), has been cloned and its complete nucleotide sequence has been determined. The deduced amino-acid sequence was compared to the AC-Hly from B. pertussis (Bp) and the main differences were found in the C-terminal repeat region of the molecule.

Adenylate Cyclase Toxin↗
PubMed1995

The C-terminal domain is essential for protective activity of the Bordetella pertussis adenylate cyclase-hemolysin.

The adenylate cyclase-hemolysin of Bordetella pertussis consists of a cell-invasive N-terminal adenylate cyclase domain linked to a C-terminal RTX hemolysin containing extensive glycine-rich repeats. The toxin is an essential virulence factor required in the initial stages of infection. Adenylate cyclase-hemolysin was also shown to be a potent vaccinating antigen inducing protection against B. pertussis colonization of the mouse respiratory tract. This protective activity depends on a posttranslational fatty-acylation modification. We used a set of deletion derivatives of the recombinant adenylate cyclase-hemolysin to localize the protective epitopes on the 1,706-residue toxin. We show that specific anti-adenylate cyclase-hemolysin antibodies present in the sera of B. pertussis-infected mice and humans are directed predominantly against the modification-and-repeat portion of the toxin, contained in the last 800 residues of the adenylate cyclase-hemolysin. These antibodies appear to recognize conformational epitopes present only in a structure formed by the intact C-terminal half of the toxin. There was no correlation between the capacity of the truncated adenylate cyclase-hemolysin derivatives to induce both toxin-neutralizing antibodies upon immunization of mice and protective immunity. However, only the truncated proteins which were recognized by the sera of infected mice and humans and which had their last 800 residues intact had the capacity to induce protection of mice against colonization by B. pertussis. This indicates that the structure of the modification-and-repeat region of adenylate cyclase-hemolysin is critical for its protective activity.

Adenylyl Cyclases↗
PubMed1995

Human Bordetella bronchiseptica infection related to contact with infected animals: persistence of bacteria in host.

Within a period of 2 1/2 years, Bordetella bronchiseptica was isolated four times from a 79-year-old woman with bronchopneumonia. We have demonstrated by pulsed-field gel electrophoresis that this infection was related to contact with infected rabbits. The initial human B. bronchiseptica isolate had a phenotype characteristic of usual B. bronchiseptica clinical isolates; it produced toxin and adhesins, such as adenylate cyclase-hemolysin, filamentous hemagglutinin, and pertactin, and was able to induce lethality in a murine respiratory model. By contrast, although the three successive human isolates produced adhesins, they did not express adenylate cyclase-hemolysin and were unable to induce lethality. This implies that adenylate cyclase-hemolysin is required to induce lethality. We suggest that B. bronchiseptica may persist in the host, with expression of adenylate cyclase-hemolysin being essential for the initiation of infection and expression of adhesins being essential for persistence.

Adenylyl Cyclases↗
PubMed1994

Characterization of murine lung inflammation after infection with parental Bordetella pertussis and mutants deficient in adhesins or toxins.

Bordetella pertussis expresses factors such as filamentous hemagglutinin, agglutinogens, pertactin, and pertussis toxin, which participate in bacterial adhesion; pertussis toxin, dermonecrotic toxin, lipopolysaccharide, and tracheal cytotoxin, which are responsible for toxic effects; and adenylate cyclase-hemolysin, which is required to initiate infection. By using a murine respiratory model, we showed that the RGD sequences of filamentous hemagglutinin and pertactin are important for bacterial persistence. However, mutants deficient in filamentous hemagglutinin and agglutinogens or in pertactin and the RGD sequence of filamentous hemagglutinin behaved as did wild-type B. pertussis, i.e., induced bronchopneumonia, alveolitis, and an influx of macrophages, lymphocytes, and polymorphonuclear leukocytes into bronchoalveolar lavage fluids. These results suggest that these adhesins are not involved in the induction of pulmonary lesions following infection. The intensity of inflammation was markedly reduced after infection with mutants deficient in either hemolytic activity or pertussis toxin expression, whereas a mutant devoid of adenylate cyclase activity behaved as did the avirulent mutant. Pertussis toxin and adenylate cyclase-hemolysin may act indirectly by altering immune cell functions and thus allowing other factors, such as filamentous hemagglutinin, agglutinogens, and pertactin, to trigger adhesion and lipopolysaccharide, dermonecrotic toxin, and tracheal cytotoxin to induce their toxic effects. However, it is possible that pertussis toxin is also responsible for the induction of some pulmonary alterations.

Amino Acid Sequence↗
PubMed1993

Western blot analysis of antibody responses of young infants to pertussis infection.

Western blot and agglutination techniques were used to analyze the antibody responses to Bordetella pertussis in 27 infants less than six month of age with presumed pertussis infection. The antibody response to the Bordetella pertussis adhesions filamentous hemagglutinin, pertactin and agglutinogens, and to the Bordetella pertussis toxins pertussis toxin and adenylate cyclase-hemolysin were compared. Infection induced intense antibody responses to filamentous hemagglutinin, pertussis toxin and adenylate cyclase-hemolysin. Antibodies to agglutinogens were never detected, and antibodies to pertactin were rarely detected in infected infants' sera. Therefore, determination of anti-agglutinogens levels only is not suitable for the serological diagnosis of pertussis in young infants. Use of purified filamentous hemagglutinin, pertussis toxin and adenylate cyclase-hemolysin in Western blot analysis may improve the serodiagnosis of Bordetella infections. However, care must be exercised in distinguishing between the antibody response in young infants and maternally derived antibodies.

Adenylate Cyclase Toxin↗
PubMed1993

Bordetella pertussis induces apoptosis in macrophages: role of adenylate cyclase-hemolysin.

Bordetella pertussis, the causative agent of whooping cough, has been shown recently to enter and survive in epithelial cells and macrophages in vitro. In the present study, we show that B. pertussis is cytotoxic for J774A.1 cells, a monocyte-macrophage cell line, and for murine alveolar macrophages. We demonstrate that cell cytotoxicity mediated by B. pertussis occurred through apoptosis, as shown by changes in nuclear morphology and by host cell DNA fragmentation. Parental strains and a mutant deficient in pertussis toxin expression are able to induce apoptosis, whereas avirulent mutant or adenylate cyclase-hemolysin-deficient mutants are not cytotoxic. Both adenylate cyclase and hemolytic activities are required for programmed cell death. These results show that induction of apoptosis is dependent on the expression of adenylate cyclase-hemolysin. The infection of murine alveolar macrophages in primary culture with B. pertussis leads to apoptosis, suggesting that this process might be relevant in vivo. The ability of B. pertussis to promote cell death may be important for the initiation of infection, bacterial survival, and escape of the host immune response.

Adenylyl Cyclases↗
PubMed1993

Virulence of Bordetella bronchiseptica: role of adenylate cyclase-hemolysin.

Bordetella bronchiseptica is a pathogen of laboratory, domestic, and wild animals and sometimes of humans. In the present study some characteristics of the virulence of B. bronchiseptica isolates of different origin were studied. All isolates had similar phenotypes, similar bacteriological characters, and synthesized adenylate cyclase-hemolysin, filamentous hemagglutinin and pertactin but not pertussis toxin. These isolates, however, differed in their ability to express dermonecrotic toxin and to cause a lethal infection, but no correlation was found with the human or animal origin of the isolates. The fact that the most virulent isolate did not express dermonecrotic toxin suggests that this toxin does not play an important role in the virulence of the bacteria in the murine model. After infection with virulent B. bronchiseptica a very early synthesis and a persistence of anti-adenylate cyclase-hemolysin and anti-filamentous hemagglutinin antibodies were observed in the sera of infected mice, suggesting a persistence of the bacteria or of its antigens. B. bronchiseptica adenylate cyclase-hemolysin was purified and was shown to be a major protective antigen against B. bronchiseptica infection. Furthermore, we showed that its immunological and protective properties were different from that of B. pertussis adenylate cyclase-hemolysin, confirming that Bordetella species are immunologically different.

Adenylyl Cyclases↗
PubMed1993

Bordetella pertussis and Bordetella parapertussis: two immunologically distinct species.

Bordetella pertussis and Bordetella parapertussis are closely related species. Both are responsible for outbreaks of whooping cough in humans and produce similar virulence factors, with the exception of pertussis toxin, specific to B. pertussis. Current pertussis whole-cell vaccine will soon be replaced by acellular vaccines containing major adhesins (filamentous hemagglutinin and pertactin) and major toxin (pertussis toxin). All of these factors are antigens that stimulate a protective immune response in the murine respiratory model and in clinical assays. In the present study, we examined the protective efficacies of these factors, and that of adenylate cyclase-hemolysin, another B. pertussis toxin, against B. parapertussis infection in a murine respiratory model. As expected, pertussis toxin did not protect against B. parapertussis infection, since this bacterium did not express this protein, but the surprising result was that none of the other factors were protective against B. parapertussis infection. Furthermore, B. parapertussis adenylate cyclase-hemolysin, although it protected against B. parapertussis infection, did not protect against B. pertussis infection. Despite a high degree of homology between both B. pertussis and B. parapertussis species, no cross-protection was observed. Our results outline the fact that, as in other gram-negative bacteria, Bordetella surface proteins vary immunologically.

Adenylate Cyclase Toxin↗