Survey of equine hepatic encephalopathy in France in 1992.
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Animals↗
Biomedical subjects
B Gicquel
Publications and source records attributed to B Gicquel.
Follow-up of tuberculosis patients undergoing standard anti-tuberculosis chemotherapy by using a polymerase chain reaction.
We have analysed the clearance of Mycobacterium tuberculosis in sputum specimens from pulmonary tuberculosis patients undergoing 6-month chemotherapy, using the polymerase chain reaction (PCR) and standard microbiological methods. In a group of 19 patients, 11 (58%) were smear- or culture-positive and 13 (74%) were PCR-positive before treatment. Of the 16 patients followed from 2 months after the start of treatment and thereafter, all became smear-negative and culture-negative, whereas, with PCR, 4 (27%), 2 (13%) and 1 (7%) of these patients remained positive after 2, 3 and 6 months, respectively. These results suggest the possible usefulness of PCR in monitoring the efficacy of treatment when bacteriological tests are negative, so as to identify patients with a high risk of relapse.
Anti-Bacterial Agents↗
Insertion sequence IS1137, a new IS3 family element from Mycobacterium smegmatis.
A new insertion sequence (IS) has been isolated from Mycobacterium smegmatis. It is 1361 bp long and possesses characteristics of the IS3 family elements. It harbours 32 bp imperfect inverted repeats at its extremities and a 3 bp direct repeat flanks the element, possibly as the result of a transposition event. This IS, IS1137, contains three major ORFs. Two of them, ORF A and ORF B show homologies both at the amino acid sequence level and at the organization level with the ORFs encoding the transposase of the IS3 family elements. IS1137 has a narrow host range and was found only in M. smegmatis and M. chitae. The fact that IS1137 is not present in the M. tuberculosis complex strains makes this element a new candidate for transposon mutagenesis in mycobacteria.
Amino Acid Sequence↗
Efficient transposition in mycobacteria: construction of Mycobacterium smegmatis insertional mutant libraries.
The Tn611 transposon was inserted into pCG63, a temperature-sensitive plasmid isolated from an Escherichia coli-mycobacterial shuttle vector which contains the pAL5000 and pUC18 replicons. The resulting plasmid, pCG79, was used to generate a large number of insertional mutations in Mycobacterium smegmatis. These are the first mycobacterial insertional mutant libraries to be constructed by transposition directly into a mycobacterium. No highly preferential insertion sites were detected by Southern blot analysis of the chromosomal DNAs isolated from the insertion mutants. Auxotrophic mutants with various phenotypes were isolated at a frequency ranging from 0.1 to 0.4%, suggesting that the libraries are representative. The pCG79 system thus seems to be a useful tool for the study of M. smegmatis genetics and may be applicable to other mycobacteria, such as the M. tuberculosis complex.
Amino Acids↗
Escherichia coli-mycobacteria shuttle vectors for operon and gene fusions to lacZ: the pJEM series.
A series of Escherichia coli-mycobacteria shuttle plasmids for the isolation and study of gene regulatory sequences was constructed. These pJEM vectors contain an efficient transcription terminator and multiple cloning sites and allow either operon or gene fusions to lacZ. By constructing operon fusions with pJEM15, we assessed various previously characterized mycobacterial promoters in the fast-growing species Mycobacterium smegmatis and the slow-growing species M. bovis BCG. Our results suggest that M. smegmatis and M. bovis BCG RNA polymerases do not share the same specificity. To isolate new mycobacterial promoters, an M. tuberculosis DNA library was generated, using pJEM13, and screened in M. smegmatis. Several Lac+ clones were isolated, and the beta-galactosidase activity was measured.
Base Sequence↗
Genetic control of susceptibility to leprosy in French Polynesia; no evidence for linkage with markers on telomeric human chromosome 2.
Several lines of evidence have suggested a role of genetic factors in susceptibility to leprosy. In the mouse, natural susceptibility to infection with mycobacteria is controlled by the chromosome 1 Bcg locus, a region which is syntenic with a fragment of the human chromosome 2q, region q31-q37. It has been postulated that a human homolog of the Bcg gene controls susceptibility to leprosy per se, and may be located on chromosome 2q. In order to test the influence of this putative gene on leprosy per se, we performed linkage analyses in a set of seven multicase French Polynesian pedigrees, using an affected sib pair method and the LOD score method employing different modes of inheritance. Family members were typed for eight polymorphic loci on chromosome 2q: CRYGP1, FN, TNP1, VIL, DES, INH, PAX3, and UGT1A1. Our data provide evidence against the presence of a gene controlling susceptibility to leprosy per se on human chromosome 2q in the French Polynesian population.
Chromosomes, Human, Pair 2↗
Towards new mycobacterial vaccines.
BCG, the Bacillus of Calmette and Guérin, has been used as a vector for the presentation of foreign antigens. The nef gene of HIV was cloned and expressed in BCG. A specific cellular immune response against Nef was observed following inoculation of mice. As a model system beta-galactosidase has also been expressed in BCG. Antibody responses against beta-galactosidase in addition to cellular responses were observed. Mucosal immunity was demonstrated after oral immunization of mice. With the aim of isolating new vaccines against tuberculosis, transposon mutagenesis was investigated. By using Tn610, representative libraries of Mycobacterium smegmatis insertion mutants were constructed.
AIDS Vaccines↗
Oral immunization with recombinant BCG induces cellular and humoral immune responses against the foreign antigen.
It has been shown recently that BCG can be used as a live recombinant vaccine to stimulate immune responses. Proliferative or cytotoxic T-cell responses against several viral proteins such as HIV Gag, Env or Nef were obtained after parenteral immunization with BCG expressing these proteins. Antibody responses were also obtained after immunization of mice with recombinant BCG strain which expressed lac Z under the control of a promoter sequence isolated from Mycobacterium paratuberculosis. We have used this recombinant vaccine in guinea-pigs to investigate the influence of various routes of immunization on the immunogenicity of a foreign antigen expressed by recombinant BCG. Guinea-pigs were immunized by oral, respiratory or intradermal routes and proliferative responses, delayed-type hypersensitivity and antibody responses specific for beta-galactosidase were followed for 16 weeks. Results demonstrated that humoral and cellular immune responses specific for beta-galactosidase can be produced in all groups of guinea-pigs. However, the respiratory and especially the oral route of administration induced higher local and systemic immune responses than the intradermal route of immunization. Moreover, the oral immunization of mice with this recombinant BCG induced IgA responses which could be detected in both sera and intestinal secretions. Therefore, this study demonstrates for the first time that oral immunization with recombinant BCG can induce strong cellular and humoral immune responses.
Administration, Inhalation↗
RFLP typing of the Mycobacterium tuberculosis bacilli.
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Humans↗
Strain identification of Mycobacterium tuberculosis by DNA fingerprinting: recommendations for a standardized methodology.
DNA fingerprinting of Mycobacterium tuberculosis has been shown to be a powerful epidemiologic tool. We propose a standardized technique which exploits variability in both the number and genomic position of IS6110 to generate strain-specific patterns. General use of this technique will permit comparison of results between different laboratories. Such comparisons will facilitate investigations into the international transmission of tuberculosis and may identify specific strains with unique properties such as high infectivity, virulence, or drug resistance.
Base Sequence↗
Large-scale DNA fingerprinting of Mycobacterium tuberculosis strains as a tool for epidemiological studies of tuberculosis.
We conducted a large-scale DNA fingerprinting analysis of Mycobacterium tuberculosis strains in a country in which tuberculosis is endemic (Tunisia) in order to evaluate the importance of microepidemics in the maintenance of the disease within the population. The genetic polymorphisms of 201 strains of M. tuberculosis isolated from 196 unrelated patients living in four districts of northern Tunisia during a 3-year period were studied by restriction fragment length polymorphism (RFLP) analysis by using the insertion sequence IS6110 as a probe. Seventy-three strains isolated from 68 patients living in the districts of Tunis, Nabeul, and Jendouba generated 67 different RFLPs, indicating a high degree of polymorphism of the M. tuberculosis strains within these areas. In contrast, the 128 strains isolated from individuals in the district of Menzel Bourguiba appeared much less heterogeneous since they often generated identical or very similar fingerprints. Seventeen of 29 cases (58%) of active tuberculosis in the city of Menzel Bourguiba could be traced to as few as four M. tuberculosis strains. These results indicate the persistence of underestimated microepidemics in this region. The RFLP typing of a large number of randomly collected strains provides a general picture of the strains involved in tuberculosis. The systematic study of limited areas where tuberculosis is endemic can provide evidence for the existence of persisting epidemics. This stresses the different problems which remain to be solved in order to improve the control of tuberculosis.
DNA Fingerprinting↗
Temperature-sensitive mutants of the Mycobacterium plasmid pAL5000.
Two plasmids were isolated as thermosensitive replicons following in vitro mutagenesis of pB4, a pAL5000 derivative mycobacteria/Escherichia coli shuttle plasmid. Plasmids pCG59 and pCG63 replicate at 30 degrees C but not at 39 degrees C. This will allow their utilisation for transposon delivery, site-specific integration, or allele exchange.
Escherichia coli↗
Analysis of the regions responsible for IS6110 RFLP in a single Mycobacterium tuberculosis strain.
A high degree of IS6110 restriction fragment length polymorphism (RFLP) is observed amongst the different strains of the Mycobacterium tuberculosis complex. The sequences of the IS6110 flanking regions from a M. tuberculosis strain harbouring four IS6110 copies were determined. Duplication of 3-4 nucleotides was found at the extremities of the four IS6110 copies, suggesting that IS6110 RFLP is due to transposition of the IS element. One of the copies of IS6110 analysed in the study was shown to be located at the same site in the genome of M. tuberculosis as the single copy present in an M. bovis BCG strain.
Base Sequence↗
Isolation and analysis of IS6120, a new insertion sequence from Mycobacterium smegmatis.
Insertion sequence IS6120 from Mycobacterium smegmatis was identified by its ability to transpose into different sites in the lambda repressor gene, cl857, carried on an Escherichia coli/mycobacteria shuttle plasmid. IS6120 is a novel 1.5 kb insertion sequence, which has 24-bp imperfect terminal inverted repeats and generates 9-bp duplications of the target DNA following insertion. IS6120 is present in at least three copies in M. smegmatis but was not found in other species, including Mycobacterium tuberculosis. Nucleotide sequence analysis revealed that IS6120 contains two open reading frames, one of which encodes a putative transposase with similarities to those found in IS256 from Staphylococcus aureus, IST2 from Thiobacillus ferrooxidans, and ISRm3 from Rhizobium meliloti. The fact that IS6120 does not recognize a consensus target sequence for insertion and has no homologous sequences in the other strains studied makes IS6120 useful for transposon mutagenesis in mycobacteria.
Amino Acid Sequence↗
Expression of Escherichia coli beta-galactosidase in Mycobacterium bovis BCG using an expression system isolated from Mycobacterium paratuberculosis which induced humoral and cellular immune responses.
A promoter sequence, PAN, was isolated from Mycobacterium paratuberculosis and characterized. This promoter lies adjacent to, and outside, the 3' end of an IS900 insertion element. IS900 contains an open reading frame, ORF2, on the complementary strand which codes for the putative transposase of this insertion sequence. A DNA fragment containing PAN and part of ORF2 was fused to the lacZ gene and inserted into the replicative shuttle vector pRR3. Mycobacterium smegmatis and Mycobacterium bovis BCG (BCG) transformed with this plasmid exhibited beta-galactosidase activity. However, lacZ was only expressed in Escherichia coli under the control of PAN, when ORF2 was deleted. Immunization of mice with the recombinant M. bovis BCG expressing lacZ resulted in the induction of a high humoral and cellular response directed against beta-galactosidase. The PAN-ORF2 expression system may prove to be particularly useful for cloning and expression of heterologous genes in the BCG vaccine strain.
Amino Acid Sequence↗
Expression of heterologous genes in Mycobacterium bovis BCG: induction of a cellular response against HIV-1 Nef protein.
Mycobacterium bovis bacillus Calmette-Guérin (BCG) has been used as a live bacterial vaccine to immunize more than two billion people against tuberculosis. In an attempt to use this vaccinal strain as a vehicle for protective antigens, the human immunodeficiency virus type 1 gene encoding the Nef protein was cloned in a mycobacteria-Escherichia coli shuttle plasmid and transferred into BCG. The nef gene was expressed under the control of an expression cassette carrying the promoter of the groES/groEL1 operon from Streptomyces albus and a synthetic ribosome-binding site. Lymph node cells from mice immunized with BCG-nef proliferated vigorously in response to purified Nef protein. This first report of a proliferative response suggests that recombinant BCG strains may be used to immunize against pathogens for which T-cell-mediated responses are important for protection.
Gene Products, nef↗
Diagnosis of tuberculosis by DNA amplification in clinical practice evaluation.
Various polymerase chain reaction (PCR) assays have been devised for the rapid identification of mycobacteria in clinical specimens. To assess the value of such assays in routine laboratory work the results obtained by PCR were compared with those obtained by standard microbiological methods for 514 specimens collected for investigation of mycobacterial infection. Specimens were tested for the presence of Mycobacterium tuberculosis complex and atypical mycobacteria in two assays, one based on amplification of the 65 kDa gene and the other on the IS6110 insertion sequence. For the 489 samples that did not contain inhibitors of the amplification reaction PCR findings correlated well with bacteriological and/or clinical data in 476 (97.4%). 6 PCR results turned out to be false negatives, 3 to be false positives and 4 to be mis-identification of strains. Pre-treatment of samples with guanidium thiocyanate reduced the proportion of false-negative results and of samples that contained inhibitors. This study confirms the potential of DNA amplification for early diagnosis of mycobacterial infections.
DNA Probes↗
Site-specific integration of the Streptomyces plasmid pSAM2 in Mycobacterium smegmatis.
A method which allowed the stable integration of DNA fragments at a single site (attB) in the chromosome of Mycobacterium smegmatis was developed using an integrative element from Streptomyces ambofaciens, pSAM2. Vectors containing an Escherichia coli replicon (pBR322), the kanamycin resistance gene from Tn903 for selection in mycobacteria, and a fragment of pSAM2 containing the int gene as well as the attachment site (attP) were constructed and introduced to M. smegmatis by electroporation. Transformants showed stable integration of the plasmid into a single site (attB) of the mycobacterial genome. This approach should be valuable for analyses of gene expression in various mycobacterial species and permit the development of stable recombinant mycobacterial vaccine strains expressing bacterial or viral genes inserted in pSAM2.
Blotting, Southern↗