Explore the vast range of titles available.

Many non-tuberculous mycobacteria synthesize abundant glycopeptidolipids (GPLs). These surface-located GPLs are involved in pathogenicity by interfering with the host immune system. In Mycobacterium avium subsp. avium ( Mav), GPLs consist of a lipopeptide core composed of a tetrapeptide O-linked to mono- and oligo-saccharides. The biosynthesis pathway of the simplest GPLs is now relatively well understood and involves probably more than fifteen genes. Whereas it is very obvious that most, if not all, of the Mav isolates produce GPLs, the picture is not as clear for M. avium subsp. paratuberculosis ( Map), the etiologic agent of Johne's disease in cattle, and several conflicting data have been produced. Biochemical analysis of a large set of characterized Map isolates showed that all Map strains tested produce a lipopentapeptide (L5P) instead of GPLs. To provide a genomic basis for the synthesis of this compound, the recently published genome sequence of Map was explored using in silico methods. Even though Map produces a lipopeptide rather than GPL, its genome contains nevertheless a locus highly similar to the GPL biosynthetic pathway of Mav. We showed that the module composition of the non-ribosomal protein synthase (Nrp) of Map, the enzyme involved in the synthesis of the peptidyl moiety, is dramatically different from that of other GPL producers such as M. smegmatis ( Ms) and Mav and is in agreement with the amino acid content of the L5P. We also showed that the peptidyl moiety of the L5P is a target for a strong specific humoral response in Map infected animals. These genomic and biochemical differences may help to unambiguously distinguish Map from Mav and also from M. bovis, to reclassify related strains of the Map species and to allow the convenient and specific diagnosis of paratuberculosis.

The commonly used live attenuated vaccine in ovine brucellosis prophylaxis is Brucella melitensis Rev. 1. This vaccine is known to induce antibody responses in vaccinated animals indistinguishable by the current conventional serological tests from those observed in challenged animals. Brucella BP26 and Omp31 proteins have shown an interesting potential as diagnostic antigens for ovine brucellosis. Accordingly, the bp26 gene and both bp26 and omp31 genes have been deleted from the vaccine strain Rev. 1. Immunogenicity and vaccine efficacy of the parental Rev. 1 strain and of both mutants in protecting sheep against B. inelitensis strain H38 challenge was evaluated by clinical and bacteriological examination of ewes. They were conjunctivally or subcutaneously vaccinated when 4 months old and then challenged with B. melitensis H38 at the middle of the first pregnancy following vaccination. Deletion of bp26 and omp31 genes did not significantly affect the well recognised capacity of Rev. 1 to protect sheep against B. melitensis challenge. However, the protection conferred by the CGV2631 mutant was significantly lower than that conferred by the CGV26 mutant or the Rev. I strain. Vaccinated and challenged animals were detected positive in classical serological tests and in the IFN-gamma assay. A BP26-based ELISA was investigated to discriminate between ewes vaccinated by the mutants and ewes challenged with B. inelitensis H38. The cut-off which was chosen in order to have 100% specificity resulted in a moderate sensitivy for the detection of challenged ewes. The use in the field of one of the mutants as vaccine against a B. inelitensis infection, combined with classic diagnostic tests and a BP26 ELISA, could thus give an improvement in the differentiation between vaccinated and infected animals and contribute to the objective of eradication of brucellosis in small ruminants. (c) 2006 Elsevier Ltd. All rights reserved.

The live attenuated strain B. melitensis Rev.1 is considered the best vaccine available for the prophylaxis of brucellosis in sheep and goats. The Rev.1 vaccine was obtained in the 1950s by a two-step selection involving firstly streptomycin resistance and dependence and secondly reversion of dependence but keeping streptomycin resistance. Chromosomally acquired streptomycin resistance is frequently due to mutations in the gene encoding the ribosomal protein S12, rpsL. Nucleotide sequencing revealed one mutation in the rpsL gene of vaccine strain Rev.1 compared to that of reference strain 16 M leading to an amino acid Pro-to-Leu change at codon position 91 (Pro91Leu). This mutation resulted also in the lack of a NciI restriction site in the gene. PCR-restriction fragment length polymorphism (PCR-RFLP) using NciI applied to a large number of Brucella reference and field strains showed that the mutation detected was specific of vaccine strain Rev.1.

The commonly used live attenuated vaccine in ovine brucellosis prophylaxis is Brucella melitensis Rev.1. This vaccine is known to induce antibody responses in vaccinated animals indistinguishable by the current conventional serological tests from those observed in challenged animals. Brucella BP26 and Omp31 proteins have shown an interesting potential as diagnostic antigens for ovine brucellosis. Accordingly, the bp26 gene and both bp26 and omp31 genes have been deleted from the vaccine strain Rev.1. Immunogenicity and vaccine efficacy of the parental Rev.1 strain and of both mutants in protecting sheep against B. melitensis strain H38 challenge was evaluated by clinical and bacteriological examination of ewes. They were conjunctivally or subcutaneously vaccinated when 4 months old and then challenged with B. melitensis H38 at the middle of the first pregnancy following vaccination. Deletion of bp26 and omp31 genes did not significantly affect the well recognised capacity of Rev.1 to protect sheep against B. melitensis challenge. However, the protection conferred by the CGV2631 mutant was significantly lower than that conferred by the CGV26 mutant or the Rev.1 strain. Vaccinated and challenged animals were detected positive in classical serological tests and in the IFN-γ assay. A BP26-based ELISA was investigated to discriminate between ewes vaccinated by the mutants and ewes challenged with B. melitensis H38. The cut-off which was chosen in order to have 100% specificity resulted in a moderate sensitivy for the detection of challenged ewes. The use in the field of one of the mutants as vaccine against a B. melitensis infection, combined with classic diagnostic tests and a BP26 ELISA, could thus give an improvement in the differentiation between vaccinated and infected animals and contribute to the objective of eradication of brucellosis in small ruminants.

Since the 1990s, Brucella strains not matching the characteristics of any of the six conventional species have been isolated worldwide from marine mammals. In this study, 31 Brucella strains isolated from various marine mammals were examined for their oxidative metabolic pattern on 12 amino-acid and carbohydrate substrates. Three main oxidative profiles different from those of the Brucella terrestrial mammal strains were identified for the marine mammal strains: one gathering strains isolated from pinnipeds and two gathering strains from cetaceans. Thus, both oxidative metabolism results and previous molecular studies are in agreement with the proposal of two new Brucella species, Brucella pinnipediae and Brucella cetaceae, to classify the Brucella strains isolated from marine mammals, and are also in accordance with a classification of species of the Brucella genus based on host preference.

The live attenuated Brucella melitensis Rev.1 strain is considered the best vaccine available for the prophylaxis of brucellosis in sheep caused by either B. melitensis or Brucella ovis. However, its application stimulates antibody responses in vaccinated animals indistinguishable by the current conventional serological tests from those observed in infected animals. The periplasmic protein BP26 and the outer membrane protein (OMP) Omp31 are immunodominant antigens in the serological responses of B. melitensis and B. ovis infected sheep, respectively. Accordingly, vaccine strain Rev.1 single and double deletion mutants of the bp26 and omp31 genes were developed, based on the principle that the use of such mutants as vaccines in association with diagnostic tests based on BP26 and Omp31 antigens would allow the serological differentiation between infected and vaccinated animals. The deletion mutants obtained were indistinguishable from the parental Rev.1 strain by conventional bacteriological and typing tests. The expression of their major surface antigens, as determined by reactivity with specific monoclonal antibodies (MAbs), remained unaffected, i.e. smooth-lipopolysaccharide (S-LPS) and OMPs besides in the expression of the antigens whose respective genes were deleted. The bp26 and omp31 deletions did not modify the kinetics of splenic infection nor the residual virulence of Rev.1 in the BALB/c mouse model. Vaccination of BALB/c mice with the deletion mutants conferred significant protective immunity against B. melitensis strain H38 or B. ovis strain PA challenges, to the same extent as that induced by parental Rev.1 strain. Thus, these Rev.1 bp26 or omp31 deletion mutants are promising vaccine candidates against B. melitensis and B. ovis infections and will be further evaluated in sheep.

Background Many non-tuberculous mycobacteria synthesize abundant glycopeptidolipids (GPLs). These surface-located GPLs are involved in pathogenicity by interfering with the host immune system. InMycobacterium aviumsubsp.avium(Mav), GPLs consist of a lipopeptide core composed of a tetrapeptideO-linked to mono- and oligo-saccharides. The biosynthesis pathway of the simplest GPLs is now relatively well understood and involves probably more than fifteen genes. Whereas it is very obvious that most, if not all, of theMavisolates produce GPLs, the picture is not as clear forM.aviumsubsp.paratuberculosis(Map), the etiologic agent of Johne's disease in cattle, and several conflicting data have been produced. Methods Biochemical analysis of a large set of characterizedMapisolates showed that allMapstrains tested produce a lipopentapeptide (L5P) instead of GPLs. To provide a genomic basis for the synthesis of this compound, the recently published genome sequence ofMapwas explored usingin silicomethods. Even thoughMapproduces a lipopeptide rather than GPL, its genome contains nevertheless a locus highly similar to the GPL biosynthetic pathway ofMav.We showed that the module composition of the non-ribosomal protein synthase (Nrp) ofMap, the enzyme involved in the synthesis of the peptidyl moiety, is dramatically different from that of other GPL producers such asM. smegmatis(Ms) andMavand is in agreement with the amino acid content of the L5P. We also showed that the peptidyl moiety of the L5P is a target for a strong specific humoral response inMapinfected animals. Conclusions These genomic and biochemical differences may help to unambiguously distinguishMapfromMavand also fromM. bovis, to reclassify related strains of theMapspecies and to allow the convenient and specific diagnosis of paratuberculosis.

The commonly used live attenuated vaccine in ovine brucellosis prophylaxis isBrucella melitensisRev.1. This vaccine is known to induce antibody responses in vaccinated animals indistinguishable by the current conventional serological tests from those observed in challenged animals.BrucellaBP26 and Omp31 proteins have shown an interesting potential as diagnostic antigens for ovine brucellosis. Accordingly, thebp26gene and bothbp26andomp31genes have been deleted from the vaccine strain Rev.1. Immunogenicity and vaccine efficacy of the parental Rev.1 strain and of both mutants in protecting sheep againstB. melitensisstrain H38 challenge was evaluated by clinical and bacteriological examination of ewes. They were conjunctivally or subcutaneously vaccinated when 4 months old and then challenged withB. melitensisH38 at the middle of the first pregnancy following vaccination. Deletion ofbp26andomp31genes did not significantly affect the well recognised capacity of Rev.1 to protect sheep againstB. melitensischallenge. However, the protection conferred by the CGV2631 mutant was significantly lower than that conferred by the CGV26 mutant or the Rev.1 strain. Vaccinated and challenged animals were detected positive in classical serological tests and in the IFN-γ assay. A BP26-based ELISA was investigated to discriminate between ewes vaccinated by the mutants and ewes challenged withB. melitensisH38. The cut-off which was chosen in order to have 100% specificity resulted in a moderate sensitivy for the detection of challenged ewes. The use in the field of one of the mutants as vaccine against aB. melitensisinfection, combined with classic diagnostic tests and a BP26 ELISA, could thus give an improvement in the differentiation between vaccinated and infected animals and contribute to the objective of eradication of brucellosis in small ruminants.