Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
Mais filtros

Base de dados
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
J Dairy Sci ; 101(9): 8301-8307, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29908808

RESUMO

Digital dermatitis is an infectious disease of cattle and the leading cause of lameness. This disease is complicated by the reoccurrence of the lesions and the observation of lesions on more than one limb at different time points, indicating infection may not result in a protective immune response. The objective of this study was to characterize the peripheral blood cellular response in naturally infected and naïve cattle to bacterial antigens derived from pathogens associated with digital dermatitis lesions. Peripheral blood mononuclear cells were isolated from dairy cattle identified as having active or chronic lesions during routine hoof-trimming. Following bacterial antigen stimulation, cells were analyzed for proliferation and phenotype by flow cytometry, and culture supernatants were analyzed for IFN-γ secretion. Digital-dermatitis-infected animals had greater serum antibody titers to treponemal antigens, higher percentages of proliferating CD8+, γδ-T cells, and B cells, and increased IFN-γ secretion in vitro when compared with responses of naïve animals. No increase in proliferation of CD4+ T cells was detected in infected or naïve cattle. Although CD8+ and γδ-T cell responses may be antigen specific, the memory nature or long-lived response is yet unknown. The lack of responsiveness of CD4+ memory cells to treponemal antigens could explain the high rate of reoccurrence of digital dermatitis in infected animals.


Assuntos
Doenças dos Bovinos/imunologia , Dermatite Digital/imunologia , Ativação Linfocitária , Animais , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Bovinos , Interferon gama , Leucócitos Mononucleares , Receptores de Antígenos de Linfócitos T gama-delta/imunologia
2.
Appl Environ Microbiol ; 77(20): 7158-66, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21821757

RESUMO

Megasphaera elsdenii is a lactate-fermenting, obligately anaerobic bacterium commonly present in the gastrointestinal tracts of mammals, including humans. Swine M. elsdenii strains were previously shown to have high levels of tetracycline resistance (MIC=64 to >256 µg/ml) and to carry mosaic (recombinant) tetracycline resistance genes. Baby pigs inherit intestinal microbiota from the mother sow. In these investigations we addressed two questions. When do M. elsdenii strains from the sow colonize baby pigs? Can five antibiotic-sensitive M. elsdenii strains administered intragastrically to newborn pigs affect natural colonization of the piglets by antibiotic-resistant (AR) M. elsdenii strains from the mother? M. elsdenii natural colonization of newborn pigs was undetectable (<10(4) CFU/g [wet weight] of feces) prior to weaning (20 days after birth). After weaning, all pigs became colonized (4 × 10(5) to 2 × 10(8) CFU/g feces). In a separate study, 61% (76/125) of M. elsdenii isolates from a gravid sow never exposed to antibiotics were resistant to chlortetracycline, ampicillin, or tylosin. The inoculation of the sow's offspring with mixtures of M. elsdenii antibiotic-sensitive strains prevented colonization of the offspring by maternal AR strains until at least 11 days postweaning. At 25 and 53 days postweaning, however, AR strains predominated. Antibiotic susceptibility phenotypes and single nucleotide polymorphism (SNP)-based identities of M. elsdenii isolated from sow and offspring were unexpectedly diverse. These results suggest that dosing newborn piglets with M. elsdenii antibiotic-sensitive strains delays but does not prevent colonization by maternal resistant strains. M. elsdenii subspecies diversity offers an explanation for the persistence of resistant strains in the absence of antibiotic selection.


Assuntos
Antibiose , Farmacorresistência Bacteriana , Trato Gastrointestinal/microbiologia , Megasphaera/crescimento & desenvolvimento , Probióticos/administração & dosagem , Animais , Animais Recém-Nascidos , Antibacterianos/farmacologia , Carga Bacteriana , Sequência de Bases , DNA Bacteriano/química , DNA Bacteriano/genética , Fezes/microbiologia , Megasphaera/efeitos dos fármacos , Megasphaera/isolamento & purificação , Dados de Sequência Molecular , Análise de Sequência de DNA , Suínos
3.
Appl Environ Microbiol ; 77(20): 7167-70, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21821750

RESUMO

Organically raised swine had high fecal populations of chlortetracycline (CTC)-resistant (growing at 64 µg CTC/ml) Escherichia coli, Megasphaera elsdenii, and anaerobic bacteria. By comparison, CTC-resistant bacteria in feral swine feces were over 1,000-fold fewer and exhibited lower taxonomic diversity.


Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Clortetraciclina/farmacologia , Farmacorresistência Bacteriana , Trato Gastrointestinal/microbiologia , Animais , Bactérias/classificação , Bactérias/isolamento & purificação , Fezes/microbiologia , Suínos
4.
J Bacteriol ; 191(5): 1719-21, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19103931

RESUMO

The Brachyspira hyodysenteriae B204 genome sequence revealed three VSH-1 tail genes, hvp31, hvp60, and hvp37, in a 3.6-kb cluster. The location and transcription direction of these genes relative to those of the previously described VSH-1 16.3-kb gene operon indicate that the gene transfer agent VSH-1 has a noncontiguous, divided genome.


Assuntos
Bacteriófagos/genética , Brachyspira hyodysenteriae/virologia , Genoma Viral/genética , Prófagos/genética , Proteínas Virais/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Transferência Genética Horizontal , Dados de Sequência Molecular , Suínos
5.
Appl Environ Microbiol ; 74(10): 2950-6, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18359835

RESUMO

Brachyspira hyodysenteriae is an anaerobic spirochete and the etiologic agent of swine dysentery. The genome of this spirochete contains a mitomycin C-inducible, prophage-like gene transfer agent designated VSH-1. VSH-1 particles package random 7.5-kb fragments of the B. hyodysenteriae genome and transfer genes between B. hyodysenteriae cells. The chemicals and conditions inducing VSH-1 production are largely unknown. Antibiotics used in swine management and stressors inducing traditional prophages might induce VSH-1 and thereby stimulate lateral gene transfer between B. hyodysenteriae cells. In these studies, VSH-1 induction was initially detected by a quantitative real-time reverse transcriptase PCR assay evaluating increased transcription of hvp38 (VSH-1 head protein gene). VSH-1 induction was confirmed by detecting VSH-1-associated 7.5-kb DNA and VSH-1 particles in B. hyodysenteriae cultures. Nine antibiotics (chlortetracycline, lincomycin, tylosin, tiamulin, virginiamycin, ampicillin, ceftriaxone, vancomycin, and florfenicol) at concentrations affecting B. hyodysenteriae growth did not induce VSH-1 production. By contrast, VSH-1 was detected in B. hyodysenteriae cultures treated with mitomycin C (10 microg/ml), carbadox (0.5 microg/ml), metronidazole (0.5 microg/ml), and H(2)O(2) (300 microM). Carbadox- and metronidazole-induced VSH-1 particles transmitted tylosin and chloramphenicol resistance determinants between B. hyodysenteriae strains. The results of these studies suggest that certain antibiotics may induce the production of prophage or prophage-like elements by intestinal bacteria and thereby impact intestinal microbial ecology.


Assuntos
Antibacterianos/farmacologia , Brachyspira hyodysenteriae/efeitos dos fármacos , Brachyspira hyodysenteriae/genética , Carbadox/farmacologia , Metronidazol/farmacologia , Prófagos/efeitos dos fármacos , Transdução Genética , Bacteriófagos/efeitos dos fármacos , Bacteriófagos/crescimento & desenvolvimento , Bacteriófagos/ultraestrutura , Brachyspira hyodysenteriae/crescimento & desenvolvimento , Brachyspira hyodysenteriae/virologia , Meios de Cultura/química , DNA Viral/análise , Farmacorresistência Bacteriana/genética , Genes Virais , Peróxido de Hidrogênio/farmacologia , Microscopia Eletrônica de Transmissão , Mitomicina/farmacologia , Reação em Cadeia da Polimerase , RNA Viral/biossíntese , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica/efeitos dos fármacos , Proteínas Virais/genética
6.
FEMS Microbiol Lett ; 224(2): 225-9, 2003 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-12892886

RESUMO

VSH-1 is a mitomycin C-inducible, non-lytic, phage-like agent that packages random 7.5-kb fragments of the Brachyspira hyodysenteriae genome. VSH-1 is the first recognized mechanism for gene transfer between B. hyodysenteriae cells. To analyze the distribution of VSH-1 among spirochetes, a 344-bp probe for gene svp38, encoding the VSH-1 major head protein, was amplified by polymerase chain reaction and used in Southern blot hybridizations with genomic DNA from various spirochete genera. The svp38 probe hybridized to a 40-kb SalI-SmaI fragment of the B. hyodysenteriae B78(T) chromosome, indicating VSH-1 DNA insertion into the chromosome at a unique site. Restriction endonuclease digested DNAs of 27 spirochete strains representing six Brachyspira species (B. hyodysenteriae, B. innocens, B. pilosicoli, B. murdochii, B. intermedia, B. alvinipulli) contained a single fragment hybridizing with the svp38 probe. DNAs from spirochete species of the genera Treponema, Spirochaeta, Borrelia, and Leptospira did not hybridize with the probe. VSH-1-like agents appear to be widely distributed among Brachyspira species and, as has been demonstrated for B. hyodysenteriae, may serve as useful gene transfer agents for those other species.


Assuntos
Bacteriófagos/genética , Spirochaetaceae/genética , Spirochaetaceae/virologia , Genoma Viral , Dados de Sequência Molecular , Prófagos/genética , Transdução Genética , Proteínas Virais/genética
7.
J Bacteriol ; 187(17): 5885-92, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16109929

RESUMO

VSH-1 is a mitomycin C-inducible prophage of the anaerobic spirochete Brachyspira hyodysenteriae. Purified VSH-1 virions are noninfectious, contain random 7.5-kb fragments of the bacterial genome, and mediate generalized transduction of B. hyodysenteriae cells. In order to identify and sequence genes of this novel gene transfer agent (GTA), proteins associated either with VSH-1 capsids or with tails were purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminal amino acid sequences of 11 proteins were determined. Degenerate PCR primers were designed from the amino acid sequences and used to amplify several VSH-1 genes from B. hyodysenteriae strain B204 DNA. A lambda clone library of B. hyodysenteriae B204 DNA was subsequently screened by Southern hybridization methods and used to identify and sequence overlapping DNA inserts containing additional VSH-1 genes. VSH-1 genes spanned 16.3 kb of the B. hyodysenteriae chromosome and were flanked by bacterial genes. VSH-1 identified genes and unidentified, intervening open reading frames were consecutively organized in head (seven genes), tail (seven genes), and lysis (four genes) clusters in the same transcriptional direction. Putative lysis genes encoding endolysin (Lys) and holin proteins were identified from sequence and structural similarities of their translated protein products with GenBank bacteriophage proteins. Recombinant Lys protein hydrolyzed peptidoglycan purified from B. hyodysenteriae cells. The identified VSH-1 genes exceed the DNA capacity of VSH-1 virions and do not encode traditional bacteriophage early functions involved in DNA replication. These genome properties explain the noninfectious nature of VSH-1 virions and further confirm its resemblance to known prophage-like, GTAs of other bacterial species, such as the GTA from Rhodobacter capsulatus. The identification of VSH-1 genes will enable analysis of the regulation of this GTA and should facilitate investigations of VSH-1-like prophages from other Brachyspira species.


Assuntos
Técnicas de Transferência de Genes , Prófagos/genética , Spirochaetales/genética , Clonagem Molecular , DNA Viral/química , DNA Viral/genética , Genoma Bacteriano , Cinética , Dados de Sequência Molecular , Peso Molecular , Spirochaetales/virologia , Proteínas Virais/química , Proteínas Virais/genética , Proteínas Virais/isolamento & purificação , Vírion/genética , Vírion/ultraestrutura
8.
Appl Environ Microbiol ; 69(7): 3874-82, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12839756

RESUMO

Anaerobic bacteria insensitive to chlortetracycline (64 to 256 microg/ml) were isolated from cecal contents and cecal tissues of swine fed or not fed chlortetracycline. A nutritionally complex, rumen fluid-based medium was used for culturing the bacteria. Eight of 84 isolates from seven different animals were identified as Megasphaera elsdenii strains based on their large-coccus morphology, rapid growth on lactate, and 16S ribosomal DNA sequence similarities with M. elsdenii LC-1(T). All eight strains had tetracycline MICs of between 128 and 256 microg/ml. Based on PCR assays differentiating 14 tet classes, the strains gave a positive reaction for the tet(O) gene. By contrast, three ruminant M. elsdenii strains recovered from 30-year-old culture stocks had tetracycline MICs of 4 microg/ml and did not contain tet genes. The tet genes of two tetracycline-resistant M. elsdenii strains were amplified and cloned. Both genes bestowed tetracycline resistance (MIC = 32 to 64 microg/ml) on recombinant Escherichia coli strains. Sequence analysis revealed that the M. elsdenii genes represent two different mosaic genes formed by interclass (double-crossover) recombination events involving tet(O) and tet(W). One or the other genotype was present in each of the eight tetracycline-resistant M. elsdenii strains isolated in these studies. These findings suggest a role for commensal bacteria not only in the preservation and dissemination of antibiotic resistance in the intestinal tract but also in the evolution of resistance.


Assuntos
Bactérias Anaeróbias/isolamento & purificação , Proteínas de Bactérias/genética , Proteínas de Transporte/genética , Cocos Gram-Positivos/isolamento & purificação , Recombinação Genética , Resistência a Tetraciclina/genética , Animais , Antibacterianos/farmacologia , Bactérias Anaeróbias/classificação , Bactérias Anaeróbias/efeitos dos fármacos , Bactérias Anaeróbias/genética , Ceco/microbiologia , Clortetraciclina/farmacologia , Meios de Cultura , DNA Ribossômico/análise , Evolução Molecular , Cocos Gram-Positivos/classificação , Cocos Gram-Positivos/efeitos dos fármacos , Cocos Gram-Positivos/genética , Lactatos/metabolismo , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Suínos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA