RESUMEN
MIP and CPAF from Chlamydia have been shown to be effective in inducing immune responses important in clearing chlamydial infections. This study evaluates the protection conferred by MIP and CPAF as novel vaccines in pregnant C. abortus challenged ewes. Fifty C. abortus sero-negative sheep were randomly allocated into 5 groups of 10 according to the treatment they were to receive (1) 100⯵g of MBP-MIP (2) 100⯵g CPAF (3) 50⯵g MBP-MIP and 50⯵g CPAF (4) Tris-buffer (negative control) (5) Enzovax (positive control). Booster inoculations were administered 3â¯weeks after primary inoculations. Blood samples were taken pre-vaccination and weekly for 5â¯weeks. Five months after vaccination the ewes were mated. Pregnant ewes were then challenged on day 90 of gestation. Blood samples taken at four time-points post challenge were analysed for IFNγ levels, TNFα and IL-10 expression and anti-chlamydial antibody levels. Vaginal swabs, placental and foetal tissue and bacterial shedding were analysed using qPCR to quantify levels of C. abortus. Enzovax was 100% effective with no abortions occurring. The MIP/CPAF combined vaccine offered the greatest protection of the novel vaccines with 67% of ewes giving birth to one or more live lambs equating to a 50% vaccine efficacy rate. MIP and CPAF administered singly did not confer protection. Enzovax and MIP/CPAF vaccinated ewes had longer gestations and lambs with higher birth weights than negative control ewes. Aborting ewes shed higher numbers of C. abortus than ewes that had live lambs, all vaccinated ewes demonstrated lower levels of bacterial shedding than negative control ewes with Enzovax ewes shedding significantly fewer bacteria. Ewes that went on to abort had significantly higher levels of IFNγ and IL-10 at day 35 post challenge and significantly higher levels of anti-chlamydial antibodies at 24â¯h post lambing compared to ewes that had live lambs.
Asunto(s)
Infecciones por Chlamydia/inmunología , Infecciones por Chlamydia/prevención & control , Chlamydia/inmunología , Chlamydia/patogenicidad , Endopeptidasas/inmunología , Vacunación/métodos , Aborto Veterinario/prevención & control , Animales , Vacunas Bacterianas/inmunología , Vacunas Bacterianas/uso terapéutico , Endopeptidasas/metabolismo , Femenino , Embarazo , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , Ovinos , Enfermedades de las Ovejas/inmunología , Enfermedades de las Ovejas/prevención & controlRESUMEN
Intramammary infection (IMI) is one of the most costly diseases to the dairy industry. It is primarily due to bacterial infection and the major intramammary pathogens include Escherichia coli, Streptococcus uberis, and Staphylococcus aureus. The severity and outcome of IMI is dependent on several host factors including innate host resistance, energy balance, immune status, parity, and stage of lactation. Additionally, the infecting organism can influence the host immune response and progression of disease. It is increasingly recognized that not only the infecting pathogen species, but also the strain, can affect the transmission, severity, and outcome of IMI. For each of 3 major IMI-associated pathogens, S. aureus, Strep. uberis, and E. coli, specific strains have been identified that are adapted to the intramammary environment. Strain-dependent variation in the host immune response to infection has also been reported. The diversity of strains associated with IMI must be considered if vaccines effective against the full repertoire of mammary pathogenic strains are to be developed. Although important advances have been made recently in understanding the molecular mechanism underpinning strain-specific virulence, further research is required to fully elucidate the cellular and molecular pathogenesis of mammary adapted strains and the role of the strain in influencing the pathophysiology of infection. Improved understanding of molecular pathogenesis of strains associated with bovine IMI will contribute to the development of new control strategies, therapies, and vaccines. The development of enabling technologies such as pathogenomics, transcriptomics, and proteomics can facilitate system-level studies of strain-specific molecular pathogenesis and the identification of key mediators of host-pathogen interactions.
Asunto(s)
Infecciones por Escherichia coli/veterinaria , Escherichia coli/patogenicidad , Mastitis Bovina/microbiología , Infecciones Estafilocócicas/veterinaria , Staphylococcus aureus/patogenicidad , Infecciones Estreptocócicas/veterinaria , Streptococcus/patogenicidad , Animales , Bovinos , Industria Lechera , Infecciones por Escherichia coli/microbiología , Femenino , Interacciones Huésped-Patógeno , Lactancia , Paridad , Embarazo , Infecciones Estreptocócicas/microbiologíaRESUMEN
Gastrointestinal nematode infection is a constraint on sheep production worldwide. Selective breeding programmes to enhance resistance to nematode infection are currently being implemented in a number of countries. Identification of loci associated with resistance to infection or causative mutations for resistance would enable more effective selection. Loci associated with indicator traits for nematode resistance has been identified in previous studies. In this study, Scottish Blackface, Texel and Suffolk lambs were used to validate the effects at eight genomic regions previously associated with nematode resistance (OAR3, 4, 5, 7, 12, 13, 14, 21). No SNP was significantly associated with nematode resistance at the region-wide level but seven SNPs in three of the regions (OAR4, 12, 14) were nominally associated with trichostrongyle egg count in this study and six of these were also significant when fitted as single SNP effects. Nematodirus egg count was nominally associated with SNPs on OAR3, 4, 7 and 12.
Asunto(s)
Resistencia a la Enfermedad/genética , Infecciones por Nematodos/veterinaria , Enfermedades de las Ovejas/genética , Oveja Doméstica/genética , Animales , Cruzamiento , Sitios Genéticos , Infecciones por Nematodos/genética , Recuento de Huevos de Parásitos/veterinaria , Polimorfismo de Nucleótido Simple , Ovinos , Enfermedades de las Ovejas/parasitología , Oveja Doméstica/parasitologíaRESUMEN
Gastrointestinal nematode infection represents a major threat to the health, welfare and productivity of sheep populations worldwide. Infected lambs have a reduced ability to absorb nutrients from the gastrointestinal tract, resulting in morbidity and occasional mortality. The current chemo-dominant approach to nematode control is considered unsustainable due to the increasing incidence of anthelmintic resistance. In addition, there is growing consumer demand for food products from animals not subjected to chemical treatment. Future mechanisms of nematode control must rely on alternative, sustainable strategies such as vaccination or selective breeding of resistant animals. Such strategies take advantage of the host's natural immune response to nematodes. The ability to resist gastrointestinal nematode infection is considered to be dependent on the development of a protective acquired immune response, although the precise immune mechanisms involved in initiating this process remain to be fully elucidated. In this study, current knowledge on the innate and acquired host immune response to gastrointestinal nematode infection in sheep and the development of immunity is reviewed.
Asunto(s)
Enfermedades Gastrointestinales/veterinaria , Interacciones Huésped-Parásitos , Nematodos/inmunología , Infecciones por Nematodos/veterinaria , Enfermedades de las Ovejas/inmunología , Inmunidad Adaptativa , Animales , Antihelmínticos/uso terapéutico , Resistencia a Medicamentos , Enfermedades Gastrointestinales/tratamiento farmacológico , Enfermedades Gastrointestinales/inmunología , Inmunidad Innata , Infecciones por Nematodos/tratamiento farmacológico , Infecciones por Nematodos/inmunología , Ovinos , Enfermedades de las Ovejas/tratamiento farmacológicoRESUMEN
Rapid and accurate identification of mastitis pathogens is important for disease control. Bacterial culture and isolate identification is considered the gold standard in mastitis diagnosis but is time consuming and results in many culture-negative samples. Identification of mastitis pathogens by PCR has been proposed as a fast and sensitive alternative to bacterial culture. The results of bacterial culture and PCR for the identification of the aetiological agent of clinical mastitis were compared. The pathogen identified by traditional culture methods was also detected by PCR in 98 per cent of cases indicating good agreement between the positive results of bacterial culture and PCR. A mastitis pathogen could not be recovered from approximately 30 per cent of samples by bacterial culture, however, an aetiological agent was identified by PCR in 79 per cent of these samples. Therefore, a mastitis pathogen was detected in significantly more milk samples by PCR than by bacterial culture (92 per cent and 70 per cent, respectively) although the clinical relevance of PCR-positive culture-negative results remains controversial. A mixed infection of two or more mastitis pathogens was also detected more commonly by PCR. Culture-negative samples due to undetected Staphylococcus aureus infections were rare. The use of PCR technology may assist in rapid mastitis diagnosis, however, accurate interpretation of PCR results in the absence of bacterial culture remains problematic.
Asunto(s)
Mastitis Bovina/microbiología , Leche/microbiología , Reacción en Cadena en Tiempo Real de la Polimerasa/veterinaria , Animales , Bacterias/aislamiento & purificación , Técnicas Bacteriológicas/métodos , Técnicas Bacteriológicas/normas , Técnicas Bacteriológicas/veterinaria , Bovinos , Recuento de Colonia Microbiana/métodos , Recuento de Colonia Microbiana/veterinaria , Femenino , Mastitis Bovina/diagnóstico , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Reacción en Cadena en Tiempo Real de la Polimerasa/normas , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Staphylococcus aureus/aislamiento & purificación , Factores de TiempoRESUMEN
Effective mastitis control requires knowledge of the predominant pathogen challenges on the farm. In order to quantify this challenge, the aetiological agents associated with clinical mastitis in 30 milk-recording dairy herds in Ireland over a complete lactation were investigated. Standard bacteriology was performed on 630 pretreatment quarter milk samples, of which 56 per cent were culture-positive, 42 per cent culture-negative and 2 per cent contaminated. Two micro-organisms were isolated from almost 5 per cent of the culture-positive samples. The bacteria isolated were Staphylococcus aureus (23 per cent), Streptococcus uberis (17 per cent), Escherichia coli (9 per cent), Streptococcus species (6 per cent), coagulase-negative Staphylococci (4 per cent) and other species (1 per cent). A wide variety of bacterial species were associated with clinical mastitis, with S aureus the most prevalent pathogen overall, followed by S uberis. However, the bacterial challenges varied widely from farm to farm. In comparison with previous reports, in the present study, the contagious pathogens S aureus and Streptococcus agalactiae were less commonly associated with clinical mastitis, whereas, the environmental pathogens S uberis and E coli were found more commonly associated with clinical mastitis. While S aureus remains the pathogen most commonly associated with intramammary infection in these herds, environmental pathogens, such as S uberis and E coli also present a considerable challenge.
Asunto(s)
Mastitis Bovina/microbiología , Leche/microbiología , Infecciones Estafilocócicas/veterinaria , Infecciones Estreptocócicas/veterinaria , Animales , Bovinos , Industria Lechera , Escherichia coli/aislamiento & purificación , Escherichia coli/patogenicidad , Femenino , Irlanda , Mastitis Bovina/epidemiología , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/aislamiento & purificación , Staphylococcus aureus/patogenicidad , Infecciones Estreptocócicas/epidemiología , Infecciones Estreptocócicas/microbiología , Streptococcus/aislamiento & purificación , Streptococcus/patogenicidadRESUMEN
Genes whose products function in a common biological process are often co-regulated. When regulation occurs at the transcriptional level, co-expressed genes can be detected globally by expression arrays or by sequencing non-normalized cDNA libraries. We examined bovine gene expression in 27 tissues using non-normalized cDNA library sequencing. Contigs were generated from expressed sequence tags whose sequences overlapped. Contigs containing a minimum of five expressed sequence tags were ordered via a hierarchical clustering process, where the distance between the contigs represents their expression pattern similarity across tissues. Gene ontology terms associated with the genes in each cluster showed that co-clustered genes encoded proteins involved in a common biological process. This process can be used to annotate genes of unknown function in the cluster. Gene expression was compared between bovine and human tissues; there were significant correlations between species for each tissue, with the exception of thyroid and placenta. Tissues were also clustered based on the genes they express; tissues with similar physiological functions clustered closely. Based on this information, we generated the first preliminary gene atlas of the bovine genome. Genes with similar expression patterns were clustered, and genes with a common function co-clustered. This method can be used to annotate genes of unknown function in the bovine genome.
Asunto(s)
Bovinos/genética , Regulación de la Expresión Génica , Animales , Análisis por Conglomerados , Mapeo Contig , Etiquetas de Secuencia Expresada , Perfilación de la Expresión Génica , Biblioteca de Genes , Humanos , Filogenia , Proteínas Ribosómicas/genéticaRESUMEN
Gene expression was compared between resistant and susceptible Perendale lambs that had either never been exposed to gastrointestinal nematode challenge (had a naïve immune system with respect to parasites) or had been naturally challenged on pasture with nematodes. Only a small number of genes were differentially expressed between the naive resistant and susceptible animals, but many genes were differentially expressed between the resistant and susceptible challenged animals. The differentially expressed genes were involved in a variety of biological processes, most notably the immune response, the stress response and gene regulation via chromatin remodelling. The transcriptional profiling experiments also detected gene expression differences in the Ovar-DQA1 gene between resistant and susceptible challenged animals. A null allele of this gene was demonstrated to be associated with susceptibility to gastrointestinal parasites in some, but not all populations. This allele is not thought to be causal for susceptibility.
Asunto(s)
Perfilación de la Expresión Génica , Intestinos/parasitología , Transcripción Genética , Animales , Secuencia de Bases , Cartilla de ADN , Femenino , Masculino , OvinosRESUMEN
The DNA sequence of the gyr genes from Salmonella enterica serovar Typhimurium revealed strong similarity between gyrB and its counterpart in Escherichia coli. However, the gyrA gene showed similarity to the E. coli homologue only downstream from the Pribnow box of the promoter, with the sequence upstream diverging markedly. Since this region encompasses the binding sites for the Fis DNA binding protein in E. coli, we investigated the possibility that the gyrA genes in the two species might differ in their responses to this regulatory protein. Fis was found to act as a transcriptional repressor of both gyr genes in S. enterica. In electrophoretic mobility shift assays, Fis was found to bind to both the gyrA and gyrB promoters of S. enterica, despite the strong divergence from the E. coli sequence on the part of the former. The binding sites were mapped by DNase I protection assays, and the results are consistent with conservation of the mechanism of Fis-mediated repression between the two bacterial species.
Asunto(s)
Girasa de ADN/genética , Factor Proteico para Inverción de Estimulación/genética , Salmonella typhimurium/genética , Secuencia de Bases , Sitios de Unión , Huella de ADN , Girasa de ADN/aislamiento & purificación , Girasa de ADN/metabolismo , Cartilla de ADN , Desoxirribonucleasa I , Factor Proteico para Inverción de Estimulación/metabolismo , Regulación Bacteriana de la Expresión Génica , Regulación Enzimológica de la Expresión Génica , Cinética , Datos de Secuencia Molecular , Regiones Promotoras Genéticas/genética , Salmonella typhimurium/crecimiento & desarrolloRESUMEN
The relationship between environment and mutation is complex [1]. Claims of Lamarkian mutation [2] have proved unfounded [3-5]; it is apparent, however, that the external environment can influence the generation of heritable variation, through either direct effects on DNA sequence [6] or DNA maintenance and copying mechanisms [7-10], or as a consequence of evolutionary processes [11-16]. The spectrum of mutational events subject to environmental influence is unknown [6] and precisely how environmental signals modulate mutation is unclear. Evidence from bacteria suggests that a transient recombination-dependent hypermutational state can be induced by starvation [5]. It is also apparent that changes in the mutability of specific loci can be influenced by alterations in DNA topology [10,17]. Here we describe a remarkable instance of adaptive evolution in Salmonella which is caused by a mutation that occurs in intermediate-strength osmotic environments. We show that the mutation is not 'directed' and describe its genetic basis. We also present compelling evidence in support of the hypothesis that the mutational event is constrained by signals transmitted from the external environment via changes in the activity of DNA gyrase.