Mixtures of turkey herpesvirus (HVT) and Rispens poultry vaccines have been used worldwide for over 20 yr, mainly for vaccination of future layers and breeders. With increasing virulence of Marek's disease (MD) virus strains, vaccination strategies are evolving toward the use of vaccines combining HVT and Rispens. A single vaccination either in ovo or at 1 day of age with the HVT + infectious bursal disease (IBD) vector vaccine is efficient against IBD. However, with vaccination programs that include a hatchery administration of the HVT + IBD vaccine, additional protection against very virulent and very virulent-plus MD viruses is needed, especially for layers and breeders. This study looked at the combination of four commercially available Rispens vaccines with the HVT + IBD vector vaccine injected at 1 day of age. MD challenge tests that were superior to 90% in relative score in all the groups vaccinated with both vaccines showed that the mixture of HVT + IBD and Rispens vaccines had no effect on clinical protection against MD, and IBD challenge tests showed that the mixture of HVT + IBD and Rispens vaccines had no effect on clinical protection against IBD, which was equal to 100% protection in all the groups vaccinated with both vaccines. 相似文献
DNA amplification techniques offer considerable promise for the identification of Mycoplasma mycoides cluster members. They avoid antigenic cross-reactivity and variability that hamper serological methods. Many sets of primers, specific of these different members and of Mycoplasma putrefaciens, have been proposed. To assess the reliability of some of these PCR tests in routine laboratory diagnostic use, 230 field strains supposed to belong to this group were simultaneously identified by PCR and an antigenic method. The results were well correlated to antigenic identification for M. putrefaciens, but PCR failed to identify respectively 74% and 52% of M. mycoides subsp. mycoides Large Colony type and M. capricolum subsp. capricolum strains. Any identification of M. mycoides subsp. mycoides Small Colony type must be confirmed by two different tests. Difficulties in defining the M. species bovine serogroup 7 were also encountered with both the PCR and immunological methods. The occurrence of putative variable antigen(s) on the mycoplasma surface may explain part of the identification difficulties encountered with the immunological methods. 相似文献
Seven hysterectomy derived piglets were repeatedly challenged with Mycoplasma hyoneumoniae during the first week of life. Samples of trachea, bronchi and lung tissue collected 2–11 weeks post-inoculation (p.i.) were examined using light and electron microscopy. Autoradiography was used to study in more detail the site of M. hyopneumoniae multiplication. Gross lesions were observed in lung tissue and were characterized by hyperplasia of the epithelium and an increased mononuclear cell accumulation in perivascular and peribronchiolar areas. Mild lesions of the trachea and the bronchi, including epithelial hyperplasia and infiltration of the lamina propria by inflammatory cells, were noted.
Electron microscopy showed that, 2–6 weeks p.i., changes in the mid-trachea and bronchi surface consisted of the loss of cilia. Mycoplasmas covered tufts of cilia remaining on the epithelial cell surface. Scanning and transmission electron micrographs showed that they were predominantly found closely associated with the top of cilia. No specialized terminal structure could be seen and no mycoplasma cells were identified lying free in the lumen nor in close contact with the plasma membrane of cells of microvilli. Some fine fibrils radiating from one mycoplasma to another or to cilia were seen at higher magnification by scanning electron microscopy. Six to eleven weeks p.i., a disrupted epithelial surface lacking cilia was observed. Cells were desquamated and shed into the lumen with cellular remains containing droplets of mucus.
Autoradiography revealed that label corresponded to the observed mycoplasma distribution. At the top of cilia, a high density of labeling was visible in the zone of high mycoplasma concentration. Therefore, incorporation of the label in the mycoplasma is proof or their multiplication in the trachea.
The intimate association between the mycoplasma and cilia may be an important factor in the pathogenesis of the disease caused by M. hyopneumoniae (swine enzootic pneumonia). 相似文献
The biochemistry of intermuscular variation in tenderness is not fully understood. To investigate the role of the calpains in this process we performed two experiments using bovine and ovine species. In the bovine experiment, two distinct muscles, longissimus thoracis et lumborum (LT) and psoas major (PM), were used. In the ovine experiment, four muscles, LT, PM, semimembranosus (SM), and semitendinosus (ST), were used. Muscles were sampled at death for the determination of the steady-state mRNA level of calpains and calpastatin and the activities of calpain 1, 2, and calpastatin. Muscles were also sampled to determine the temporal changes in pH, tenderness, and the activity of the ubiquitous calpain system during postmortem aging. The results of the relative rate of tenderization in both species was found to be related to muscle type; LT had the highest value in both species. Within species, the mRNA steady-state levels of calpain 1 and calpastatin were similar in various bovine and ovine muscles. Bovine calpain 2 mRNA level was significantly lower in the LT than in the PM. Ovine calpain 2 mRNA level was lower, but not significantly different, in the LT compared to the other muscles. The mRNA level of bovine calpain 3 was significantly higher in the LT muscle than in the PM. In the ovine, the mRNA level of calpain 3 was highest in the LT, followed by SM, PM, and ST. Results on the activity of the ubiquitous calpain system in various muscles at death were dependent on muscle type and species. Temporal changes in the activity of calpains and calpastatin during the first 24 h of postmortem aging were similar in the muscles studied: calpain 1 and calpastatin declined significantly and calpain 2 remained relatively unchanged. The temporal changes in muscle pH in both experiments indicated that the extent and rate of pH decline during aging was related to muscle type. Correlation analysis between the relative rate of tenderization and mRNA expression of calpains revealed a strong relationship with calpain 3 in both species. 相似文献
1. The aim of this study was to examine the effect of sex and genotype on carcase composition and nutritional and sensory characteristics of chicken meat. The “Géline de Touraine” (GT) characterised by high carcase fatness was compared with an experimental crossbreed (EC) and “Label rouge” (LR) genotype.
2. Females compared with males, and GT chickens compared with LR and EC chickens were characterised by increased carcase fatness and an increased lipid level in thigh meat.
3. In both breast and thigh meat, the percentage of monounsaturated fatty acids was increased and the percentage of polyunsaturated fatty acids was decreased. However, these effects did not affect sensory characteristics of meat particularly those of roasted breast fillets containing very low lipid level by comparison with thigh meat.
4. Finally, in our study, high carcase fatness was related to high intermuscular fatness affecting the nutritional characteristics of meat but not its sensory attributes. 相似文献