Effects of access to feed, water, and a competitive exclusion product in the hatcher on some immune traits and gut development in broiler chickens

1. This study evaluated the effect of access to feed, water, and the competitive exclusion (CE) product Broilact((R)), administered in the hatcher, on broiler performance, caecal microbiota development, organ development, intestinal morphology, serum levels of IgY and vaccine-induced antibody responses.2. In total, 250 chicks were hatched in a HatchCare (TM) hatcher and divided into four groups, given access to feed, water and the CE product sprayed on the chicks (CEs); access to feed, water, and the CE product in water (CEw); access to feed and water (Cpos); or no access to feed and water (Cneg) in the hatcher.3. At the research facility, 10 chicks per hatching treatment were euthanised for organ measurements. The remaining 200 chicks were randomly distributed to 20 pens. On d 11, all birds were vaccinated against avian pneumovirus (APV). Three focal birds per pen were blood-sampled weekly for quantification of IgY and serum antibodies to APV. On d 11 and 32, two birds per replicate pen were euthanised for organ measurements and sample collection. Feed intake and body weight were recorded weekly.4. Delayed access to feed and water reduced weight gain and feed intake early in life. At the end of the study, no differences in body weight remained.5. There were some early effects on organs, with depressed intestinal development and higher relative gizzard weight for the Cneg group at placement. No treatment effects on the immune traits measured were detected.6. The relative abundance of seven bacterial genera differed between treatment groups at d 11 of age. The results suggested that chickens are capable of compensating for 40 h feed and water deprival post-hatch. Provision of Broilact((R)) did not have any persistent performance-enhancing properties, although different outcomes under rearing conditions closer to commercial production cannot be ruled out

Immune response of healthy horses to DNA constructs formulated with a cationic lipid transfection reagent

Background Deoxyribonucleic acid (DNA) vaccines are used for experimental immunotherapy of equine melanoma. The injection of complexed linear DNA encoding interleukin (IL)-12/IL-18 induced partial tumour remission in a clinical study including 27 grey horses. To date, the detailed mechanism of the anti-tumour effect of this treatment is unknown. Results In the present study, the clinical and cellular responses of 24 healthy horses were monitored over 72 h after simultaneous intradermal and intramuscular application of equine IL-12/IL-18 DNA (complexed with a transfection reagent) or comparative substances (transfection reagent only, nonsense DNA, nonsense DNA depleted of CG). Although the strongest effect was observed in horses treated with expressing DNA, horses in all groups treated with DNA showed systemic responses. In these horses treated with DNA, rectal temperatures were elevated after treatment and serum amyloid A increased. Total leukocyte and neutrophil counts increased, while lymphocyte numbers decreased. The secretion of tumour necrosis factor alpha (TNFα) and interferon gamma (IFNγ) from peripheral mononuclear blood cells ex vivo increased after treatments with DNA, while IL-10 secretion decreased. Horses treated with DNA had significantly higher myeloid cell numbers and chemokine (C-X-C motif) ligand (CXCL)-10 expression in skin samples at the intradermal injection sites compared to horses treated with transfection reagent only, suggesting an inflammatory response to DNA treatment. In horses treated with expressing DNA, however, local CXCL-10 expression was highest and immunohistochemistry revealed more intradermal IL-12-positive cells when compared to the other treatment groups. In contrast to non-grey horses, grey horses showed fewer effects of DNA treatments on blood lymphocyte counts, TNFα secretion and myeloid cell infiltration in the dermis. Conclusion Treatment with complexed linear DNA constructs induced an inflammatory response independent of the coding sequence and of CG motif content. Expressing IL-12/IL-18 DNA locally induces expression of the downstream mediator CXCL-10. The grey horses included appeared to display an attenuated immune response to DNA treatment, although grey horses bearing melanoma responded to this treatment with moderate tumour remission in a preceding study. Whether the different immunological reactivity compared to other horses may contributes to the melanoma susceptibility of grey horses remains to be elucidated

Influenza Infectious Dose May Explain the High Mortality of the Second and Third Wave of 1918–1919 Influenza Pandemic

BACKGROUND: It is widely accepted that the shift in case-fatality rate between waves during the 1918 influenza pandemic was due to a genetic change in the virus. In animal models, the infectious dose of influenza A virus was associated to the severity of disease which lead us to propose a new hypothesis. We propose that the increase in the case-fatality rate can be explained by the dynamics of disease and by a dose-dependent response mediated by the number of simultaneous contacts a susceptible person has with infectious ones. METHODS: We used a compartment model with seasonality, waning of immunity and a Holling type II function, to model simultaneous contacts between a susceptible person and infectious ones. In the model, infected persons having mild or severe illness depend both on the proportion of infectious persons in the population and on the level of simultaneous contacts between a susceptible and infectious persons. We further allowed for a high or low rate of waning immunity and volunteer isolation at different times of the epidemic. RESULTS: In all scenarios, case-fatality rate was low during the first wave (Spring) due to a decrease in the effective reproduction number. The case-fatality rate in the second wave (Autumn) depended on the ratio between the number of severe cases to the number of mild cases since, for each 1000 mild infections only 4 deaths occurred whereas for 1000 severe infections there were 20 deaths. A third wave (late Winter) was dependent on the rate for waning immunity or on the introduction of new susceptible persons in the community. If a group of persons became voluntarily isolated and returned to the community some days latter, new waves occurred. For a fixed number of infected persons the overall case-fatality rate decreased as the number of waves increased. This is explained by the lower proportion of infectious individuals in each wave that prevented an increase in the number of severe infections and thus of the case-fatality rate. CONCLUSION: The increase on the proportion of infectious persons as a proxy for the increase of the infectious dose a susceptible person is exposed, as the epidemic develops, can explain the shift in case-fatality rate between waves during the 1918 influenza pandemic.TD acknowledges the support of the Faculdade de Ciencias e Tecnologia through grant PPCDT/AMB/55701/2004. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript

Immunity Traits in Pigs: Substantial Genetic Variation and Limited Covariation

BACKGROUND: Increasing robustness via improvement of resistance to pathogens is a major selection objective in livestock breeding. As resistance traits are difficult or impossible to measure directly, potential indirect criteria are measures of immune traits (ITs). Our underlying hypothesis is that levels of ITs with no focus on specific pathogens define an individual's immunocompetence and thus predict response to pathogens in general. Since variation in ITs depends on genetic, environmental and probably epigenetic factors, our aim was to estimate the relative importance of genetics. In this report, we present a large genetic survey of innate and adaptive ITs in pig families bred in the same environment. METHODOLOGY/PRINCIPAL FINDINGS: Fifty four ITs were studied on 443 Large White pigs vaccinated against Mycoplasma hyopneumoniae and analyzed by combining a principal component analysis (PCA) and genetic parameter estimation. ITs include specific and non specific antibodies, seric inflammatory proteins, cell subsets by hemogram and flow cytometry, ex vivo production of cytokines (IFNα, TNFα, IL6, IL8, IL12, IFNγ, IL2, IL4, IL10), phagocytosis and lymphocyte proliferation. While six ITs had heritabilities that were weak or not significantly different from zero, 18 and 30 ITs had moderate (0.1<h2≤0.4) or high (h2>0.4) heritability values, respectively. Phenotypic and genetic correlations between ITs were weak except for a few traits that mostly include cell subsets. PCA revealed no cluster of innate or adaptive ITs. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that variation in many innate and adaptive ITs is genetically controlled in swine, as already reported for a smaller number of traits by other laboratories. A limited redundancy of the traits was also observed confirming the high degree of complementarity between innate and adaptive ITs. Our data provide a genetic framework for choosing ITs to be included as selection criteria in multitrait selection programmes that aim to improve both production and health traits

Distinct Peripheral Blood RNA Responses to Salmonella in Pigs Differing in Salmonella Shedding Levels: Intersection of IFNG, TLR and miRNA Pathways

Transcriptomic analysis of the response to bacterial pathogens has been reported for several species, yet few studies have investigated the transcriptional differences in whole blood in subjects that differ in their disease response phenotypes. Salmonella species infect many vertebrate species, and pigs colonized with Salmonella enterica serovar Typhimurium (ST) are usually asymptomatic, making detection of these Salmonella-carrier pigs difficult. The variable fecal shedding of Salmonella is an important cause of foodborne illness and zoonotic disease. To investigate gene pathways and biomarkers associated with the variance in Salmonella shedding following experimental inoculation, we initiated the first analysis of the whole blood transcriptional response induced by Salmonella. A population of pigs (n = 40) was inoculated with ST and peripheral blood and fecal Salmonella counts were collected between 2 and 20 days post-inoculation (dpi). Two groups of pigs with either low shedding (LS) or persistent shedding (PS) phenotypes were identified. Global transcriptional changes in response to ST inoculation were identified by Affymetrix Genechip® analysis of peripheral blood RNA at day 0 and 2 dpi. ST inoculation triggered substantial gene expression changes in the pigs and there was differential expression of many genes between LS and PS pigs. Analysis of the differential profiles of gene expression within and between PS and LS phenotypic classes identified distinct regulatory pathways mediated by IFN-γ, TNF, NF-κB, or one of several miRNAs. We confirmed the activation of two regulatory factors, SPI1 and CEBPB, and demonstrated that expression of miR-155 was decreased specifically in the PS animals. These data provide insight into specific pathways associated with extremes in Salmonella fecal shedding that can be targeted for further exploration on why some animals develop a carrier state. This knowledge can also be used to develop rational manipulations of genetics, pharmaceuticals, nutrition or husbandry methods to decrease Salmonella colonization, shedding and spread

Visualisation and characterisation of mononuclear phagocytes in the chicken respiratory tract using CSF1R-transgenic chickens

Additional file 2. Location of B cells, T cells and follicular dendritic cells (FDC) in the lung of MacReporter chickens. The BALT region of 5 to 7 week old non-vaccination animals were analysed for B, T and FCD cells. Isotype controls were used to standardise the microscope and examine aspecific binding before acquiring images (A-B). The GC of MacReporter animals are tightly packed with Bu1-CSF1R-eGFP+ FDC cells and Bu1+CSF1R-eGFP- B cells (C) with few Bu1+ B cells found in the parabronchi (F). CD3+ T cells are disperse within and outside the GC (D) and parabronchi (G). CSF1R-eGFP+ FDC cells express Fc receptors and trap immunoglobulin by expressing IgY (E) and CSF1R-eGFP+ IgY+ FDC are rarely detected out with the GC, BALT region of the lung. GC are indicated by white dashed lines

Veterinary immunology: opportunities and challenges.

The 6th International Veterinary Immunology Symposium (6IVIS) was held in Uppsala, Sweden from 15-20 July 2001