Browsing by Subject "immune response"
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Item Genomic Approaches to Study Innate Immune Response to Salmonella Enteritidis Infection in Chickens(2010-01-14) Chiang, Hsin-ISalmonella enterica serovar Enteritidis (SE) is one of the most common food-borne pathogens that cause human salmonellosis. Contamination of consumed poultry products continues to be a global threat to public health. Genetic resistance using genomic approach provides a promising solution to controlling SE infection in poultry. The mechanism of SE resistance in chickens remains elusive. Three different approaches, microarray techology, gene silencing, and computational gene analysis, have been utilized to study SE-induced transcriptional changes of host immune response in the chicken. A whole genome chicken 44K microarray was used to analyze the transcriptome of heterophils from SE-resistant (line A) and SE-susceptible chickens (line B) with/without in vitro SE stimulation. Many differentially expressed immune-related genes were found in the SE-infected to non-infected comparison, where more immune-related genes were down-regulated in line B than line A. These results suggested a similar Toll-like receptor (TLR) regulatory network might exist in heterophils of both lines, and provided strong candidates for further investigating SE resistance and susceptibility in chickens. In the gene silencing study, small interfering RNAs (siRNA) were used to specifically inhibit the expression of NFkB1 in the chicken HD11 macrophage cell line with SE challenge. Genes related to the NF-kB signaling pathway were selected to examine the effect of NFkB1 inhibition on TLR pathway. With 36% inhibition of NFkB1 expression, the results showed an increased expression of TLR4 and interleukin (IL)-6 following SE challenge and suggested a likely inhibitory regulation of NFkB1 on TLR signal pathway. Finally, two novel chicken C-type lectin-like receptors were identified and annotated to chicken CD69 and CD94/NKG2-like with multiple evidences generated by computational (in-silico) sequence analysis. Both genes located in a region on chicken chromosome 1 that is syntenic to mammalian Nature Killer Receptor Complex (NKC) region, which may have existed before the divergence between mammals and aves. While siRNA lays the foundation of using loss-of-function approach on testifying gene-gene interactions, in-silico analysis aids in gathering information of unknown genes of great interest. Both approaches provide great potential to use for down-stream analysis following microarray study.Item Selenium nutrition of Morone hybrids including dietary requirements, bioavailability, toxicity and effects on immune responses and disease resistance(Texas A&M University, 2006-08-16) Jaramillo, Francisco , JrAquacultural production of hybrid striped bass (HSB) Morone chrysops ?? M. saxatilis is highly vulnerable to losses from bacterial pathogens such as Streptococcus iniae. Therefore, research was conducted to evaluate various dietary factors that may enhance immunocompetence and disease resistance of HSB. In the first experiment, purified and practical diets were supplemented with β-glucan and selenium in a factorial arrangement and fed to juvenile HSB for 6 wk followed by a S. iniae challenge. Weight gain (WG) and feed efficiency (FE) were higher for fish fed either practical diets or purified diets supplemented with selenium, but not those supplemented with β-glucan. Survival after disease challenge for fish fed the selenium-supplemented practical and purified diets was 75% and 35%, respectively. Because selenium supplementation also improved WG and FE, and because selenium and vitamin E have complementary biochemical functions, a second experiment evaluated potential interactions by feeding purified diets with or without vitamin E or sodium selenite (Na2SeO3), singularly or in combination, for 12 wk. Dietary selenium significantly affected whole-body selenium concentration but there was no effect of dietary selenium, vitamin E or their interaction on WG, FE, survival or blood neutrophil oxidative radical production. Three additional 12-wk experiments were conducted to establish selenium essentiality, toxicity, tissue deposition, dietary requirements, bioavailability and nonspecific immune responses using purified diets with a basal selenium level of 0.11 mg/kg. In one experiment, diets had selenium concentrations of 1.19, 2.00, 5.17 and 21.23 mg/kg from Na2SeO3. Another experiment had selenium concentrations of 0.90, 1.26 and 2.55 mg/kg from seleno-DL-methionine. The third trial utilized selenium from Na2SeO3, seleno-DL-methionine and selenium yeast at approximately 0.15, 0.30 and 0.60 mg/kg diet. No overt selenium deficiency signs were observed in any of the three latter experiments, but based on selenium retention values, a minimum dietary requirement of approximately 0.1 mg/kg was estimated. Selenium toxicity was observed in fish fed the diet containing more than 20 mg/kg. Bioavailability of selenium sources was ranked as seleno-DL-methionine > selenium yeast > Na2SeO3.