Effects of immunization against a DNA vaccine encoding somatostatin gene (pGM-CSF/SS) by attenuated Salmonella typhimurium on growth, reproduction and lactation in female mice

A novel somatostatin (SS) DNA vaccine (pGM-CSF/SS), delivered orally by attenuated Salmonella typhimurium (CSO22), was used to immunize female mice at 5, 7, and 11 wk of age; the objective was to investigate the humoral immune response and effects of this vaccine on growth, reproduction and lactation. The pGM-CSF/SS induced SS-specific antibodies, which peaked (3.69 ± 0.89; mean ± S.D) 4 wk after the first booster immunization. Compared with a saline-treated control group, body weight gain of a pGM-CSF/SS immunized group increased 30.3% (23.88 vs. 18.32 g, P < 0.05) during the growth period (from 2 wk after primary immunization to 4 wk after the first booster immunization). Immunized mice had higher plasma estradiol concentrations (84.10 ± 2.16 vs. 81.45 ± 2.12 pg/ml, P < 0.05) and a shorter estrous cycle (4.06 ± 0.75 vs. 5.33 ± 0.49 d, P < 0.05), but serum progesterone concentrations were not significantly affected. Since offspring produced by immunized mice gained weight faster (P < 0.05) in the first 2 wk of life (4.27 ± 0.62 and 7.81 ± 1.30 g in Weeks 1 and 2, respectively vs. 3.70 ± 0.23 and 7.14 ± 0.48 g), we inferred that pGM-CSF/SS could have a direct or indirect role in regulating lactation in mice. In conclusion, GM-CSF and CSO22 served as adjuvant and attenuated live vector, respectively, with efficient oral delivery of an SS DNA vaccine which successfully induced a humoral immune response and enhanced rate of weight gain. Furthermore, the DNA vaccine pGM-CSF/SS affected plasma estradiol concentrations and the estrous cycle, and seemed to enhance lactation performance of female mice.     

Effect of recombinant growth hormone on expression of growth hormone receptor,insulin-like growth factor mRNA and serum level of leptin in growing pigs

Sixteen Large White × Landrace castrated male pigs were allotted into treatment and control group. The treatment group was injected intramuscularly with recombinant porcine growth hormone (rpGH, 4 mg d⁻¹) and the control group with vehicle for 28 days. Animals were slaughtered 4 h after final injection for liver, longissimus dorsi (LD) muscle and blood sampling. Serum concentration of insulin-like growth factor 1 (IGF-I) and leptin were determined by RIA. The total RNA was extracted from tissues to measure the abundance of growth hormone receptor (GHR), IGF-I mRNA by RT-PCR with 18S rRNA internal standard. Results showed that rpGH enhanced the average daily weight gain by 26.1% (P < 0.05), the serum IGF-I concentration by 70.94% (P < 0.01), decreased serum leptin by 34.8% (P < 0.01). The relative abundance of GHR and IGF-I mRNA in liver were increased by 24.45% (P < 0.05) and 45.30% (P < 0.01), respectively, but no difference of GHR (P > 0.05) and IGF-I mRNA (P > 0.05) in LD between GH treated and control group was found. These results suggest that rpGH can up-regulate hepatic GHR and IGF-I gene expression and improve animal growth. However the effect of rpGH on GHR and IGF-I gene expression are tissue-specific.     

Immunological Adjuvant Effect of a Water‐Soluble Polysaccharide,CPP, from the Roots of Codonopsis pilosula on the Immune Responses to Ovalbumin in Mice

In this study, one water‐soluble polysaccharide, CPP, was purified from the root of Codonopsis pilosula. The immunomodulatory effect and the adjuvant potential of CPP on the cellular and humoral immune response of ICR mice against ovalbumin (OVA) were investigated. CPP was shown not to be lethal in vivo for mice in doses ranging from 0.5 to 4 mg. ICR Mice were immunized subcutaneously with 0.1 mg of OVA alone or with 0.1 mg of OVA dissolved in saline‐containing aluminum hydroxide gel (Alum) (0.2 mg), QuilA (0.01 and 0.02 mg) or CPP (0.5, 1 or 2 mg) on days 1 and 15. Two weeks later (day 28), concanavalin A (ConA)‐, lipopolysaccharide (LPS)‐, and OVA‐stimulated splenocyte proliferation, and OVA‐specific serum antibodies were measured. CPP significantly enhanced the ConA‐, LPS‐, or OVA‐induced splenocyte proliferation in the OVA‐immunized mice especially at a dose of 1 mg (P<0.05 or P<0.01). The OVA‐specific IgG, IgG1, and IgG2b antibody levels in serum were also significantly enhanced by CPP compared with OVA control group (P<0.05 or P<0.01). The results suggest that CPP could be a safe efficacious adjuvant for use in vaccines against both pathogens and cancer.     

含分子内佐剂的SARS-CoV-2 RBD域重组蛋白制备及免疫效果评价北大核心CSCD

制备含破伤风毒素肽(tetanus toxin,TT)、促吞噬肽(tuftsin)和新型冠状病毒刺突蛋白(spike,S蛋白)受体结合域(receptor-binding domain,RBD)的融合蛋白,探讨分子内佐剂对RBD蛋白体液免疫和细胞免疫效果的影响。将破伤风毒素肽、促吞噬肽与S蛋白RBD区域通过柔性多肽串联,密码子优化后构建重组载体,原核表达纯化制备重组S-TT-tuftsin蛋白,与铝佐剂混合后免疫BALB/c小鼠,对其体液及细胞免疫效果进行评价。重组S-TT-tuftsin蛋白以包涵体形式表达,离子交换层析纯化后采用梯度透析进行复性,复性蛋白经Dot blotting鉴定,可与新冠亚单位疫苗(安徽智飞公司)免疫后人血清发生反应。小鼠免疫实验结果表明,免疫35 d时抗体水平到达平台期,含分子内佐剂重组蛋白(铝佐剂)免疫小鼠后血清ELISA抗体效价高达1︰66240,显著高于S-RBD蛋白(铝佐剂)免疫小鼠抗体效价(P<0.05)。同时,含分子内佐剂重组蛋白刺激小鼠产生更强的淋巴细胞增殖能力,刺激指数可达4.71±0.15,相较于S-RBD蛋白的刺激指数1.83±0.09具有显著性差异(P<0.0001)。分子内佐剂破伤风毒素肽和促吞噬肽可显著增强新冠S蛋白RBD域的体液免疫和细胞免疫效果,可为新冠亚单位疫苗和其他病毒亚单位疫苗的研制提供理论基础和参考。     

Macrophages largely contribute to heterologous anti‐Propionibacterium acnes antibody‐mediated protection from Actinobacillus pleuropneumoniae infection in mice

Actinobacillus pleuropneumoniae is the causative agent of acute and chronic pleuropneumonia. Propionibacterium acnes is a facultative anaerobic gram‐positive corynebacterium. We have previously found that anti‐P. acnes antibodies can prevent A. pleuropneumoniae infections in mice. To investigate the role of macrophages in this process, affinity‐purified anti‐P. acnes IgG and anti‐A. pleuropneumoniae IgG were used in opsonophagocytosis assays. Additionally, the efficacy of passive immunization with P. acnes serum against A. pleuropneumoniae was tested in macrophage‐depleted mice. It was found that anti‐P. acnes IgG had an effect similar to that of anti‐A. pleuropneumoniae IgG (P > 0.05), which significantly promotes phagocytosis of A. pleuropneumoniae by macrophages (P < 0.01). It was also demonstrated that, after passive immunization with anti‐P. acnes serum, macrophage‐replete mice had the highest survival rate (90%), whereas the survival rate of macrophage‐depleted mice was only 40% (P < 0.05). However, macrophage‐depleted mice that had been passively immunized with naïve serum had the lowest survival rate (20%), this rate being lower than that of macrophage‐replete mice that had been passively immunized with naïve serum. Overall, anti‐P. acnes antibodies did not prevent A. pleuropneumoniae infection under conditions of macrophage depletion (P > 0.05). Furthermore, in mice that had been passively immunized with anti‐P. acnes serum, macrophage depletion resulted in a greater A. pleuropneumoniae burden and more severe pathological features of pneumonia in lung tissues than occurred in macrophage‐replete mice. It was concluded that macrophages are essential for the process by which anti‐P. acnes antibody prevents A. pleuropneumoniae infection in mice.     

Effect of immunization with a recombinant cholera toxin B subunit/somatostatin fusion protein on immune response and growth hormone levels in mice

Somatostatin (SS) is a hormone that inhibits growth hormone secretion. Cholera toxin B subunit (CTB) is a widely used adjuvant to improve the immunogenicity of co-administrated antigen. To block the growth hormone-inhibiting effect of SS, a fusion gene of CTB and SS was constructed and expressed in Escherichia coli. The purified CTB/SS fusion protein polymerized into a biologically active pentamer required for CTB binding to the GM1 ganglioside receptor. Immunization with the CTB/SS protein induced specific immunity against CTB and SS in mice. The serum growth hormone of the CTB/SS-treated mice increased by 29?% (P?<?0.05) compared with the control. The results indicated that the CTB/SS fusion protein was effective in inducing immune response against SS as well as elevating the growth hormone level.     

Effect of High Dietary Copper on Somatostatin and Growth Hormone-Releasing Hormone Levels in the Hypothalami of Growing Pigs

This experiment was conducted to examine the effect of dietary copper supplementation on somatostatin (SS) and growth hormone-releasing hormone (GHRH) mRNA expression levels in the hypothalami of growing pigs. A total of 45 crossbred pigs were randomly assigned to three groups of 15 pigs each; five replicates of three animals comprised each group. Pigs were allocated to diets that contained 5 mg/kg copper (control), 125 mg/kg copper sulfate, or 125 mg/kg copper methionine. At the end of the experiment, five pigs were selected at random from each group and slaughtered, and hypothalami were collected for determination of SS and GHRH mRNA expression levels. The results showed that the SS expression levels were lower and the GHRH levels were higher in pigs fed the diets with 125 mg/kg copper methionine (P < 0.05) and 125 mg/kg copper sulfate (P < 0.05), respectively, than in pigs fed the diet with 5 mg/kg copper. Furthermore, the relationship between SS mRNA and GHRH mRNA abundance had a significantly negative correlation (P < 0.05). The data indicated that high dietary copper could enhance GHRH mRNA expression levels and suppress SS mRNA expression levels in the hypothalami of pigs. High lever dietary copper (125 mg/kg copper sulfate or 125 mg/kg copper methionine) increased pigs’ growth performance and feed efficiency but had no significant effect on daily feed intake; 125 mg/kg copper sulfate or 125 mg/kg copper methionine at the same lever had no difference on growth promoting in pigs.     

Platycodin D2 Improves Specific Cellular and Humoral Responses to Hepatitis B Surface Antigen in Mice

Platycodin D2 ( 1 ), a less hemolytic saponin from the root of Platycodon grandiflorum than platycodin D ( 2 ), was evaluated for the potential to enhance specific cellular and humoral immune responses to hepatitis B surface antigen (HBsAg) in mice. It significantly increased the concanavalin A (Con A)‐, lipopolysaccharide (LPS)‐, and HBsAg‐induced splenocyte proliferation in HBsAg‐immunized mice (P<0.05, P<0.01, and P<0.001, resp.). HBsAg‐specific IgG, IgG1, IgG2a, and IgG2b antibody titers in the serum were also markedly enhanced by 1 compared to the HBsAg control group (P<0.01 or P<0.001). Moreover, 1 significantly promoted the production of Th1 (IL‐2 and IFN‐γ) and Th2 (IL‐4 and IL‐10) cytokines from splenocytes in the HBsAg‐immunized mice (P<0.001). The adjuvant potential of 1 on splenocyte proliferation, serum HBsAg‐specific IgG2a and IgG2b antibody response, as well as Th1‐cytokine secretion from splenocytes in the HBsAg‐immunized mice was higher than that of Alum. The results suggest that 1 could improve both cellular and humoral immune responses to HBsAg in mice. Hence, 1 might be a promising adjuvant for hepatitis B vaccine with dual Th1‐ and Th2‐potentiating activity.     

Safety assessment of leaf curl virus resistant tomato developed using viral derived sequences

Genetic engineering of food crops has significantly influenced the agricultural productivity over the past two decades. It has proved a valuable tool, offering crops with higher yields, improved nutritional quality, resistance against pesticides, herbicides and tolerance against abiotic stresses. However, the safety assessment of genetically engineered (GE) crops is prerequisite before introduction into human food chain. The present study was aimed to assess the toxicity and allergenicity of leaf curl virus resistant GE tomato compared to its wild-type species. Balb/c mice fed with genetically engineered or wild-type tomato did not show significant differences in growth, body weight (P > 0.05) and food consumption when compared with control mice. Values for serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase, urea and cholesterol were comparable in GE and wild-type tomato fed mice. Mice immunized with GE or wild-type tomato extract showed low IgE response. Lung histology of ovalbumin fed mice showed bronchoconstriction with eosinophilic infiltration whereas GE or wild-type tomato showed no cellular infiltration with normal airways. Genetically engineered and wild-type tomato sensitized mice demonstrated similar IL-4 release in splenic cell culture supernatant. GE and wild tomato extract on ELISA showed comparable IgE binding (P > 0.05) with food allergic patients’ sera. In conclusion, genetically engineered tomato showed no toxicity in mice and allergenicity is similar to the wild-type tomato.     

Dietary rapamycin supplementation reverses age‐related vascular dysfunction and oxidative stress,while modulating nutrient‐sensing,cell cycle,and senescence pathways

Inhibition of mammalian target of rapamycin, mTOR, extends lifespan and reduces age‐related disease. It is not known what role mTOR plays in the arterial aging phenotype or if mTOR inhibition by dietary rapamycin ameliorates age‐related arterial dysfunction. To explore this, young (3.8 ± 0.6 months) and old (30.3 ± 0.2 months) male B6D2F1 mice were fed a rapamycin supplemented or control diet for 6–8 weeks. Although there were few other notable changes in animal characteristics after rapamycin treatment, we found that glucose tolerance improved in old mice, but was impaired in young mice, after rapamycin supplementation (both P < 0.05). Aging increased mTOR activation in arteries evidenced by elevated S6K phosphorylation (P < 0.01), and this was reversed after rapamycin treatment in old mice (P < 0.05). Aging was also associated with impaired endothelium‐dependent dilation (EDD) in the carotid artery (P < 0.05). Rapamycin improved EDD in old mice (P < 0.05). Superoxide production and NADPH oxidase expression were higher in arteries from old compared to young mice (P < 0.05), and rapamycin normalized these (P < 0.05) to levels not different from young mice. Scavenging superoxide improved carotid artery EDD in untreated (P < 0.05), but not rapamycin‐treated, old mice. While aging increased large artery stiffness evidenced by increased aortic pulse‐wave velocity (PWV) (P < 0.01), rapamycin treatment reduced aortic PWV (P < 0.05) and collagen content (P < 0.05) in old mice. Aortic adenosine monophosphate‐activated protein kinase (AMPK) phosphorylation and expression of the cell cycle‐related proteins PTEN and p27kip were increased with rapamycin treatment in old mice (all P < 0.05). Lastly, aging resulted in augmentation of the arterial senescence marker, p19 (P < 0.05), and this was ameliorated by rapamycin treatment (P < 0.05). These results demonstrate beneficial effects of rapamycin treatment on arterial function in old mice and suggest these improvements are associated with reduced oxidative stress, AMPK activation and increased expression of proteins involved in the control of the cell cycle.     

Secretory expression of K88 (F4) fimbrial adhesin FaeG by recombinant <Emphasis Type="Italic">Lactococcus lactis</Emphasis> for oral vaccination and its protective immune response in mice

K88 (F4) fimbrial adhesin, FaeG, was expressed extracellularly in Lactococcus lactis using a nisin-controlled gene expression system. The antibody response and protective efficacy of the recombinant bacteria (L. lactis [spNZ8048-faeG]) against live enterotoxigenic E. coli (ETEC) C₈₃₅₄₉ challenge were evaluated in ICR mice. Mice vaccinated with L. lactis [spNZ8048-faeG] had a significantly increased antigen-specific IgG level in the serum and decreased mortality rate (P < 0.05) compared with the control. This indicates that oral immunization of L. lactis [spNZ8048-faeG] can induce an immune-response protection upon challenge with live ETEC in ICR mice. An erratum to this article can be found at     

Anticonvulsant and Antioxidant Effects of Cyano-carvone and Its Action on Acetylcholinesterase Activity in Mice Hippocampus

The anticonvulsant effect of cyano-carvone, a monoterpene monocyclic, was investigated in epilepsy model induced by pilocarpine. Cyano-carvone at doses of 25, 50 or 75 mg/kg promoted a reduction of 16.7, 33 and 66.7%, respectively, against pilocarpine-induced seizures, and it was efficacious in increasing both the latency to first seizures and the survival percentage, resulting in 33.3, 67 and 91.7% of protection against death induced by seizures, respectively (P < 0.05). The reference drug atropine (25 mg/kg) also produced a significant protection (100%). Its monoterpene, at 25, 50 and 75 mg/kg, was also capable to increase the latency for installation of status epilepticus induced by pilocarpine, and presented a significant protection against lipid peroxidation and nitrite formation in mice hippocampus (P < 0.05). In addition, it was observed that the cyano-carvone pretreatment increased the acetylcholinesterase activity in mice hippocampus after pilocarpine-induced seizures. The present results clearly indicate the anticonvulsant ability of cyano-carvone, which can be, at least in part, explained by the increased activity of the acetylcholinesterase enzyme. Our data suggest that the action mechanism can also be due to a direct activation of the antioxidant enzymes that could be associated with a reduction observed in oxidative stress in mice hippocampus, probably involving an inhibition of free radical production.     

Cloning and differential expression of the growth hormone in Pampus argenteus

The growth hormone (GH) is a pluripotent hormone produced by the pituitary in vertebrates. It plays important roles in the growth, development, and metabolism of vertebrates.We cloned GH cDNA sequence of Pampus argenteus (GenBank: KT257176). Multi‐sequence analysis revealed P. argenteus GH cDNA contained four conservative cysteine residues positions (Cys⁶⁹, Cys¹⁷⁷, Cys¹⁹⁴, and Cys²⁰²) and shared more than 51.5% identity with homologues from other reported bony fish GHs, except that of Lepisosteus osseus. We used semi‐quantitative RT‐PCR and quantitative real‐time PCR to detect GH expression in 10 tissues and GH expression levels in the pituitary at six different growth stages, and also detected GH content in serum at different growth stages . qPCR showed that GH mRNA was detected in the liver, muscle, kidney, intestine, pituitary, olfactory bulb, stomach, heart, gill, and ovary. The highest level of P. argenteus GH mRNA was observed in the pituitary (P < 0.01, n = 3). At different growth stages, P. argenteus GH expression first increased, decreased, and increased again. GH gene expression levels and the variations of serum GH levels of P. argenteus were consistent with the growth rate and associated with the sexual maturity. In addition, in situ hybridization was used to locate the GH expression in pituitary. In situ hybridization showed that the GH‐positive cells were round, oval, or irregular and often gathered into groups or presented branches along the nerve fibers.     

Comparison of serum antibody responses and host protection against parasite Ichthyophthirius multifiliis between channel catfish and channel × blue hybrid catfish

There is limited information available on the immune protection of channel catfish Ictalurus punctatus × blue catfish I. furcatus (CB) hybrid against the fish parasite Ichthyophthirius multifiliis (Ich). The objective of this study was to compare serum antibody response and host protection between channel catfish and CB hybrid catfish using a cohabitation model. Channel catfish and CB hybrid catfish were immunized with live theronts by immersion or by IP injection at the dose of 10,000–20,000 theronts per fish in two trials. The fish were then challenged with theronts to compare serum antibody response and protection against the parasite between channel catfish and CB hybrid catfish. The immunized channel catfish and CB hybrid catfish showed a significantly higher (p < 0.05) serum anti-Ich antibody (titer > 1120) compared to non-immunized controls (titer = 0). After being challenged with live theronts, the immunized channel catfish and CB hybrid catfish had none or a low number of the parasites (<50 trophonts per fish) and showed a significantly higher (p < 0.05) survival (90–100%) than non-immunized controls (0%). Overall results indicated that there was no statistical (p > 0.05) difference on serum anti-Ich antibody, parasite infection and fish survival between immunized channel catfish and CB hybrid catfish.     

Expression fusion immunogen by live attenuated Escherichia coli against enterotoxins infection in mice

Previous epidemiological studies have shown that enterotoxins from enterotoxigenic Escherichia coli (ETEC) appear to be the most important causes of neonatal piglet and porcine post-weaning diarrhoea (PWD). Thus, it is necessary to develop an effective vaccine against ETEC infection. In the present study, the Kil cassette was inserted into the pseudogene yaiT by homologous recombination to create an attenuated E. coli double selection platform O142(yaiT-Kil). After that, PRPL-Kil was replaced with a fusion gene (LTA1-STa₁₃-STb-LTA2-LTB-STa₁₃-STb) to establish oral vaccines O142(yaiT::LTA1-STa₁₃-STb-LTA2-LTB-STa₁₃-STb) (ER-T). Subsequently, BALB/c mice were orally immunized with ER-T. Results showed that serum IgG and faecal sIgA responded against all ETEC enterotoxins and induced F41 antibody in BALB/c mice by orogastrically inoculation with recombinant E. coli ER-T. Moreover, the determination of cellular immune response demonstrated that the stimulation index (SI) was significantly higher in immunized mice than in control mice, and a clear trend in the helper T-cell (Th) response was Th2-cell (IL-4) exceed Th1-cell (IFN-γ).Our results indicated that recombinant E. coli ER-T provides effective protection against ETEC infection.     

Intranasally administered Lactobacillus gasseri TMC0356 protects mice from H1N1 influenza virus infection by stimulating respiratory immune responses

We conducted a study to evaluate the possibility that intranasal administration of a new probiotic strain Lactobacillus gasseri TMC0356 (TMC0356) may protect host animals from influenza virus (IFV) infection, which was indicated by enhanced respiratory immune responses in a mouse model. After 3 days of exposure to TMC0356, BALB/c mice were intranasally infected with IFVA/PR/8/34 (H1N1). Lung cells were isolated from the tested mice and evaluated for cytotoxicity against YAC-1 cells. After intranasal treatment with TMC0356, mice showed a lower morbidity and higher survival rate compared to control mice (P < 0.05). The cytotoxicity of lung cells isolated from mice after intranasal treatment against YAC-1 cells was statistically higher than that of lung cells isolated from control mice (P < 0.05). Intranasal administration of TMC0356 significantly increased mRNA expression of interleukin (IL)-1β, tumor necrosis factor, IL-10, and monocyte chemotactic protein-1 (P < 0.01). These results suggest that intranasal administration of TMC0356 may protect the host animal from IFV infection. They also indicate that TMC0356 can enhance respiratory cell-mediated immune responses of host animals characteristically with up-regulated activation of lung natural killer cells. Further studies will evaluate the possible role of the immune stimulatory effects of TMC0356 within the protective effects of this bacterium against IFV, as observed in the present study.     

Influence of Dietary Copper Methionine Concentrations on Growth Performance,Digestibility of Nutrients,Serum Lipid Profiles,and Immune Defenses in Broilers

A 42-day experiment was conducted to evaluate the influence of dietary copper (Cu) concentrations on growth performance, nutrient digestibility, and serum parameters in broilers aged from 1 to 42 days. Five hundred forty 1-day-old broilers were randomly assigned into 1 of the following 6 dietary treatments: (1) control (basal diet without supplemental Cu), (2) 15 mg/kg supplemental Cu (Cu15), (3) 30 mg/kg supplemental Cu (Cu30), (4) 60 mg/kg supplemental Cu (Cu60), (5) 120 mg/kg supplemental Cu (Cu120), and (6) 240 mg/kg supplemental Cu (Cu240), Cu as copper methionine. A 4-day metabolism trial was conducted during the last week of the experiment feeding. The results showed that dietary Cu supplementation increased the average daily gain and the average daily feed intake (P < 0.01). The feed gain ratio, however, was not affected by dietary Cu (P > 0.10). Additionally, dietary Cu supplementation increased the digestibility of fat and energy (P < 0.05). The concentration of serum cholesterol, triglycerides, and high-density lipoprotein cholesterol decreased with dietary Cu supplementation (P < 0.05). The activities of serum Cu-Zn superoxide dismutase (P < 0.05), glutathione peroxidase (P < 0.05), and ceruloplasmin (P = 0.09), on the contrary, were increased by Cu addition. For immune indexes, dietary Cu supplementation increased serum IgA and IgM (P < 0.05). In addition, the activities of serum ALT increased with increasing dietary Cu supplementation (P < 0.05). In conclusion, our data suggest that Cu supplementation can increase fat digestibility and promote growth. Additionally, dietary Cu supplementation can reduce serum cholesterol and enhance antioxidant capacity in broilers.

     

The Effect of Dietary Selenium Source and Level on Hen Production and Egg Selenium Concentration

A 16-week experiment was conducted to compare effects of various levels of sodium selenite (SS) and Se-enriched yeast (SY), on the whole-egg Se content and hen’s productivity. One hundred Shaver 579 hens, 27 weeks old, were placed on one of five experimental treatments. Each treatment was replicated four times with five hens per cage. Treatments consisted of feeding a low Se diet without supplementation (basal diet) or basal diet with one of two levels of supplemented Se (0.4 or 0.8 mg/kg) supplied by SS or SY. All supplemented treatments had significantly higher whole-egg Se concentration from basal diet (P < 0.05). On the same supplemented level, hens fed on SY had higher egg Se content from hens feed on SS (P < 0.001). No effects of dietary treatments on egg weight, percentages of dirty and cracked egg, and feed intake and conversion of feed were observed throughout the trial (P < 0.05). In the first 8 weeks, there was no significant difference (P < 0.05) in hen-day egg production among treatments. From the ninth week on to the end of the trial, supplementation of SY to hen’s diet resulted in a higher egg production than SS (P < 0.01).     

Protective immunity of <Emphasis Type="Italic">E. coli</Emphasis>-synthesized NS1 protein of Japanese encephalitis virus

Immunogenicity and protective efficacy of recombinant Japanese encephalitis virus (JEV) NS1 proteins generated using DNA vaccines and recombinant viruses have been demonstrated to induce protection in mice against a challenge of JEV at a lethal dose. The West Nile virus NS1 region expressed in E. coli is recognized by these protective monoclonal antibodies and, in this study, we compare immunogenicity and protective immunity of the E. coli-synthesized NS1 protein with another protective immunogen, the envelope domain III (ED3). Pre-challenge, detectable titers of JEV-specific neutralizing antibody were detected in the immunized mice with E. coli-synthesized ED3 protein (PRNT50 = 1:28) and the attenuated JEV strain T1P1 (PRNT50 = 1:53), but neutralizing antibodies were undetectable in the immunized mice with E. coli-synthesized NS1 protein (PRNT50 < 1:10). However, the survival rate of the NS1-immunized mice against the JEV challenge was 87.5% (7/8), showing significantly higher levels of protection than the ED3-immunized mice, 62.5% (5/8) (P = 0.041). In addition, E. coli-synthesized NS1 protein induced a significant increase of anti-NS1 IgG1 antibodies, resulting in an ELISA titer of 100,1000 in the immunized sera before lethal JEV challenge. Surviving mice challenged with the virulent JEV strain Beijing-1 showed a ten-fold or greater rise in IgG1 and IgG2b titers of anti-NS1 antibodies, implying that the Th2 cell activation might be predominantly responsible for antibody responses and mice protection.