A Serum Metabolic Profiling Analysis During the Formation of Fatty Liver in Landes Geese via GC-TOF/MS.

During the process of fatty liver production by overfeeding, the levels of endogenous metabolites in the serum of geese would change dramatically. This study investigated the effects of overfeeding on serum metabolism of Landes geese and the underlying mechanisms using a metabolomics approach. Sixty Landes geese of the same age were randomly divided into the following three groups with 20 replicates in each group: D0 group (free from gavage); D7 group (overfeeding for 7 days); D25 group (overfeeding for 25 days). At the end of the experiment, 10 geese of similar weight from each group were selected for slaughter and sampling. The results showed that overfeeding significantly increased the body weight and the liver weight of geese. Serum enzymatic activities and serum lipid levels were significantly enhanced following overfeeding. Gas chromatography time-of-flight/mass spectrometry (GC-TOF/MS) was employed to explore the serum metabolic patterns, and to identify potential contributors to the formation of fatty liver and the correlated metabolic pathways. Relative to overfeeding for 7 days, a large number of endogenous molecules in serum of geese overfed for 25 days were altered. Continuous elevated levels of pyruvic acid, alanine, proline and beta-glycerophosphoric acid and reduced lactic acid level were observed in the serum of overfed geese. Pathway exploration found that the most of significantly different metabolites were involved in amino acids, carbohydrate and lipid metabolism. The present study exhibited the efficient capability of Landes geese to produce fatty liver, identified potential biomarkers and disturbed metabolic pathways in liver steatosis. These findings might reveal the underlying mechanisms of fatty liver formation and provide some theoretical basis for the diagnosis and treatment of liver diseases.

Biogeography of microbiome and short-chain fatty acids in the gastrointestinal tract of duck.

It is generally accepted that domestic ducks are valuable protein sources for humans. The gastrointestinal ecosystem contains enormous and complicated microbes that have a profound effect on the nutrition, immunity, health, and production of domestic ducks. To deeply understand the gastrointestinal microbial composition of domestic ducks, we investigated the microbiomes of 7 different gastrointestinal locations (proventriculus, gizzard, duodenum, jejunum, ileum, cecum, and rectum) and the short-chain fatty acids in 15 healthy muscovy ducks based on 16S rRNA gene sequencing, qPCR, and gas chromatography. As a result, 1 029 735 sequences were identified into 35 phyla and 359 genera. Firmicutes, Proteobacteria, Bacteroidetes, Cyanobacteria, and Actinobacteria were the major phyla, with Bacteroidetes being most abundant in the cecum. The population of the total bacteria and the representatives of the Firmicutes, Bacteroidetes, and Bacteroides groups increased from the proximal to the distal part of the GIT. Bacteroides was the most dominant group in the cecum. Acetate, propionate, and butytrate, as well as gene copies of butyryl-CoA including acetate-CoA transferase and butyrate kinase, were significantly higher in cecum than in other sections. Isobutyrate, valerate, and isovalerate were only found in the cecum. The differences of microbial composition and the short-chain fatty acids of their metabolites among these 7 intestinal locations might be correlated with differences in gut function. All these results provide a reference for the duck gastrointestinal microbiome and a foundation for understanding the types of bacteria that promote health and enhance growth performance and decrease instances of disease in duck breeding.

Development and application of an indirect enzyme-linked immunosorbent assay using recombinant S1 for serological testing of porcine epidemic diarrhea virus.

Porcine epidemic diarrhea virus (PEDV) causes severe infectious diseases in all ages of swine and leads to serious economic losses. Serologic tests are widely accepted and used to detect anti-PEDV antibodies that could indicate PEDV infection or vaccination. In this study, PEDV recombinant S1 protein (rS1) was expressed with the Bac-to-Bac system and purified by nickel-affinity chromatography. An indirect enzyme-linked immunosorbent assay based on rS1 (rS1-ELISA) was then developed and optimized by checkerboard assays with serial dilutions of antigen and serum. Serum samples from 453 domestic pigs and 42 vaccinated pigs were analyzed by the indirect fluorescent antibody (IFA) test and rS1-ELISA. Taking IFA as a gold standard, rS1-ELISA produced a high sensitivity (90.7%) and specificity (94.6%) by a receiver operating characteristic (ROC) curve. In addition, ROC analysis also revealed that rS1-ELISA was consistent with IFA (area under the curve 0.9583 ± 0.0082). This rS1-ELISA was then applied to antibody detection in inactivated PEDV vaccinated pigs. The antibody could be detected 2-4 weeks after the first inoculation. These results indicated that the rS1-ELISA established in this study provides a promising and reliable tool for serologic detection of anti-PEDV IgG antibodies in infected or vaccinated pigs.

Nucleocapsid protein from porcine epidemic diarrhea virus isolates can antagonize interferon-λ production by blocking the nuclear factor-κB nuclear translocation.

Porcine epidemic diarrhea virus (PEDV) is a highly infectious pathogen that can cause severe diseases in pigs and result in enormous economic losses in the worldwide swine industry. Previous studies revealed that PEDV exhibits an obvious capacity for modulating interferon (IFN) signaling or expression. The newly discovered type III IFN, which plays a crucial role in antiviral immunity, has strong antiviral activity against PEDV proliferation in IPEC-J2 cells. In this study, we aimed to investigate the effect of PEDV nucleocapsid (N) protein on type III IFN-λ. We found that the N proteins of ten PEDV strains isolated between 2013 and 2017 from different local farms shared high nucleotide identities, while the N protein of the CV777 vaccine strain formed a monophyletic branch in the phylogenetic tree. The N protein of the epidemic strain could antagonize type III IFN, but not type I or type II IFN expression induced by polyinosinic-polycytidylic acid (poly(I:C)) in IPEC-J2 cells. Subsequently, we demonstrated that the inhibition of poly(I:C)-induced IFN-λ3 production by PEDV N protein was dependent on the blocking of nuclear factor-κB (NF-κB) nuclear translocation. These findings might help increase understanding of the pathogenesis of PEDV and its mechanisms for evading the host immune response.