Rapid molecular typing of Listeria monocytogenes by pulsed-field gel electrophoresis

Effect of in ovo administration of Newcastle disease vaccine conjugated with Astragalus polysaccharide on growth performance, intestinal development, and mucosal immunity in broiler chickens

This study was conducted to investigate the effect of in ovo administration of a mixture of Astragalus polysaccharide (APS) and Newcastle disease vaccine (NDV) on growth performance, intestinal development, and mucosal immunity in newly hatched chicks. Six hundred specific-pathogen-free (SPF) Leghorn fertilised eggs were incubated in a commercial hatchery and divided into four groups: (a) control group injected with 1 ml of 0.9% physiological saline, (b) APS group injected with 1 ml of 1 mg/ml APS solution, and (c) NDV group injected with 1 ml of 10^4.0 EID₅₀ /dose of NDV solution, and (d) APS + NDV group injected with a mixture of 0.5 ml of 2 mg/ml APS plus 0.5 ml 10^4.0 EID₅₀ /dose ND vaccine (NDV) on Day 18.5 of incubation. The results showed that in ovo injection of APS or the mixture of APS and NDV increased the body weight at 1 day (IW) and final weight (FW) at 28 days and increased the feed conversion ratio (FCR) at 1-7, 8-14, 15-21, and 1-28 days of age. The villus height (VH) was increased (p < 0.05), and the crypt depth (CD) was decreased (p < 0.05) in the duodenum compared with the control group. The VH/CD ratios were increased (p < 0.05) in the APS + NDV group compared with controls, NDV group, and APS group on d3. The levels of slgA in washings were increased (p < 0.05) on Days 3, 7, 14, 21, and 28, and the number of IgA⁺ cells in the duodenum was increased on Days 7, 14, 21, and 28. In addition, the IgA⁺ cells were promoted from the villus root to the apex in the APS + NDV group. It can be concluded that in ovo administration of NDV conjugated with APS compared with NDV alone may be more effective in promoting growth performance and intestinal mucosal immunity.

Effect of Oils in Feed on the Production Performance and Egg Quality of Laying Hens

With the development of a large-scale and intensive production industry, the number of laying hens in China is rapidly increasing. Oils, as an important source of essential fatty acids, can be added to the diet to effectively improve the production performance and absorption of other nutrients. The present review discusses the practical application of different types and qualities of oils in poultry diets and studies the critical effects of these oils on production performance, such as the egg weight, feed intake, feed conversion ratio (FCR), and various egg quality parameters, including the albumen height, Haugh units, yolk color, and saturated/unsaturated fatty acids. This article reviews the effects of different dietary oil sources on the production performance and egg quality of laying hens and their potential functional mechanisms and provides a reference for the selection of different sources of oils to include in the diet with the aim of improving egg production. This review thus provides a reference for the application of oils to the diets of laying hens. Future studies are needed to determine how poultry products can be produced with the appropriate proper oils in the diet and without negative effects on production performance and egg quality.

Cyclooxygenase-2 Facilitates Newcastle Disease Virus Proliferation and Is as a Target for Canthin-6-One Antiviral Activity

Cyclooxygenase-2 (COX-2), one of the mediators of inflammation in response to viral infection, plays an important role in host antiviral defense system. But its role in Newcastle disease virus (NDV) proliferation process remains unclear. This study revealed that inhibition of COX-2 could benefit NDV proliferation and overexpression of COX-2 dose-dependently suppressed NDV proliferation. Overexpression of COX-2 also showed inhibitory effect on NDV-induced endoplasmic reticulum (ER)-stress and autophagy, also promoted the expression of antiviral genes. However, prostaglandin E₂ (PGE₂), the major product of COX-2, had indistinctive effects on NDV proliferation. At variant time point post viral infection, a tight regulation pattern of COX-2 by NDV was observed. Using inhibitors and siRNA against signaling molecules, the nuclear factor-κB (NF-κB) and melanoma differentiation-associated gene 5 (MDA5) were identified as critical factors for NDV induced COX-2 expression. Nonetheless, at late stage of NDV proliferation, substantial suppression of COX-2 protein synthesis could be detected, accompanied by a decrease in mRNA half-life. Furthermore, three C ring-truncated canthin-6-one analogs were used to activate COX-2 expression and showed inhibitory effect on NDV proliferation with the effective concentrations on μM level. Taken together, these results illustrated a novel NDV-regulated cellular mechanism and indicated that COX-2 is an important regulator of NDV proliferation which can serve as a potential target for anti-NDV agents.

Characteristics and Epidemiologic Genotyping of Staphylococcus aureus Isolates from Bovine Mastitic Milk in Hokkaido, Japan

Two hundred thirty one Staphylococcus aureus isolates from bovine mastitic milk were discriminated into 60 patterns and 16 lineages by pulsed-field gel electrophoresis (PFGE). The tested isolates were also investigated using coagulase and capsule serotyping and PCR for possession of genes that encode staphylococcal enterotoxins (sea to sei), enterotoxin-like toxins (selj to selr), and toxic shock syndrome toxin (tst). One hundred seventy three of the isolates (74.9%) possessed one or more toxin genes, while no egg-yolk factor was detected in most of them. The most common combinations of toxin genes possessed by the tested isolates were sec, seg, sei, sell, and tst, or seg and sei, or sec, seg, sei, sell, seln, and tst. Two hundred and ten of the isolates (91.0%) serotyped coagulase VI, and 207 of the isolates (89.6%) expressed serotype 5 or 8 capsules. These results suggested that isolates belonging to two major lineages have spread all over Hokkaido as bovine mastitic isolates. Additionally, no remarkable difference was recognized in the identification ratio of the isolates that belonged to the two major lineages between mastitis of subclinical origin and mastitis of clinical origin.

Identification of Listeria species by microarray-based assay

We have developed a rapid microarray-based assay for the reliable detection and discrimination of six species of the Listeria genus: L. monocytogenes, L. ivanovii, L. innocua, L. welshimeri, L. seeligeri, and L. grayi. The approach used in this study involves one-tube multiplex PCR amplification of six target bacterial virulence factor genes (iap, hly, inlB, plcA, plcB, and clpE), synthesis of fluorescently labeled single-stranded DNA, and hybridization to the multiple individual oligonucleotide probes specific for each Listeria species and immobilized on a glass surface. Results of the microarray analysis of 53 reference and clinical isolates of Listeria spp. demonstrated that this method allowed unambiguous identification of all six Listeria species based on sequence differences in the iap gene. Another virulence factor gene, hly, was used for detection and genotyping all L. monocytogenes, all L. ivanovii, and 8 of 11 L. seeligeri isolates. Other members of the genus Listeria and three L. seeligeri isolates did not contain the hly gene. There was complete agreement between the results of genotyping based on the hly and iap gene sequences. All L. monocytogenes isolates were found to be positive for the inlB, plcA, plcB, and clpE virulence genes specific only to this species. Our data on Listeria species analysis demonstrated that this microarray technique is a simple, rapid, and robust genotyping method that is also a potentially valuable tool for identification and characterization of bacterial pathogens in general.

Use of PFGE typing for tracing contamination with Listeria monocytogenes in three cold-smoked salmon processing plants

The sites of Listeria monocytogenes contamination in three cold-smoked salmon (Salmo salar) processing plants were detected by sampling salmon and the plant's environment and equipment at different production stages. Of the 141 samples collected from three processing plants, 59 (42%) were contaminated with L. monocytogenes. The rates of contamination varied as to the plant and the sample source. L. monocytogenes isolates from 17 various contaminated seafood products (fresh, frozen and smoked fishes, cooked mussels) were also studied. A total of 155 isolates from the three plants and the various seafoods were characterized by genomic macrorestriction using ApaI and SmaI with pulsed-field gel electrophoresis (PFGE) and 82 isolates were serotyped. Macrorestriction yielded 20 pulsotypes and serotyping yielded four serovars: 1/2a, 1/2b, 1/2c, 4b (or e), with 77 (93%) belonging to serovar 1/2a. One clone of L. monocvtogenes predominated and persisted in plant I and was the only pulsotype detected in the final product although it was not isolated from raw salmon. No L. monocytogenes was detected in the smoked skinned salmon processed in plant II, even though 87% of the raw salmon was contaminated. All the smoked salmon samples collected in plant III were contaminated with a unique clone of L. monocytogenes, which may have occurred during slicing. In the three plants, the contamination of final products did not seem to originate from the L. monocytogenes present on raw salmon, but from the processing environment.