THE SEROLOGICAL RESPONSE OF CHICKENS TO AUSTRALIAN LENTOGENIC STRAINS OF NEWCASTLE DISEASE VIRUS

SUMMARY: Australian lentogenic Newcastle disease viruses were evaluated as uninactivated vaccines in Australian chickens, the response being evaluated by the production of haemagglutination-inhibition (HI) antibodies. Two viruses, V4 and PM9, induced high levels of antibody and were readily transmissible between chickens by contact exposure. Three other viruses were poorly immunogenic and poorly transmissible. Chickens vaccinated intramuscularly with the V4 strain produced higher HI antibody titres than chickens vaccinated by the orotracheal, intranasal and intraocular routes. HI antibody titres in chickens vaccinated with the V4 strain reached peak levels 3 to 5 weeks after vaccination and waned considerably during the next 2 to 4 weeks. However, low levels of HI antibody persisted for at least 36 weeks after vaccination. Intramuscular vaccination with the V4 strain of one-day-old chicks lacking maternal antibody to Newcastle disease virus resulted in 42–70% mortality and the survivors developed very high titres of HI antibody. Similar chickens inoculated orotracheally showed signs of depression and developed high titres of HI antibody, but there were no mortalities. Chickens 1-, 2-, 3- and 4-weeks-old and lacking maternally derived HI antibody to Newcastle disease virus suffered no adverse reaction to intramuscular or orotracheal vaccination. The antibody response of the 1-week-old chickens was considerably poorer than that of the older chickens. Following orotracheal vaccination with the V4 strain, chickens with low levels of maternally derived antibody responded with low levels of HI antibody. On the other hand, in the progeny of hens hyperimmunised with the V4 strain the production of active antibody following orotracheal vaccination was delayed until the level of passive antibody had declined considerably. There was no response to intramuscular vaccination in congenitally hyperimmune chickens. The minimum HI antibody inducing dose of V4 vaccine, when measured 3 weeks after vaccination of 6-weeks-old chickens, was 10^5.6 50% egg infectious doses.     

Methionine requirement of pigs between 5 and 20 kilograms body weight.

Four nursery experiments were conducted using a methionine (Met)-deficient feather meal-corn-soybean meal-dried whey basal diet (20% CP; 3,250 kcal of ME/kg, .11% choline, .19% Met, 1.00% cystine) supplemented with lysine, tryptophan, and histidine to determine the Met requirement of 5- to 10- and 10- to 20-kg pigs. Based on a true Met digestibility value of 81.6% estimated by a pig ileal digestibility assay, the Met-deficient basal diet contained .155% of digestible Met. A preliminary experiment (Exp. 1) indicated that pigs fed the Met-deficient basal diet when fortified adequately with Met could produce weight gains similar to those of pigs fed a 20% CP practical corn-soybean meal-dried whey diet. In Exp. 2 and 3, crossbred pigs weighing 5.8 kg initially were fed diets containing graded levels of digestible Met between .195 and .355%. Average daily gain increased quadratically (P less than .05) as the level of Met increased. When the data of Exp. 2 and 3 were examined together, the digestible Met requirement of 5- to 10-kg pigs was estimated to be .255% of the diet. In Exp. 4 and 5, crossbred pigs averaging 10 kg were fed digestible Met concentrations ranging from .155 to .315%. Average daily gain increased quadratically (P less than .05). The digestible Met requirement of 10- to 20-kg pigs was estimated at .255% for maximal weight gain, which was similar to that of 5- to 10-kg pigs. Assuming an 89% digestibility of Met in practical corn-soybean meal diets, the total Met level needed in practice would be .29%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Receptor-dependent and independent degradation of insulin by isolated swine adipocytes at 37 C

Insulin binding and degradation were measured at 37 C in isolated swine adipocytes. In preliminary experiments, binding decreased rapidly with increasing incubation time. This was associated with a marked increase in insulin degradation. Insulin binding was suppressed by some lots of bovine serum albumin (BSA), which suggests that some commercial preparations of BSA are contaminated with insulin-like molecules. In adipocyte suspensions, greater than 90% of the insulin degraded was due to a nonreceptor mediated process (i.e., insulin degrading activity present in the media). Despite the presence of insulin degrading activity in the media the cells were metabolically (as judged by lipogenic capacity and lactic dehydrogenase activity) and morphologically (greater than 98% excluded trypan blue) intact indicating that the cells were not leaking during the incubation. In subsequent experiments it was found that the specific step associated with transfer of cells during adipocyte isolation resulted in the release of insulin degrading activity. Implementation of a 30-min preincubation and washing sequence after adipocyte isolation removed the media insulin degrading activity, resulting in a marked reduction (approximately 70%) of insulin degradation by adipocyte suspensions. As a result of this modification, binding of tracer quantities of insulin attained steady-state binding conditions and maintained this for 2 h. These results demonstrate that techniques can be used to minimize nonreceptor mediated insulin degradation in adipocyte suspensions. As a result in vitro studies can be conducted that measure insulin binding and biological action in swine adipocytes at physiological temperatures.     

Antioxidant evaluation and oxidative stability of structured lipids from extravirgin olive oil and conjugated linoleic acid

Structured lipid (SL) was synthesized from extravirgin olive oil (EVOO) and conjugated linoleic acid (CLA) via a lipase-catalyzed reaction. CLA provides a variety of health benefits, but it is not consumed in free fatty acid form. The synthesized SL olive oil contained 42.5 mol % CLA isomers, and the major isomers were cis-9,trans-11-CLA (16.9 mol %) and trans-10,cis-12-CLA (24.2 mol %). The antioxidant activity determined by the radical scavenging capacity with the 2,2-diphenyl-1-picrylhydrazyl radical was lower in SL olive oil than in EVOO. The oxidative stability was also lower in SL olive oil since it had a higher peroxide value, rho-anisidine value, and 2-thiobarbituric acid reactive substances values during 20 days of storage at 60 degrees C. This observation could be due to the reduction in the natural phenolic compounds (97%) and tocopherols (56%), and the incorporated CLA with two conjugated double bonds in the SL olive oil. The oxidative stability of SL olive oil was increased by added rosemary extracts at concentrations of 100, 200, and 300 ppm. The present study suggests that the SL olive oil may be a suitable way to incorporate or deliver CLA into human diets. However, the addition of a proper antioxidant would be required for improving its oxidative stability.     

Characterization of three Colletotrichum acutatum isolates from Capsicum spp.

Colletotrichum acutatum causes anthracnose on peppers (Capsicum spp.), resulting in severe yield losses in Taiwan. Fungal isolates Coll-153, Coll-365 and Coll-524 collected from diseased peppers were found to differ in pathogenicity. Pathogenicity assays on various index plants revealed that Coll-524 was highly virulent and Coll-153 was moderately virulent to three commercially available pepper cultivars. Both isolates induced anthracnose lesions and produced abundant conidia. Coll-365 was only weakly virulent on pepper fruit, where it caused small lesions and hardly produced conidia on pepper fruit. However, Coll-365 was highly pathogenic to tomato fruit and mango leaves, where it caused anthracnose lesions and formed acervuli and conidia. All three isolates showed similar abilities in the attachment and germination of conidia, formation of highly branched hyphae and appressoria, penetration of cuticles, and infection of epidermal cells on chili peppers. Coll-365 accumulated less turgor pressure in appressoria but produced higher levels of cutinase and protease activity than Coll-153 and Coll-524 did. All three isolates invaded the neighbouring cells through plasmodesmata in chili peppers and showed similar pectinase or cellulase activities in culture. However, the most virulent strain Coll-524 expressed stronger laccase activity and was more resistant to capsaicin compared to Coll-153 and Coll-365. The three isolates are different in numbers and sizes of double-stranded RNAs. Depending on the cultivar genotypes, cellular resistance of chili pepper to C. acutatum might rely on the ability to restrict penetration, colonization, or conidiation of the pathogen. We conclude that the differences in pathogenicity among the three C. acutatum isolates of pepper are attributed to their ability to colonize the host plant.     

Osteogenic proliferation and differentiation of canine bone marrow and adipose tissue derived mesenchymal stromal cells and the influence of hypoxia

The aim of this study was to compare the osteogenic and proliferative potential of canine mesenchymal stromal cells (cMSCs) derived from bone marrow (BM-cMSCs) and adipose tissue (AT-cMSCs). Proliferation potential was determined under varying oxygen tensions (1%, 5%, and 21% O(2)). Effects of reduced oxygen levels on the osteogenic differentiation of AT-cMSCs were also investigated. AT-cMSCs proliferated at a significantly faster rate than BM-cMSCs, although both cell types showed robust osteogenic differentiation. Culture in 5% and 1% O(2) impaired proliferation in cMSC from both sources and osteogenic differentiation in AT-cMSCs. Our data suggests that AT-cMSCs might be more suitable for use in a clinical situation, where large cell numbers are required for bone repair, due to their rapid proliferation combined with robust osteogenic potential. Our data also suggests that the inhibitory effects of hypoxia on both cell proliferation and differentiation should be considered when using MSCs in a potentially hypoxic environment such as a fracture site.     

Immunoproteomic analyses of outer membrane antigens of Actinobacillus pleuropneumoniae grown under iron-restricted conditions

Actinobacillus pleuropneumoniae, a bacterial pathogen of swine and agent of porcine pneumonia, causes a highly infectious disease of economic importance in the pig industry. Commercial vaccines for A. pleuropneumoniae include whole-cell bacterins and second generation subunit vaccines but they only confer partial protective immunity. Our search for new vaccine candidates identified antigens that are expressed during conditions that mimic infection; the outer membrane (OM) proteome of A. pleuropneumoniae serotype 5b was examined under iron restriction. Quantitative profiling by 2D-DiGE technology revealed that iron restriction induced expression of previously described transferrin binding proteins (TbpA, TbpB) plus four lipoproteins including spermidine/putrescine binding periplasmic protein 1 precursor (PotD2). Immunoproteomic analyses with antisera from na?ve animals and from infected pigs were able to differentiate antigens within the OM proteome that were specifically recognized during A. pleuropneumoniae infection. Immunoblots of iron-restricted profiles detected PotD2, heme-binding protein A (HbpA), and capsule polysaccharide export protein (CpxD) as well as surface antigens TbpA, TbpB, and OmlA. These data identify OM proteins that demonstrate immunogenicity and upregulation under conditions mimicking infection, providing emphasis on lipoproteins as an important class of antigens to exploit for vaccine development for A. pleuropneumoniae.     

Exendin-4 improves resistance to Listeria monocytogenes infection in diabetic db/db mice

The incidence of diabetes mellitus is increasing among companion animals. This disease has similar characteristics in both humans and animals. Diabetes is frequently identified as an independent risk factor for infections associated with increased mortality. In the present study, homozygous diabetic (db/db) mice were infected with Listeria (L.) monocytogenes and then treated with the anti-diabetic drug exendin-4, a glucagon-like peptide 1 analogue. In aged db/db mice, decreased CD11b⁺ macrophage populations with higher lipid content and lower phagocytic activity were observed. Exendin-4 lowered high lipid levels and enhanced phagocytosis in macrophages from db/db mice infected with L. monocytogenes. Exendin-4 also ameliorated obesity and hyperglycemia, and improved ex vivo bacteria clearance by macrophages in the animals. Liver histology examined during L. monocytogenes infection indicated that abscess formation was much milder in exendin-4-treated db/db mice than in the control animals. Moreover, mechanistic studies demonstrated that expression of ATP binding cassette transporter 1, a sterol transporter, was higher in macrophages isolated from the exendin-4-treated db/db mice. Overall, our results suggest that exendin-4 decreases the risk of infection in diabetic animals by modifying the interaction between intracellular lipids and phagocytic macrophages.