Seroconversion to avian influenza virus in free-range chickens in the Riverland region of Victoria

Background Since 2005, H5N1 avian influenza (AI) has spread from South-East Asia to over 60 different countries, resulting in the direct death or slaughter of over 250,000,000 poultry. Migratory waterfowl have been implicated in this spread and in Australia there have been numerous isolations of low-pathogenicity AI virus from wild waterfowl and shorebirds. The Department of Human Services, Victoria maintains 10 sentinel free-range chicken flocks in the Riverland at locations that are populated by large numbers of waterfowl known to carry a range of strains of AI. Objective This study analysed historical samples collected in 1991–94 and 2003–06 from the library of serum samples for antibodies against AI to assess the potential for transfer of AI virus from wild waterfowl to free-range poultry. Results Of the 2000 serum samples analysed, 17 were positive for antibodies against AI and 87 were suspect, with a clustering of positive and suspect results in the years 1994, 2003 and 2004. There was also a clustering of positive samples at the site of the Barmah flock. Nine sequential sets of sera from individual chickens with at least one positive result were identified. Analysis of these sequential sets showed that infection was acquired on site but that the antibody response to AI infection was short-lived and was no longer detectable at 8 weeks after the positive finding. Conclusion The surveillance of sentinel chickens is a potential avenue for monitoring the circulation of AI viruses and could provide an early warning system for the commercial poultry industries.     

Septic arthritis,navicular bursitis and osseous cyst‐like lesion in a foal

The purpose of this report is to describe the clinical, imaging and pathological findings in a Quarter Horse colt admitted to the Texas A&M University Veterinary Medical Teaching Hospital for lameness of the left forelimb and left hindlimb. A presumptive diagnosis of left forelimb septic navicular bursitis was made ultrasonographically. A cyst‐like lesion of the calcaneus was diagnosed radiographically and better characterised with computed tomography. The cyst‐like lesion of the calcaneus was caused by infection with Actinobacillus sp. and extended into the adjacent tarsocrural, proximal intertarsal and talocalcaneal joints causing septic arthritis. The owner elected for euthanasia due to the poor prognosis. The diagnoses were confirmed on histopathology.     

Derivation, characterization and differentiation of buffalo (Bubalus bubalis) amniotic fluid derived stem cells

Amniotic fluid cells (AFCs) are obtained from amnion for pre-natal analysis and can be cultured in vitro. Heterogeneous amniotic fluid (AF) contains various cell types, and it is believed that some of these cells possess the stem cell properties. The aim of this study was to characterize these cells by phenotypical and genotypical means in buffalo. The differentiation potential of amniotic fluid stem (AFS) cells was carried out by converting these cells into neurons. The AFCs were cultured without feeder cells in DMEM containing 16% foetal bovine serum, 1% penicillin/streptomycin and 1%l-glutamine in 5% CO(2) at 38.5 ± 0.5 °C in a CO(2) incubator. After 6 days of culture, different types of cells viz., star shaped (62.7%), spherical without nucleus (1.9%), spherical with nucleus (26.4%), pentagonal (0.4%) and free floating/rounded cells (8.3%) were observed. Most of the cells started anchorage-dependent growth after day 7 of the culture. Expression of Oct-4, Sox-2, Nanog, alkaline phosphatase, 18s rRNA, stem cell factor, cyclin A, Nestin and FGF-5 was observed from the AFS cells in different passages with PCR amplicon of 314, 277, 317, 180, 162, 216, 421, 307 and 210 bp, respectively. During the differentiation step, at day 6, neuron-like cells could be clearly identified and confirmed with Nestin-specific RT-PCR. The cells were found to have a normal karyotype at different passages. These results may contribute towards establishing non-embryonic pluripotent stem cells for various therapeutic and reproductive biotechnological applications in the species.     

Role of leukotriene B4 in the pathogenesis of Klebsiella pneumoniae-induced bovine mastitis

Mastitis was induced in 4 lactating cows by inoculation of Klebsiella pneumoniae (10(7) organisms/ml) via the teat canal. Sterile isotonic saline solution (1 ml) was instilled into designated control quarters via the teat canal. Changes in milk leukotriene B4 and C4 (LTB4, LTC4) concentrations, milk somatic cell counts, and milk bovine serum albumin concentration were monitored over a 24-hour postinoculation period. Milk LTB4 concentration before inoculation in control quarters and quarters later to be infected was 376 +/- 45 and 326 +/- 56 pg/ml of milk, respectively. A significant (P less than 0.05) increase in milk LTB4 concentration in the infected quarters was first observed at postinoculation hour 6, and milk LTB4 concentration in infected quarters generally remained significantly high through postinoculation hour 14. Thereafter, milk LTB4 concentration in infected quarters was not significantly different from the concentration in control quarters. Measurable amounts of LTC4 were not detected in the milk of either control or infected quarters. Milk bovine serum albumin concentration in the infected quarters generally was high throughout the study, as were milk somatic cell counts. The results of this study suggested that LTB4 contributes to the pathogenesis of bovine mastitis.     

Larval Age at Stocking,Growth, and Survival During Fingerling Production of the Endangered Sun Catfish,Horabagrus brachysoma

An experiment was conducted to ascertain the initial rearing period required for Horabagrus brachysoma larvae before releasing them into the nursery tank for fingerling production. Hatchlings were reared for 7, 14, or 21 days in larval rearing tanks before stocking to nursery tanks. The 7-day-old larvae were significantly smaller at the end of the 2-week nursery rearing, but over the course of nursing, the 7-day-old larvae caught up to the 14- and 21-day larvae. The specific growth rate (SGR) of 7-day larvae was highest among the three treatments. However, mortality of 7-day larvae was the highest among the groups. Hence, it appears important to rear the larvae at least 2 weeks before stocking for fingerling production so as to increase survival rate.     

Effects of dietary supplementation of potential probiotic Bacillus subtilis VSG1 singularly or in combination with Lactobacillus plantarum VSG3 or/and Pseudomonas aeruginosa VSG2 on the growth,immunity and disease resistance of Labeo rohita

Labeo rohita fingerlings were fed for 60 days with basal diet (BD) or one of the following experimental diets: DI (BD + B. subtilis); DII (BD + B. subtilis + L. plantarum); DIII (BD + B. subtilis + P. aeruginosa) and DIV (BD + B. subtilis + P. aeruginosa + L. plantarum). Various growth and immune parameters were examined at 30 and 60 days postfeeding. The fish group fed DIV diet had better improvement (P < 0.05) in weight gain, specific growth rate (SGR) and feed conversion ratio (FCR) than the control and other treatment groups. The serum lysozyme activities, alternative complement pathway activity, phagocytic activity and respiratory burst activity in head kidney macrophages of L. rohita increased significantly in the experimental groups throughout the trial period. Superoxide dismutase increased significantly in the experimental groups, except DI fed group, after 60 days of feeding. A significant improvement in serum IgM level was observed in the treatment groups at 30 days of feeding only. Further, fish fed the DIV diet had highest (P < 0.05) postchallenge survival rate (86.6%), followed by DII (73.3%) and DIII (66.6%) against A. hydrophila infection. Considering these promising results, we suggest that a multi‐species probiotic supplementation in equal proportions for 60 days can effectively improve growth and immunity of L. rohita.     

Effects of allergen challenge on plasma concentrations of prostaglandins, thromboxane B2, and histamine in calves infected with bovine respiratory syncytial virus.

To examine the influence of allergen-induced type-1 hypersensitivity on the pathogenesis of bovine respiratory syncytial virus (BRSV) infection, we sensitized calves by aerosol to Micropolyspora faeni (MF) and challenge exposed them during infection with BRSV. The development of MF-specific IgE serum concentrations was confirmed by ELISA. The dynamics of arachidonic acid metabolism and histamine release during a type-1 hypersensitivity reaction in the bovine lung were studied by quantitating the concentrations of prostaglandin (PG)E2, PGF2 alpha, PGI2 as 6-keto-PGF1 alpha, thromboxane (TX) A2 as TXB2, and histamine in plasma of BRSV-infected and/or MF-sensitized/challenge-exposed calves. Four treatment groups were established: (1) BRSV infection only, (2) aerosol sensitization to MF followed by BRSV infection and aerosol challenge exposure to MF, (3) MF aerosol sensitization and challenge exposure without BRSV infection, and (4) aerosol sensitization to MF followed by BRSV infection without MF challenge exposure. Significantly increased concentrations of PGI2 were associated with MF aerosol exposure, particularly when combined with BRSV infection in group 2. After MF challenge exposure, TXB2 concentrations were significantly greater in the virus and MF challenge-exposed group 2. Individual calf data for the change in MF-specific IgE concentration between the first and second MF challenge exposures and the change in PGE2 concentration 30 minutes after the second MF challenge exposure had a highly significant direct correlation. Histamine concentrations were significantly greater in calves infected with BRSV than in uninfected controls regardless of MF exposure. These data further substantiate the thesis that implicates type-1 hypersensitivity as a pathogenic mechanism in BRSV-related disease.