Acute monocytic leukemia in an irradiated Beagle.

A purebred female Beagle dog that had received 2,000 R of protracted wholebody gamma-irradiation from 60Co when 14 months old had hematologic changes consistent with a myeloproliferative disorder 3 years after the termination of radiation exposure. Peripheral blood and bone marrow findings during the 7-month period before death showed progressive anemia with increased numbers of platelets; immature granulocytes, monocytes and promonocytes. A period of partial remission occurred during which time the peripheral blood was aleukemic, although there was marked thrombocytosis and abnormal erythropoiesis which was evidenced by bizarre circulating nucleated red cells, anisocytosis, poikilocytosis and Howell-Jolly bodies. The dog had a terminal crisis with marked leukocytosis, most cells in the peripheral blood being bizarre monocytes and promonocytes. Tissues obtained at necropsy showed diffuse as well as focal infiltration of the spleen, liver, lymph nodes, heart, kidney and gastrointestinal wall with immature neoplastic cells resembling monocytes and monocytic precursors. The monocytic differentiation of the invasive cell population was confirmed by morphological, cytochemical, histological, ultrastructural and in vitro cell culture studies.     

Assessment of the Long-Term Viability of the Myxospores of Myxobolus cerebralis as Determined by Production of the Actinospores by Tubifex tubifex

While whirling disease was first observed in Rainbow Trout Oncorhynchus mykiss in 1893, the complete life cycle of Myxobolus cerebralis (Mc), the causative agent of the disease, was not understood until 1984, when it was shown to involve two obligate hosts, a salmonid fish and the aquatic oligochaete Tubifex tubifex (Tt). The viability of the triactinomyxon (TAM) actinospores produced by Tt has been well studied, and is known to be temperature dependent and measured in days and weeks. Assertions that Mc myxospores produced by infected fish remain viable for years or even decades were made during the mid-20th century, decades before the Mc life cycle was described. Moreover, the duration of myxospore viability has not been well studied since the life cycle was elucidated. In a series of time-delay treatments, we assessed the long-term viability of Mc myxospores by exposure to Mc-susceptible Tt oligochaetes and quantified TAM production. As the time delay between inoculation and incubation of Mc myxospores in sand and water and exposure to Tt oligochaetes increased, TAM production decreased exponentially. Production among the 15-d time-delay replicates was reduced 74.7% compared with the 0-d treatment. Likewise, total TAM production was reduced 94.5, 99.4, and 99.9%, respectively, in the 90-, 120-, and 180-d time-delay treatments. Linear regression analysis of our data and the absence of TAM production among replicates of Mc myxospores held at 5°C for 365 d prior to exposure to Mc-susceptible Tt oligochaetes indicate that the long-term viability of Mc myxospores is less than 1 year under the conditions of this study.

Received May 14, 2014; accepted September 27, 2014     

Optimizing the growth of forage and grain legumes on low pH soils through the application of superior Rhizobium leguminosarum biovar viciae strains

Climate variability and current farming practices have led to declining soil fertility and pH, with a heavy reliance on fertilizers and herbicides. The addition of forage and grain legumes to farming systems not only improves soil health but also increases farm profitability through nitrogen (N) fertilizer cost offsets. However, the formation of effective symbioses between legumes and rhizobia can be unreliable and is considered at risk when combined with dry sowing practices such as those that have been designed to obviate effects of climate change. This research was initiated to improve the robustness of the legume/rhizobia symbiosis in low pH, infertile and dry soils. Production from two cultivars of field pea (Pisum sativum) and two species of vetch (Vicia spp.), and symbiotic outcomes when inoculated with a range of experimental rhizobial strains (Rhizobium leguminosarum biovar viciae), was assessed in broad acre field trials which simulated farmer practice. New rhizobia strains increased nodulation, N fixation, produced more biomass and higher seed yield than comparator commercial strains. Strain WSM4643 also demonstrated superior survival when desiccated compared to current commercial strains in the laboratory and on seed when delivered as inoculant in peat carriers. WSM4643 is a suitable prospect for a commercial inoculant in Australia and other agricultural areas of the world where growing peas and vetch on soils generally considered problematic for this legume/rhizobia symbiosis. A particular advantage of WSM4643 may be that it potentiates sowing inoculated legumes into dry soil, which is a contemporary response by farmers to climate variation.     

Protection of piglets against a virulent New Zealand isolate of Aujeszky's disease virus by vaccination with a novel genetically-engineered vaccine

Abstract

AIMS: To modify and validate an existing swine erysipelas ELISA for use with poultry serum and to assess the safety of a swine erysipelas vaccine for use in New Zealand layer birds.

METHODS: An existing swine erysipelas ELISA was modified for use in domestic poultry and was validated using sera from birds injected with either 2 mL of a commercially available killed swine erysipelas vaccine (low-dose; n=12 birds), 4 mL of vaccine (high-dose; n=11 birds), or 2 mL saline (control; n=11 birds) on Day 0 and again on Day 21. Blood samples were collected on Days 0, 21, 42, and 63, and safety of the vaccine for use in layer birds was determined by assessing cloacal temperature and injection site reactions in birds at 0, 4, 24, 48, 72 and 96 h post-vaccination.

RESULTS: The ELISA that was developed had a diagnostic sensitivity and specificity of 93% and 98%, respectively, after being optimised for a positive cut-off at an optical density (OD) ≥1.50 read at 450-nm wavelength. OD readings were higher on Days 21, 42, and 63 than Day 0 in both the low-dose and high-dose groups (p<0.05), and differed amongst the three groups on Days 21, 42, and 63 (p<0.05), suggesting that vaccination using either dose induced detectable levels of antibody, even after a single dose. In addition, the high-dose protocol induced higher levels of antibody production than the low-dose protocol. No local or systemic reactions to the vaccine were observed and cloacal temperatures remained in the normal biological range after vaccination.

CONCLUSIONS: The ELISA that was developed had satisfactory diagnostic performance characteristics and the vaccine appeared to be safe for use in layer birds. However, the study design did not permit an assessment of the vaccine's efficacy to protect birds from clinical erysipelas.

CLINICAL RELEVANCE: A diagnostic ELISA has been developed for determining the exposure of layer birds to E. rhusiopathiae. The test will be useful for monitoring flock-level erysipelas, response to vaccination, and in epidemiological studies designed to identify risk factors for exposure to the disease.     

Assessment of inoculation methods to identify resistance to Fusarium crown rot in wheat

Journal of Plant Diseases and Protection - Crown rot, caused by Fusarium culmorum and Fusarium pseudograminearum, is one of the most pervasive diseases of wheat throughout the world. Fusarium...     

Prevention of Brca1-mediated mammary tumorigenesis in mice by a progesterone antagonist

Women with mutations in the breast cancer susceptibility gene BRCA1 are predisposed to breast and ovarian cancers. Why the BRCA1 protein suppresses tumor development specifically in ovarian hormone-sensitive tissues remains unclear. We demonstrate that mammary glands of nulliparous Brca1/p53-deficient mice accumulate lateral branches and undergo extensive alveologenesis, a phenotype that occurs only during pregnancy in wild-type mice. Progesterone receptors, but not estrogen receptors, are overexpressed in the mutant mammary epithelial cells because of a defect in their degradation by the proteasome pathway. Treatment of Brca1/p53-deficient mice with the progesterone antagonist mifepristone (RU 486) prevented mammary tumorigenesis. These findings reveal a tissue-specific function for the BRCA1 protein and raise the possibility that antiprogesterone treatment may be useful for breast cancer prevention in individuals with BRCA1 mutations.     

Toll‐like receptor and related cytokine mRNA expression in bovine corpora lutea during the oestrous cycle and pregnancy

Improving our understanding of the mechanisms controlling the corpus luteum (CL) and its role in regulating the reproductive cycle should lead to improvements in the sustainability of today's global animal industry. The corpus luteum (CL) is a transient endocrine organ composed of a heterogeneous mixture steroidogenic, endothelial and immune cells, and it is becoming clear that immune mechanisms play a key role in CL regulation especially in luteolysis. Toll‐like receptors (TLR) mediate innate immune mechanisms via the production of pro‐inflammatory cytokines, especially within various tissues, although the role of TLR within CL remains unknown. Thus, the objectives of this study were to characterize TLR mRNA expression in the CL during the oestrous cycle and in pregnancy (day 30–50), and to examine the role of TLR signalling in luteal cells. Corpora lutea were collected at various stages of the cycle and pregnancy and analysed for TLR and cytokine mRNA expression. In addition, luteal cells were cultured with the TLR4 ligand (lipopolysaccharide, LPS) for 24 h to evaluate the role of TLR4 in regulating luteal function. Toll‐like receptors 1, 2, 4, 6, tumour necrosis factor alpha (TNF), interferon gamma (IFN‐G), and interleukin (IL)‐12, mRNA expressions were greatest in regressing CL compared with earlier stages (p < .05), whereas no change was observed for IL‐6 mRNA expression. Cytokine mRNA expression in cultured luteal cells was not altered by LPS. Based on these data, one or more of the TLRs found within the CL may play a role in luteolysis, perhaps via pro‐inflammatory cytokine mRNA expression.     

Comparison of the Johne''s absorbed EIA and the complement-fixation test for the diagnosis of Johne''s disease in cattle

A commercially available absorbed ELISA for the diagnosis of Johne's disease (JD) (paratuberculosis) in cattle, the Johne's Absorbed EIA, was compared with the conventional complement-fixation test (CFT) used in Australia. Stored plasma from 3 Victorian dairy herds with a history of JD, sera from specimens submitted from animals showing clinical signs of JD and sera from the US National Repository for Paratuberculosis Specimens were used to determine the sensitivity of each test. The EIA detected 48.8% of 43 Australian animals with subclinical JD, while the CFT detected only 12 (21.4%) of 56 subclinically affected cattle. Of 150 subclinically infected US cattle, the EIA detected 47.3% and the CFT detected 52.0%. The EIA detected 59.7% of animals which at the time of sampling were shedding Mycobacterium paratuberculosis in their faeces, but showed no clinical signs of JD, while the CFT detected 57.3%. The EIA correctly identified 88.2% of 136 histologically confirmed clinical cases, and the CFT detected 83.4%. The specificity of each test was determined by testing sera collected at slaughter from animals residing in a known JD-free area of Australia, and from samples from the US National Repository of Paratuberculosis Specimens collected from certified-free herds in Wisconsin. The EIA was found to have a specificity of 99.8% when 998 Australian animals were used as the test population, and 99.0% when 196 US animals were used. The specificity of the CFT using Australian samples was 96.9% and 95.2% using American samples.     

Attitudes of veterinarians to undergraduate education in genetics and the use of genetics in veterinary occupations

A questionnaire regarding attitudes to undergraduate education in genetics and the subsequent use of that education was sent to 1000 veterinarians registered in New South Wales. Three hundred replies to the questionnaire were received and analysed. No significant difference in the perceived adequacy of courses at the four universities involved in teaching veterinary science was observed. Opinions on adequacy of education in genetics were not affected by age, sex or years since graduation. The major reason cited for lack of adequacy was that undergraduate genetics courses were not practical. Only 17 respondents stated that they were never approached for information on genetics or animal breeding, while 76 were approached more than 20 times annually for information. Eighty-three respondents claimed to deal with more than 20 cases annually that required some knowledge of genetics. The results of the questionnaire highlight the importance of genetics instruction in undergraduate veterinary education. The questionnaire responses also provide insight into how working veterinarians consider that courses in genetics could be improved.