Infectivity of pestivirus following persistence of acute infection     

Margaret E. Collins  Judith Heaney  Carole J. Thomas  Joe Brownlie 《Veterinary microbiology》2009,138(3-4):289-296

Bovine viral diarrhoea virus (BVDV) is an endemic pathogen worldwide and eradication strategies focus on the identification and removal of persistently infected (PI) animals arising after in utero infection. Despite this, acute infections with BVDV can persist for months or years after the removal of the PI source despite repeated screening for PIs and tight biosecurity measures. Recent evidence for a prolonged duration of viraemia in the testicles of bulls following acute BVDV infection suggests the possibility of a form of chronic persistence that may more closely resemble the persistence strategies of hepatitis C virus (HCV). To investigate the potential for virus transmission from infected and recovered cattle to virus naïve hosts we established an acute infection of 5 BVDV-naïve calves and monitored animals over 129 days. Infectious BVDV was detected in white blood cells between days 3 and 7 post-challenge. The animals seroconverted by day 21 post-infection and subsequently were apparently immune and free from infectious virus and viral antigen.Animals were further monitored and purified white blood cells were stimulated in vitro with phytohaemagglutinin A (PHA) during which time BVDV RNA was detected intermittently.Ninety-eight days following challenge, blood was transferred from these apparently virus-free and actively immune animals to a further group of 5 BVDV-naïve calves and transmission of infection was achieved. This indicates that BVDV-infected, recovered and immune animals have the potential to remain infectious for BVDV-naïve cohorts for longer than previously demonstrated.  相似文献   

Experimental canine leptospirosis caused by Leptospira interrogans serovars pomona and bratislava     

Greenlee JJ  Alt DP  Bolin CA  Zuerner RL  Andreasen CB 《American journal of veterinary research》2005,66(10):1816-1822

OBJECTIVE: To evaluate gross, histopathologic, and serum biochemical findings caused by Leptospira interrogans serovars pomona and bratislava inoculated in dogs. ANIMALS: Twenty-seven 8-week-old female Beagles. PROCEDURE: Dogs were randomly assigned to challenge or control groups. Challenge groups were conjunctivally inoculated on 3 successive days with 5 x 10(7) L interrogans serovar pomona (n = 12) or serovar bratislava (11). Clinical signs were recorded throughout the experiment, and clinical pathology assays, bacteriologic culture, and necropsies (6 or 7 dogs necropsied at each time point) were done on postinoculation day (PID) 7, 10, 14, and 20. RESULTS: Infection could not be confirmed in any serovar bratislava-inoculated dog, and control dogs remained healthy throughout the experiment. Positive culture and fluorescent antibody test results were confirmed in 11 of 12 serovar pomona-inoculated dogs. Fever and lethargy starting at PID 7 were the most common clinical signs in serovar pomona-infected dogs. On day 10, gross lesions included multifocal renal and pulmonary hemorrhage and perirenal edema. Serovar pomona-inoculated dogs had histopathologic lesions including hepatitis, interstitial nephritis, and pneumonia at PID 7, 10, 14, and 20. Increases in BUN, anion gap, and bilirubin concentration occurred on PID 10, 14, and 20. Platelet counts in dogs with positive results of bacteriologic culture were decreased from baseline values on PID 10, 12, and 14. CONCLUSIONS AND CLINICAL RELEVANCE: Conjunctival inoculation with L interrogans serovar pomona resulted in a high rate of infection with concomitant hemorrhagic and inflammatory lesions of the kidneys, liver, and lungs.  相似文献   

Microarray analysis of Haemophilus parasuis gene expression under in vitro growth conditions mimicking the in vivo environment     

Melnikow E  Dornan S  Sargent C  Duszenko M  Evans G  Gunkel N  Selzer PM  Ullrich HJ 《Veterinary microbiology》2005,110(3-4):255-263

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Clinical and pathologic comparison of acute leptospirosis in dogs caused by two strains of Leptospira kirschneri serovar grippotyphosa     

Greenlee JJ  Bolin CA  Alt DP  Cheville NF  Andreasen CB 《American journal of veterinary research》2004,65(8):1100-1107

OBJECTIVE: To develop a method for inducing acute leptospirosis in dogs. ANIMALS: 31 nine-week-old female Beagles. PROCEDURE: Beagles were randomly assigned to 2 inoculation groups or a control group. Dogs were inoculated on 3 successive days by conjunctival instillation of 5 x 10(7) cells of Leptospira kirschneri serovar grippotyphosa strain 82 (12 dogs) or strain RM 52 (14 dogs). Control dogs (n = 5) were similarly inoculated with sterile leptospiral culture media. Clinical signs, clinicopathologic variables, anti-leptospiral antibody titers, and evidence of leptospires in tissues and body fluids were evaluated. Dogs were euthanatized and necropsied on days 7, 14, 22, or 28 after inoculation or as required because of severe illness. RESULTS: Clinical signs in infected dogs included conjunctivitis, lethargy, diarrhea, dehydration, vomiting, and icterus. Consistent clinicopathologic alterations included azotemia, hyperphosphatemia, increased anion gap, hyperbilirubinemia, and an increase in alkaline phosphatase activity. Leptospires were cultured from the kidneys (11/12), urine (6/9), aqueous humor (9/12), blood (12/12), and liver (12/12) of dogs inoculated with strain 82. Only 3 of 14 dogs became infected after inoculation with strain RM 52. Histopathologic lesions in infected dogs included interstitial nephritis, renal tubular degeneration and necrosis, pulmonary hemorrhage, and hepatic edema and perivasculitis. CONCLUSIONS AND CLINICAL RELEVANCE: Conjunctival exposure to L kirschneri serovar grippotyphosa strain 82 resulted in acute leptospirosis in all inoculated dogs, but only 3 of 14 dogs inoculated with strain RM 52 became infected. This method of infection by serovar grippotyphosa can be used to study the pathogenesis and prevention of leptospirosis in dogs.  相似文献   

Comparison of commercial enzyme-linked immunosorbent assays and agar gel immunodiffusion tests for the serodiagnosis of equine infectious anemia          下载免费PDF全文

Julie Paré  Carole Simard 《Canadian journal of veterinary research》2004,68(4):254-258

The purpose of this study was to estimate the performance characteristics (accuracy, detection limit, and precision) of commercially available enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) kits in comparison with a reference AGID kit for the detection of equine infectious anemia (EIA) antibodies in horses for regulatory use in Canada. A total of 285 positive and 315 negative samples by the reference AGID were tested blindly on 2 other AGID and 4 ELISA kits. Commercially available AGID kits for the serodiagnosis of EIA were found equivalent. The 3 ELISAs directed against antibodies to the p26 core protein also performed relatively well in comparison with the reference AGID, with excellent relative accuracy and acceptable precision. The single ELISA directed against antibodies to the gp45 trans-membrane viral protein yielded a lower relative sensitivity. The performance characteristics of the ELISAs directed against antibodies to p26 are, therefore, adequate to support the implementation of ELISA for regulatory purposes in Canada.  相似文献   

Forecasting monthly catfish (Ictalurus punctatus.) pond bank and feed prices     

Mohammad R. Hasan  Carole R. Engle 《Aquaculture Economics & Management (Blackwell Science)》2019,23(1):86-110

Volatility in catfish pond bank and feed prices lead to profit uncertainty in the catfish industry. Analysis of the factors that affect those prices and development of a forecasting model would provide guidance to catfish farm managers. Error-correction models (ECM) based on cointegrating relationships among variables were specified following development of a single-equation ARIMAX model. Factors identified as those that influence catfish price were: lagged value of catfish, feed and substitute product prices, while those that influenced feed price were: lagged value of feed, corn and soybean prices. ECM estimates implied that fish price adjusts approximately 6% and feed price 22% to the long-run equilibrium in 1?month. The analysis showed that it takes less than 17?months and 5?months to correct for long-run disequilibrium for catfish and feed prices, respectively. The ARIMAX model demonstrated a better fit for both in-sample and out-of-sample forecasting for catfish price and had better out-of-sample predictive ability for feed prices.  相似文献   

The Effect of On-Farm Production of Various Sizes of Stocker Caffish Ictalurus punctatus on Farm Profitability.     

Steeve  Pomerleau Carole R.  Engle 《Journal of the World Aquaculture Society》2005,36(3):291-301

Abstract— The effect of on‐farm production of various sizes of stocker catfish Ictalurus punctatus on farm profitability was compared to profitability of understocking fingerlings directly into multiple‐batch growout production. Vat‐graded catfish averaging 9 × 2 g (10 cm total length) and 27× 8 g (15 cm total length) were stocked into eight 0.1‐ha ponds at 100,000 fingerlingdha. Fish were fed once daily to apparent satiation and harvested 210 d after stocking. There were no significant differences (P < 0.10) in yield, feed conversion ratio (FCR), and survival across treatments. Mean gross yield (× SD) was 9,469 × 852 kg/ha and 8,846 × 2,099 kg/ha; net yield averaged 8,531× 885 and 6,374 × 2,189 kg/ha; FCR averaged 1.8 × 0.1 and 2.4 × 0.7, and survival averaged 38 × 7% and 26 ×11% for the 10‐cm and 15‐m fingerling stocking treatments, respectively. While experimental survival was low, varying survival rates of stockers in the economic analysis did not affect selection of the most profitable stocking strategies. The 15‐cm hgerlings reached a size significantly larger (361× 81 g or 32.8 × 2.2 cm) than the 10‐cm fingerlings (255 × 28 g or 29.6 × 1.4 cm) (P < 0.07). Whole‐farm budgets were developed based on three sizes of farm (65, 130, and 260 ha) and eight production strategies involving the purchase of different sizes of fingerlings for either understocking growout ponds (6,12, or 37‐g fingerlings) or to grow into stockers (114,135, 176, 255, or 361 9). Purchasing 37‐g advanced fingerlings for multiple‐batch production was the most profitable strategy for the three sizes of farm. The second most important profit‐maximizing strategy for larger farm sizes was single‐batch production with 255‐g stockers produced on‐farm, but purchasing 12‐g fingerlings to stock into multiple‐batch production was the second most profitable strategy for the smallest farm. Sensitivity analysis indicated that the results were robust to variation in survival, prices, and other production characteristics. Risk analysis indicated that purchasing 37‐g advanced fingerlings for multiple‐batch production was associated with the lowest levels of economic risk for growout production.  相似文献   

RADIOGRAPHY REVIEW: THE VASCULAR AND BRONCHIAL PATTERNS OF PULMONARY DISEASE     

Carole W.  Myer  DVM  MS 《Veterinary radiology & ultrasound》1980,21(4):156-160

Pulmonary blood vessels account for the majority of radiographically visible structures in normal lung. The vascular pattern of pulmonary disease is characterized by changes in vessel size, shape, contour. Changes in size can be classified as hypo vasularity (decreased size) or hyper vascularity (increased size). The pulmonary arteries and veins may be affected separately or simultaneously. In normal lung, the bronchial structures peripheral to the hilar area are not seen clearly. The bronchial pattern of pulmonary disease is characterized by alteractions in bronchial wall thickness and dinsity, or in bronchial lumen diameter. Mixtures of the four lung patterns, i.e. , alveolar, interstitial, bronchial, and vascular, occur frequently. The lung radiographic pattern in an individual animal depends not only on the disease process present, but also on the stage of the disease during which they are radiographed.  相似文献   

Sustainable Growth of Aquaculture: The Need for Research to Evaluate the Impacts of Regulatory Frameworks          下载免费PDF全文

Carole R. Engle 《Journal of the World Aquaculture Society》2016,47(4):461-463

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Factors Driving Aquaculture Technology Adoption          下载免费PDF全文

Ganesh Kumar  Carole Engle  Craig Tucker 《Journal of the World Aquaculture Society》2018,49(3):447-476

Technology adoption has played a key role in the global development and increase in agricultural productivity. However, the decision to adopt a new technology on farms is complex. While the factors that drive the adoption of new technologies have been well studied in agriculture, less attention has been paid to drivers of technology adoption in aquaculture. Aquacultural technologies have developed and advanced rapidly in recent decades, but not all technologies have been adopted readily by farmers. This review paper summarizes some of the critical factors that influence aquaculture technology adoption decisions such as: (1) method of information transfer, (2) characteristics of the technology, (3) farm characteristics, (4) economic factors, and (5) sociodemographic and institutional factors. Fish farmers have tended to adopt technologies that are perceived to be more advantageous than others in terms of productivity, cost efficiency, and ease of management. Price of aquaculture products and profit expectations from business ventures were key economic factors influencing adoption decisions. Given the wide array of species, production practices, and global nature of aquaculture, the intensity and the extent of adoption of technologies depend on the nature of the industry in which they are adopted and their economic, social, political, and regulatory environments.  相似文献