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1
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Speaker(s)：
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Hsu, Wei-Cheng
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Topic
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The Toxicologic Pathology of Aflatoxin B1 in One-day-old Brown Tsaiya after Exposure to Contaminated Commercial Dog Food
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Abstract
Aflatoxins are produced by different species ofAspergillus, and particularly of flavus and parasiticus. There are four major types of aflatoxins: B1, B2, G1, and G2. Aflatoxin B1 is considered the most toxic.High-level aflatoxin exposure produces an acute hepatic necrosis, resulting later in An outbreak of foodborne aflatoxicosis in dogs in Taiwan from late 2008 through early 2009 brought this issue to the forefront of public attention. The purpose of this study was to investigate clinical symptoms and pathogenesis of aflatoxicosis in animals. In the experiment, a total of twenty one-day-old ducklings (Brown Tsaiyas) were fed with aflatoxinB1 contaminated dog food (133 ppb) for 14 days in the experiment group. In the control group, two one-day-old ducklings were fed with aflatoxin B1-free duck food. During the experiment, euthanasia was performed on one duckling per day for serum enzyme activity test and pathology examination. Depression, poor appetite and weight-loss could be found in the aflatoxin-affected ducks on day 9 after exposure (AE). Hepatic enzymes including lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) exhibited no significant differences between the experiment and control group. Gross pathology showed enlarged and pale of liver on day 6 AE; ascites and prominent connective tissue septa surrounding hepatic lobules were found on day 10 AE; liver was firm by palpation on day 14 AE. Histopathology examination on day 4 AE showed specific lesion of toxic hepatopathy; on day 14 AE, a diffuse nodular regeneration of the liver was detected. Our results reveal that ducks fed with aflatoxin B1 133 ppb would lead to sub-acute toxicity of liver and growth retardation, while pathological examination can assist in early detection of disease, even though the serum biochemical tests are not sensitive. This study provides important implications to clinical diagnosis of aflatoxicosis in the future.cirrhosis, and carcinoma of the liver.
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2
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Speaker(s)：
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Hsu, Ai-Ping
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Topic
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The Development of a Bovine Ephemeral Fever G protein Subunit Vaccine
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Abstract
Bovine ephemeral fever (BEF) caused by bovine ephemeral fever virus (BEFV) is an arthropod-borne disease. In Taiwan, the first outbreak of BEF was in 1967, and since then it has occurred every three to six years. The febrile disease causes serious economic damage in dairy and grazing industries through reduced milk production and rising cull rate. As currently available killed vaccines produced by cell culture could not gain high virus titers, it is costly to produced these vaccines. According to several former studies, the glycoprotein G (G protein) of BEFV possessed excellent immunogenicity and elicited neutralizing antibodies against BEFV. Furthermore, the recombinant G protein produced by baculovirus expression vector system (BEVS) retained its original antigenicity. The aim of our study was to produce efficacious and cost effective BEFV G protein subunit vaccines through the baculovirus system. The nucleic acid fragments of G protein used for this study came from a field isolated BEFV strain in Taiwan in 2007. They were amplified and a large scale of recombinant G proteins was produced by means of the baculovirus expression system. As a result, both G proteins in the form of full length and transmembrane domain deleted form were expressed. The G protein of full length exhibited fusogenic activities, a reaction similar to that reported in previous studies. It reacted to polyclonal antiserum better in western blots analysis and immunofluorescence assay than the deleted form. For future studies, the immunogenicity of recombinant G proteins will be further evaluated on mice and the one showing the best reaction will be selected for vaccination studies in cattle.
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3
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Speaker(s)：
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Tsai, Jia-Cheng
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Topic
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An Investigation of Fish Disease in 2009
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Abstract
Betanodavirus (two single-stranded, positive–sense RNA virus) and iridovirus (double-stranded DNA virus) are the main causes for serious viral diseases in Asian aquaculture. Both viruses have been reported as causing a serious disease of larval and juvenile marine fish that occurs almost worldwide. To date, the diseases have been reported in at least 30 fish species. The vertical transmission is a major infection route in betanodavirus, and clinical signs of betanodavirus infection are characterized by a variety of neurological abnormalities, such as spiral, whirling erratic swimming or belly-up at rest on juvenile to young stages fish; however, these are usually slight and insignificant signs on adult fish. The principal mode of transmission of iridovirus is horizontal via water. Affected fish become lethargic and inactive. Proliferation of virus in the hematopoietic organ and spleen results in severe anemia and enlargement of spleen.
Ping-Tung County is the second biggest net-cage aquaculture and also the fifth largest fish farming production county in Taiwan. In 2009, we collected 228 fish organ cases and 39 bacterial identification samples from farmers of Ping-Tung County. Molecular biological technique, virus isolation, and bacterial identification were applied for the study, and the results obtained are as follows: betanodavirus and iridovirus detected by RT-PCR or PCR; TGIV (grouper iridovirus of Taiwan) had the highest positive rate (21.1%); RSIV (red sea bream iridovirus) was 10.5%. ISKNV (infectious and kidney necrosis virus) and betanodavirus positive rate were both 10.1%. The supernatants of tissue homogenates were co-cultured with cell line 7-GK and E-11; 21 isolates of TGIV and 10 isolates of betanodavirus were obtained. As to the bacterial identification, Streptococcus spp. (32%) and Nocardia seriolae (21%) were the major pathogens found in collected samples.
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