碩士 / 國立中興大學 / 獸醫病理學研究所 / 93 / Abstract
High density culture condition of Litopenaeus vannamei aquaculture always results in serious outbreaks of various diseases such as Taura syndrome virus (TSV) accompanied with Vibrio vulnificus co-infection in Taiwan. TSV can affect all growing stages of shrimps with high mortality and cause tremendous economic loss especially with secondary bacterial infection. The aims of this study are to develop an inoculation model to study the pathogenesis of TSV in L. vannamei and also to evaluate the influence of haemocytes phagocytosis against V. vulnificus if shrimps previously infected with TSV. Moreover, semi-quantification by RT-PCR and Alpha-Image 2200 software are applied to determine the challenge dose of TSV. In addition, the clinical findings, mortality, and histopathology are also utilized to evaluate the status after TSV inoculation.
The shrimps from natural TSV affected, the experimentaly oral inoculated for 7 consecutive days, and control group was selected to compare haemocytes phagocytosis against V. vulnificus in vivo. The hemolymph were collected 3 hours after intramuscularly injected with 0.5 ml of latex beads (1×107∕ml) or Vibrio vulnificus (1×107cfu∕ml) labeled with FITC at the second abdominal segment of experimental shrimps. The phagocytic activity of haemocytes was further analyzed by measuing the level of fluorescence using Flow cytometry. The results showed that there were no significant differences of phagocytic activity against pathogenic V. vulnificus between naturaly infected TSV group (42.28 ± 7.63) and TSV oraly infected group (35.86 ± 2.53) according to the average of fluorescence value. However, there were apparent differences between control group (91.15 ± 22.27) and both TSV affected groups. However, phagocytic activities of haemocyts to latex beads in naturally infected (2126.78 ± 292.12) and TSV challenged group (121.52 ± 36.71) were higher than control groups (56.51 ± 15.25). The highest peak (4/20) of mortality was noticed at the fourth to fifth day and the accumulated mortality could reach 60% (12/20) after TSV inoculated orally. Furthermore, TSV could be detected with RT-PCR from the gill tissue (100%, 20/20) and swimming feet (40%, 2/5) of affected shrimps. Histopathological examination also indicated that massive to multifocal to diffuse necrotic lesions were noticed in shell surface (4/12), subcutaneous tissue of appendant limbs (3/12), gill (3/12), and hepato-pancreatic glands (2/12).
The experimental results suggest that TSV can be transmitted horizontally, and impair the ability of haemocyts phagocytosis against pathogenic V. vulnificus in Litopenaeus vanname. This phenomenon may elucidate that the TSV affected shrimps are always accompanied with secondary bacterial infection.
| Identifer | oai:union.ndltd.org:TW/093NCHU0628009 |
| Date | January 2005 |
| Creators | CHEN WE FU, 陳韋富 |
| Contributors | 簡茂盛 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 70 |
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