| 摘要: |
| 采用硫酸铵盐析法提取海豚链球菌DGX07菌株的胞外产物(ECPs), 通过平板扩散法对其主要酶成分进行初步研究, 对酶热稳定和溶血活性进行测定; 并对腹腔注射接种海豚链球菌(S. iniae)胞外产物的斑点叉尾进行组织病理学观察。结果显示, 菌株胞外产物具有蛋白酶、DNA酶和溶血活性; DNA 酶表现出一定的热稳定性, 而蛋白酶和溶血活性在80℃或100℃作用10min均丧失; 胞外产物对人(O型)、兔、斑点叉尾、草鱼、鲤鱼、鲫鱼、黄颡鱼和长吻的红细胞均表现出不同程度的溶血活性; 人工感染试验显示, 0.222mg/ml 的S. iniae ECPs对斑点叉尾具有明显的致病性, 死亡率达100%; 临床特点表现为: 游动缓慢、体表褪色、鳍条边缘褪色, 内脏器官肿胀并伴有腹水; 组织学病变主要表现为全身性多组织、器官炎性水肿, 伴有组织内出血, 实质细胞变性和坏死, 尤以肝胰脏、脾脏、肾脏、肠道和心脏的损伤最为严重。试验结果表明海豚链球菌胞外产物含有多种毒力因子, 与该菌的致病性密切相关。 |
| 关键词: 斑点叉尾鮰 海豚链球菌 胞外产物 酶活性 致病性 |
| DOI：10.11693/hyhz201302009009 |
| 分类号: |
| 基金项目:教育部“长江学者和创新团队发展计划”创新团队项目, IRT0848 号 |
附件 |
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| PATHOGENICITY ON CHANNEL CATFISH ICTALURUS PUNCTATUS BY EXTRACELLULAR PRODUCTS OF STREPTOCOCCUS INIAE |
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CHEN De-Fang1, WANG Kai-Yu2,3, WANG Kai-Yu2, GENG Yi2,3, HUANG Ling-Yuan2, HU Di2, JING Jian-Fei2
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1.College of Animal Science and Technology, Sichuan Agricultural University;2.College of Veterinary Medicine, Sichuan Agricultural University;3.Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University
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| Abstract: |
| Extracellular products (ECPs) were extracted from strain DGX07 of Streptococcus iniae by ammonium sulfate precipitation method. The main enzyme ingredients were preliminary assayed by plate diffusion method. Enzyme thermal stability and hemolytic activity were performed. To observe the histopathologic changes, ECPs was challenged with channel catfish Ictalurus punctatus by intraperitoneal (i.p.) route. The experiment results indicate that ECPs were found to exhibit hemolytic activity and certain properties of protease and DNase. The protease and hemolytic activity were lost at 80℃or 100℃in 10min, while the DNase showed certain thermal stability. ECPs showed discrepantly hemolytic activities when acted on the red cells of human (type O), rabbit, channel catfish, grass carp, carp, crucian carp, yellow cat-fish, and longsnout catfish. ECPs were pathogenic to channel catfish at a concentration of 0.222mg/ml, and the mortality reached to 100% when injected under this dose. Clinical symptoms of challengedfish included slow-swimming, body sur-face and fin edge fading, and swelling visceral organs with ascites. Histological lesions included inflammatory edema of systemic multiple tissue and organ, organization internal bleeding, degeneration and necrosis of parenchyma cells, damage especially in the liver, spleen, kidney, intestine and heart. The results highlight that S. iniaeextracellular products contained a variety of virulence factors, which were closely related to the pathogenicity of the bacteria. |
| Key words: channel catfish Ictalurus punctatus Streptococcus iniae extracellular products enzyme activity pathogenicity |
