拟态弧菌感染黄颡鱼的动态病理损伤及病原分布研究

摘要

In this study,yellow catfish(Pelteobagrus fulvidraco)were infected by immersion challenge with Vibrio mimicus(1.0×106 CFU·mL-1).The challenged fish were sampled at 0,4th,8th,16th,24th,36th,48th,60th and 72nd hour post infection to detect the histopathological changes and distribution of bacteria.Pathologic results show that skin,muscle,gills and intestines were the first to produce pathologic changes,and skin and muscle were most seriously damaged.Degeneration of the epidermis,edema of gill epithelium and intestinal mucous membrane were observed at 16th hour post infection.Then,necrosis and fallen off of epidermis,serious hemorrhage of dermis and necrosis of muscle fibers,hemorrhage of gills and focal necrosis of intestines were observed from 24th hour to 48th hour;during 48th hour to 72nd hour,skin and muscle fibers formed ulcer lesions and gills showed hemorrhages and focal necrosis.Besides,liver,spleen,kidney and heart showed different degrees of pathological changes after 36-hour post infection,including congestion,hemorrhage,degeneration and focal necrosis.Real-time PCR results show that V.mimicusis were detected in gills,intestines and muscle initially at 4th hour post infection and the quantity of bacteria were 1.3×102CFU·mg-1 in intestines,2.6×102 CFU·mg-1 in gills and 4.7×102 CFU·mg-1 in muscle,respectively.The quantity of bacterial in gills and muscle increased at the rest of time and then reached a peak at 72nd hour,about 4.7×107 CFU·mg-1;After 24 h,V.mimicusis were detected in liver,spleen and heart,and the range of quantity was from 1.9×10 CFU·mg-1 to 4.7×102 CFU·mg-1.Results suggest that gill,intestine,muscle are first invasion sites of V.mimicus,and most of the internal organs can be invaded.%以1.0×106 CFU·mL-1拟态弧菌(Vibrio mimicus)浸浴感染黄颡鱼(Pelteobagrus fulvidraco),于第0、第4、第8、第16、第24、第36、第48、第60、第72小时剖杀取样,研究病理损伤及病原菌的体内动态分布.结果显示,皮肤肌肉、鳃、肠道出现病变最早,其中皮肤肌肉损伤最严重.第16小时表皮变性、坏死,鳃上皮肿胀,肠绒毛水肿;第24～第48小时表皮坏死、脱落,真皮严重出血,肌纤维变性、坏死,鳃出血,上皮局部坏死,肠上皮变性与灶性坏死;第48～第72小时皮肤肌肉坏死更严重,形成溃疡灶,鳃灶性坏死.肾、肝、脾与心36 h后相继出现不同程度的淤血、出血,变性和灶性坏死.qPCR检测发现,第4小时即在鳃、肠、皮肤肌肉检出病菌,细菌含量分别为1.3×102 CFU·mg-1、2.6×102 CFU·mg-1、4.7×102 CFU·mg-1;鳃与皮肤肌肉中菌量随时间延长而增加,第72小时皮肤肌肉中菌量达到4.5×107 CFU·mg-1;第24小时后相继在肾、肝、脾、心检出病菌,菌量介于1.9×10～4.7×102 CFU·mg-1之间.结果表明皮肤、鳃和肠道是病菌的入侵位点,并在体内多组织、器官分布.