Enterobacter cloacae associated with mass mortality in zoea of giant freshwater prawns Macrobrachium rosenbergii and control with specific chicken egg yolk immunoglobulins (IgY)
Enterobacter cloacae associated with mass mortality in zoea of giant freshwater prawns Macrobrachium rosenbergii and control with specific chicken egg yolk immunoglobulins (IgY)
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DOI：
10.1016/j.aquaculture.2018.11.050
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发表时间：
2019-02-25
期刊：
影响因子：
4.5
通讯作者：
Zhang, Xiaojun
中科院分区：
文献类型：
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作者：
Gao, Xiaojian;Zhang, Honghua;Zhang, Xiaojun
养殖的M. 2017年4月，高邮市不同养殖场发生罗氏沼虾。从病蚤状幼体中分离到的菌株中，XL 3 -1对蚤状幼体和幼虫具有致病性。在毒力试验中，rosenberlavirus的LD 50值分别为3.2 x 10（6）CFU/mL和3.5 x 10（6）CFU/mL。通过生化特征和分子生物学手段鉴定XL 3 -1为阴沟肠杆菌。PCR检测毒力相关基因结果表明，XL 3 -1为irp 2、fhuA、sodB、sltA、flaD和OmpX阳性。耐药试验结果表明，该菌株对喹诺酮类药物敏感，对头孢菌素类和青霉素类耐药。本研究还研究了特异性鸡卵黄抗体（IgY）对大肠杆菌的保护作用。感染根癌病菌的M.罗森伯托。对E. ELISA法测得特异性IgY的效价为1：2（13）。M.用特异性蛋黄粉处理后的罗氏沼虾，其成活率可达67%。Clobacillus infection，而M.用非特异性蛋黄粉处理和不加蛋黄粉处理的罗氏沼虾成活率分别为20%和17%。同时，肝胰腺中的细菌负荷在M.特异性蛋黄粉处理的月季花比非特异性蛋黄粉处理的月季花更好。阐明了大肠杆菌的毒力特性和耐药性。为利用特异性IgY防治该病提供了策略。
Outbreaks of mass mortality among cultured zoea of M. rosenbergii occurred in different hatcheries of Gaoyou country of China in April 2017. Of the isolates obtained from the diseased zoea, XL3-1 was pathogenic to the zoea and postlarva of M. rosenbergii in the virulence test, with a LD50 value 3.2 x 10(6) CFU/mL and 3.5 x 10(6) CFU/mL, respectively. XL3-1 was identified as Enterobacter cloacae by biochemical characteristics and molecular tools. Detection of virulence-associated genes by PCR indicated that XL3-1 was positive for irp2, fhuA, sodB, sltA, flaD and OmpX. According to the antibiotic resistant assay, the isolate was sensitive to quinolones, while they were resistant to cephalosporins and penicillins. This study also investigated the protection of specific chicken egg yolk antibodies (IgY) in E. doacae-infected M. rosenbergii. The highest titer against E. cloacae of the obtained specific IgY by ELISA was 1: 2(13). M. rosenbergii treated with specific egg yolk powder could achieve the survival rate of 67% after E. cloacae infection, while M. rosenbergii treated with non-specific egg yolk powder or no egg yolk powder could achieve survival rates of 20% and 17%, respectively. As well, the bacterial burden in hepatopancreas was significantly lower in M. rosenbergii treated with specific egg yolk powder than those treated with non-specific egg yolk powder. This study clarified the virulence characteristics and antibiotic resistance of E. cloacae, and provided a strategy to control the disease by using specific IgY.