Full-Text Search:
Home|About CNKI|User Service|中文
Add to Favorite Get Latest Update

Preliminary study on the prevention and treatment effect of phage against ETEC infection in mice

HU Le-yu;SONG Peng;CUI Jia-qi;ZOU Ling;LIU Wen-hua;ZHANG Can;HAN Xian-jie;REN Hui-ying;College of Veterinary Medicine, Qingdao Agricultural University;  
To study the prevention and treatment of phage against enterotoxigenic Escherichia coli (ETEC) infection in mice,the titer of phage DS2 was determined by double agar overlay plaque assay,and the in vitro lysis effect of phage DS2 on E.coli K88,K99 and 987p causing piglet diarrhea was detected by double agar overlay plaque assay.The results showed that the phage DS2 had a titer of 6.9×10~9pfu/mL and could lyse the three strains of ETEC.The efficacy of phage against ETEC infection in vivo was further evaluated by mouse experiment;the mice were inoculated with 0.2mL phage per mouse by intraperitoneal injection of 2×10~8pfu/mouse (high-dose group) and 2×10~7pfu/mouse (low-dose group).After 1 hour,mice in each group were intraperitoneally injected with 0.2mL of piglet diarrhea E.coli mixture K88,K99 and 987p with a dose of 3×10~8cfu/mouse.The livers of mice in each group were collected aseptically at 12,24 and 48 hours after infection,and the amount of bacteria in the livers of mice in each group was examined by plate count method.The phage content in the livers of mice in each group was assesssed by double agar overlay plaque assay.Twenty-four hours after infection,serum IL-1β levels of mice in each group were detected by ELISA kit.Forty-eight hours after infection,plasma endotoxin content of mice in each group was determined by limulus endotoxin test kit.Compared with the control group inoculated with LB broth,the bacterial load and phage content in the liver of mice in the highdose and low-dose groups increased or decreased at different time after infection,but there was no significant difference with control group or between the two groups (P0.05).As the infection time prolonged,the content of phage in liver of mice in highdose and low-dose groups decreased,and the content of phage in liver of mice in low-dose group was significantly higher (24 hours after infection)(P0.01) or higher (48 hours after infection) than high-dose group.The results of IL-1β and endotoxin detection showed that compared with the control group,the levels of IL-1β in serum of mice in high-dose and low-dose groups were significantly decreased (P0.05) or decreased,but the plasma endotoxin content in high-dose and low-dose groups increased or significantly increased (P0.05).Sixty mice were divided into groups and treated according to the above experiment.The morbidity and mortality of each group were observed and recorded within 72 hours after infection,and the average body condition score of each group at different times after infection was calculated.The results showed that the body condition score of mice in control group decreased to less than 25 points after nearly 24 hours of infection,and the body condition score of mice in high-dose and low-dose groups decreased to more than 70 and 90 points after 24 hours of infection.The survival rate of high-dose group,lowdose group and control group mice was 65%,95% and 15%,respectively.These results suggest that DS2 phage can effectively prevent and treat ETEC infection in vitro and in vivo,and the efficacy of low-dose DS2 phage is generally better than that of highdose phage.This study will potentially provide a new way for the prevention and treatment of piglet colibacillosis.
Download(CAJ format) Download(PDF format)
CAJViewer7.0 supports all the CNKI file formats; AdobeReader only supports the PDF format.
©CNKI All Rights Reserved