Quantitative detection of Vibrio cholera toxin by real-time and dynamic cytotoxicity monitoring.
We report here the quantitative detection of Vibrio cholerae toxin (CT) in isolates and stool specimens by dynamic monitoring of the full course of CT-mediated cytotoxicity in a real-time cell analysis (RTCA) system. Four cell lines, including Y-1 mouse adrenal tumor cells, Chinese hamster ovary (CHO) cells, small intestine epithelial (FHs74Int) cells, and mouse adrenal gland (PC12-Adh) cells, were evaluated for their suitability for CT-induced cytotoxicity testing. Among them, the Y-1 line was demonstrated to be the most sensitive for CT-mediated cytotoxicity, with limits of detection of 7.0 pg/ml for purified CT and 0.11 ng/ml for spiked CT in pooled negative stool specimens. No CT-mediated cytotoxicity was observed for nontoxigenic V. cholerae, non-V. cholerae species, or non-V. cholerae enterotoxins. The CT-RTCA assay was further validated with 100 stool specimens consecutively collected from patients with diarrhea and 200 V. cholerae isolates recovered from patients and the environment, in comparison to a reference using three detection methods. The CT-RTCA assay had sensitivities and specificities of 97.5% and 100.0%, respectively, for V. cholerae isolates and 90.0% and 97.2% for stool specimens. For stool specimens spiked with CT concentrations ranging from 3.5 pg/ml to 1.8 ng/ml, the inoculation-to-detection time was 1.12 ± 0.38 h, and the values were inversely correlated with CT concentrations (ρ = -1; P = 0.01). The results indicate that the CT-RTCA assay with the Y-1 cell line provides a rapid and sensitive tool for the quantitative detection of CT activities in clinical specimens.
Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China.
Dazhi
D
Jin
Yun
Y
Luo
Min
M
Zheng
Haijing
H
Li
Jing
J
Zhang
Melinda
M
Stampfl
Xiao
X
Xu
Gangqiang
G
Ding
Yanjun
Y
Zhang
Yi-Wei
YW
Tang
D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002771:Cholera / Q000175:diagnosis*; D002772:Cholera Toxin / Q000032:analysis* / Q000633:toxicity*; D006224:Cricetinae; D003412:Cricetulus; D003967:Diarrhea / Q000175:diagnosis; D006801:Humans; D051379:Mice; D012680:Sensitivity and Specificity; D014734:Vibrio cholerae / Q000378:metabolism*
D002772:Cholera Toxin