A semi-automated vibriocidal assay for improved measurement of cholera vaccine-induced immune responses

Jae Seung Yang, Hye Jin Kim, Cheol Heui Yun, Seok Seong Kang, Jintaek Im, Hak Sung Kim, Seung Hyun Han

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Vibriocidal antibody assay has been a surrogate standard assay in the evaluation of cholera vaccine efficacy because it has a good correlation with protection. Although the optical density-based vibriocidal assay in a 96-well microtiter-plate format is widely used in clinical trials, it has limitations as vibriocidal titers are altered by incubation time and samples with the same end-point titers could have potentially different vibriocidal kinetics. In the present study, we developed an improved agar-plate assay coupled with an automated colony counting system. Through testing 30 pairs of human sera from vaccinees administered with a cholera vaccine or placebo, these two assays showed good correlations for the vibriocidal titers and fold increases in titers between pre- and post-vaccinated sera as determined by the Pearson correlation coefficient and the Regression coefficient. Notably, the newly-developed semi-automated assay demonstrated that serum samples with the same end-point titers turned out to have distinct vibriocidal kinetics that were not distinguishable by the microtiter-plate assay. The semi-automated assay responded specifically to Vibrio cholerae but not to irrelevant bacteria such as Salmonella typhi and Escherichia coli. These results demonstrate that the semi-automated assay provides better sensitivity, accuracy, and stability of the assay results with minimized efforts than conventional microtiter-plate assay and could provide a useful tool as an in vitro surrogate assay for the evaluation of cholera vaccine efficacy.

Original languageEnglish
Pages (from-to)141-146
Number of pages6
JournalJournal of Microbiological Methods
Volume71
Issue number2
DOIs
StatePublished - Nov 2007

Keywords

  • Cholera vaccine
  • Improved vibriocidal assay
  • Vibrio cholerae

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