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Updated: Aug 17, 2026

Development of an IFN-γ ELISpot Assay to Assess Varicella-Zoster Virus-specific Cell-mediated Immunity Following Umbilical Cord Blood Transplantation
Published on: July 9, 2014
Enhancement of varicella-zoster virus plaquing efficiency with an agarose overlay medium
D L Krah1, T L Schofield, P J Provost
1Department of Virus and Cell Biology, Merck Sharp and Dohme Research Laboratories, West Point, PA 19486.
Abstract:
The infectivity titers of varicella-zoster virus (VZV) are routinely estimated by plaque production in cell culture. In this report, we show that plaque counts for VZV (strain Oka/Merck), in MRC-5 cell cultures, are significantly enhanced (54% average enhancement) by the use of an agarose overlay medium, as compared to a fluid overlay medium. Evidence also is presented that less variability (P less than 0.05) in plaque counts occurs with the use of an agarose overlay medium.

