Improved Zika virus plaque assay using Vero/TMPRSS2 cell line

ABSTRACT Plaque assay is the gold standard for the quantification of viable cytopathic viruses like Zika virus (ZIKV). Some strains of ZIKV produce plaques that are very difficult to accurately visualize and count on the commonly used Vero cell line. From data generated in our lab, we became curious if Vero/TMPRSS2 cells may be a better alternative, therefore we compared the plaque forming units (PFU) of two strains of ZIKV on Vero/TMPRSS2 cells to those produced by Vero cells. We also compared the virus stock titer generated on Vero/TMPRSS2 cells to that generated by the Vero cell line. Although Vero cells generated higher quantity of ZIKV stocks, Vero/TMPRSS2 cells produced plaques with significantly improved morphology and visibility and may therefore be a better alternative to use for performing plaque assays for strains of ZIKV that are more difficult to titer on regular Vero cells.