Comparison of the plaque assay and 50% tissue culture infectious dose assay as methods for measuring filovirus infectivity

Abstract

Two common methods of quantifying filovirus infectivity, a plaque assay and 50% cell culture infectious dose (TCID50) endpoint dilution assay, were compared. The two assays were performed side by side using the same virus stock sample to determine the correlation between the results of the two assays. The TCID50 assay appeared to be more sensitive but slightly more variable, and there was a tenfold difference in the numerical results of these methods of enumeration. The advantages and disadvantages of both assays are discussed. Both methods are useful and practicable in filovirus research, and this comparison will be hugely beneficial to the filovirus research community as it seeks to become more united. Further work in this area should be performed to ensure consistency in filovirus research.

Keywords: 50% tissue culture infectious dose; ACDP; Advisory Committee for Dangerous Pathogens; Assays; BSL; CPE; Counting; FBS; FCS; Filoviruses; PD; PFU; Plaque; TCID(50); Tissue culture infectious dose; biosafety level; cytopathic effects; fetal bovine serum; fetal calf serum; plaque forming unit; proportional distance.