Factors influencing the assay of inoue-melnick virus

Abstract We describe factors influencing the assay of Inoue-Melnick virus (IMV) and practical comments for its assay. MRC-5 cells at a population doubling level (PDL) of more than 32 were more sensitive than younger cells for demonstrating cytopathic effect (CPE) of the virus. The PDL of MRC-5 cells also influenced the virus yield, particularly when the amount of viral inoculum was small. Cells at younger PDL produced less virus. The appearance of CPE and the virus yield were inhibited by increasing the concentration of NaHCO 3 to 0.14% in the maintenance medium. The release of the virus into the medium was also inhibited as NaHCO 3 was increased.