Observations on the growth and plaque assay of BK virus in cultured human and monkey cells

Although human embryo kidney (HEK), muscle (HEM) and lung (HEL) cells are capable of supporting the replication of BK virus (BKV) through passage levels 9, 12 and 12 respectively, only third, fourth and fifth passage level HEK cells were found to be satisfactory for the plaque assay of the virus. BSC-I and VERO cells can also be used for the plaque assay of BKV. However, in HEK cells plaques can be visualized in 20 days (compared to 28 days in BSC-I cells), and since in VERO cells the plaques are poorly defined and the titre about I log10 lower than in either HEK or BSC-I cells, HEK cells were the ones chosen for use.