This researcher was studying demyelinating disease progressive multifocal leukoencephalopathy (PML) is caused by the human polyomavirus, JCPyV, under conditions of prolonged immunosuppression. To identify more information on the mechanism that causes this disease, CRISPR/Cas9 knockout of APMAP in glial cells were performed using lentiviral particles. Cells were drug selected and then seeded on a CellRaft Array. Single cells formed colonies on the CellRaft Array and then were isolated using the AIR System. Clones of interest were identified using western blot analysis and by DNA sequencing through CRISPR deep sequencing service performed at the CCIB DNA core at Massachusetts General Hospital. This researcher was able to identify exogenous expression of APMAP in APMAP knockout cell lines rescued susceptibility to infection suggesting the virus infection of glial cells is dependent on APMAP using CellRaft Arrays.