Transposon mutagenesis screen identifies MHC class II transactivator (CIITA) as an inducer of cellular resistance to Ebola virus and SARS Coronavirus

U2OS cells were co-transfected with PiggyBac (PB) transposon plasmid pPB-SB-CMV-puro-SD3 and the transposase p-hyPBASE. The modified PiggyBac (PB) transposon, which has a constitutively active CMV promoter which can stimulate or disrupt expression of neighboring genes, depending on insertional orientation. For each library, between 107-108 cells were transfected, cultured with the addition of 2 µg/ml puromycin for one week to select cells that had incorporated the transposon, and then used for screens of virus resistance with minimal further expansion. Mutagenized cells were challenged with replication-competent recombinant EboGP-VSV at MOI of 1 or 10 and propagated for up to 3 weeks with regular media changes to select virus-resistant colonies. After virus resistant cells were selected, genomic DNA (gDNA) was isolated from 5-10 X 106 cells and transposon insertion sites were mapped using high throughput sequencing. Eight individual libraries were created and were combined for common insertion site analysis (CIS).