Abstract:Lentiviral vector is an important gene transduction tool for gene therapy and plays an a crucial role in the treatment of hematologic tumors by chimeric antigen receptor (CAR) T cells. The prerequisite for the preparation of high quality CAR-T cells is to obtain lentivirus with high titer by concentration, and ultracentrifugation and ultrafiltration are two main methods for virus enrichment. In order to determine the efficiency of ultracentrifugation and ultrafiltration for virus concentration, and their effect on virus activity in the preparation of research-grade CAR-T, two lentivirus plasmids (GFP and CD19 CAR(CAR19)-mCherry) were selected to package lentivirus, then titer and recovery rate were compared. The results showed that the titer of virus produced by ultrafiltration reached 1011 TU/mL, which was significantly higher than that by ultracentrifugation (P<0.05), and the higher recovery efficiency was also obtained by ultrafiltration. These results can provide direct theoretical reference for the lentivirus concentration method to support the preparation of laboratory-grade CAR-T, and are helpful for the rapid development of CAR-T basic research.