The SARS-CoV-2 Pseudoviral Particles are replication-deficient Maloneymurine leukemia virus (MLV or MuLV) pseudotyped with the SARS-CoV-2 spike protein of the Delta variant (Indian B.1.617.2) (also named 20A/S:478K, VUI-21APR-02) (GISAID accession # EPI_ISL_2020954). MLV-based virus system is a better choice than HIV-based lentivirus system for making pseudoviral particles in regards of lab safety and product quality. Gag-Pol is the only component from MLV.