Pseudovirus is a kind of retrovirus that can integrate the envelope glycoprotein of an infectious virus to form a virus without containing the nucleic acid of the infectious virus, but with the original genome of the retrovirus itself. While studies of immunity to SARS-CoV-2 are limited, pseudotyping viral particles with spike has become an important method to evaluate the SARS-CoV-2 neutralizing antibodies. HIV-based lentiviral particles have recently been used to generate SARS-CoV-2 pseudoviruses. It involves transfecting 293T cells with a lentiviral backbone plasmid encoding luminescent reporter protein (i.g. luciferase), a plasmid expressing spike protein, and plasmids expressing other proteins needed for virion formation. The transfected cells then produce the spike-pseudotyped lentiviral particles which can infect cells that express the ACE2 receptors."