The "pseudo" in "pseudovirus" mainly refers to the modification of the nucleic acid within the viral particle, which results in the loss of its replication ability. As a result, pseudoviruses are non-pathogenic and significantly safer than "real" viruses. Typically, experiments involving real viruses must be conducted in biosafety level 3 (BSL-3) or higher laboratories, whereas pseudovirus experiments can be safely carried out in biosafety level 2 (BSL-2) laboratories.
Pseudoviruses offer excellent safety and have advantages such as broad host range and efficient transfection of non-dividing (quiescent) cells without dependence on the cell cycle. Therefore, they play an important role in studying the interactions between viruses and host cells, evaluating neutralizing antibody titers, and advancing gene therapy. Pseudoviruses are emerging as novel and safe experimental tools, serving as powerful assets in vaccine and drug development industries.