Construction and applications of SARS-CoV-2 pseudoviruses: a mini review

Abstract

The ongoing coronavirus disease 2019 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a serious threat to global public health and social stability. There is an urgent need for understanding the nature and infection mechanism of the virus. Owing to its high infectivity and pathogenicity and lack of effective treatments, live SARS-CoV-2 has to be handled in biosafety level 3 laboratories, which has impeded research into SARS-CoV-2 and the development of vaccines and therapeutics. Pseudotyped viruses that lack certain gene sequences of the virulent virus are safer and can be investigated in biosafety level 2 laboratories, providing a useful virological tool for the study of SARS-CoV-2. In this review, we will discuss the construction of SARS-CoV-2 pseudoviruses based on different packaging systems, current applications, limitations, and further explorations.

Keywords: COVID-19; SARS-CoV-2; packaging system; pseudovirus; spike protein.

Figure 1

The strategies to acquire SARS-CoV-2 pseudoviruses based on different packaging systems. (a) HEK 293T cells were transfected with a plasmid encoding lentiviral backbone and a plasmid expressing SARS-CoV-2 Spike. The transfected cells produced Spike-pseudotyped lentiviral particles and these viral particles can infect cells that express the ACE2 receptor. (b) HEK 293T cells were co-transfected with an Spike encoding-plasmid, an MLV Gag-Pol packaging construct and the MLV transfer vector encoding a luciferase reporter. The transfected cells produced Spike-pseudotyped MLV particles and these viral particles can infect cells that express the ACE2 receptor. (c) HEK 293T cells were transfected with SARS-CoV-2 Spike expression plasmid, after 24 h post-transfection, the cells were inoculated with VSV*∆G (Fluc) encoding firefly luciferase. After an incubation period of 1h at 37 ℃, the inoculum was removed and cells were washed with PBS before medium supplemented with anti VSV-G antibody was added in order to neutralize residual input virus. Spike-pseudotyped particles were harvested 20 h postinoculation and could infect cells that express the ACE2 receptor.