Application of pseudovirus system in the development of vaccine, antiviral-drugs, and neutralizing antibodies

Abstract

Pseudoviruses are viral particles coated with a heterologous envelope protein, which mediates the entry of pseudoviruses as efficiently as that of the live viruses possessing high pathogenicity and infectivity. Due to the deletion of the envelope protein gene and the absence of pathogenic genes, pseudoviruses have no autonomous replication ability and can infect host cells for only a single cycle. In addition, pseudoviruses have the desired characteristics of high safety, strong operability, and can be easily used to perform rapid throughput detection. Therefore, pseudoviruses are widely employed in the mechanistic investigation of viral infection, the screening and evaluation of monoclonal antibodies and antiviral drugs, and the detection of neutralizing antibody titers in serum after vaccination. In this review, we will discuss the construction of pseudoviruses based on different packaging systems, their current applications especially in the research of SARS-CoV-2, limitations, and further directions.

Keywords: Envelope protein; HIV; MLV; Pseudoviruses; SARS-CoV-2; VSV.

Fig. 1

The schematic diagram of acquiring different pseudotyped-viruses based on different packaging systems. (A) HEK 293 T cells were transfected with a plasmid encoding lentiviral backbone and a plasmid expressing envelope protein. The transfected cells produced recombined pseudoviruses and these viral particles could be secreted to extracellular environment before harvesting. (B) HEK 293 T cells were firstly transfected with an envelope protein expression plasmid, twenty-four hours post-transfection, the cells were infected with VSV* ∆G encoding firefly luciferase or GFP. Pseudotyped particles were harvested 20 h post-inoculation. (C) HEK 293 T cells were co-transfected with an envelope protein encoding-plasmid, an MLV Gag-Pol packaging plasmid and the MLV transfer vector encoding a luciferase reporter. The transfected cells produced pseudotyped MLV particles like the HIV systems. Red bar in plasmid represents packaging elements such as gag and pol; green bar in plasmid represents reporter genes, such as GFP and Luciferase; orange bar in plasmid represents envelope protein gene; purple bar in plasmid represents packaging signals, 3’LTR and 5’LTR.

Fig. 2

An overview of mutations in the spike protein of 9 important SARS-CoV-2 variants. (Data from GISAID).