Pseudotyped vesicular stomatitis virus for analysis of virus entry mediated by SARS coronavirus spike proteins

Severe acute respiratory syndrome (SARS) coronavirus (CoV) contains a spike (S) protein that binds to a receptor molecule (angiotensin-converting enzyme 2; ACE2), induces membrane fusion, and serves as a neutralizing epitope. To study the functions of the S protein, we describe here the generation of SARS-CoV S protein-bearing vesicular stomatitis virus (VSV) pseudotype using a VSVdeltaG*/GFP system in which the G gene is replaced by the green fluorescent protein (GFP) gene (VSV-SARS-CoV-St19/GFP). Partial deletion of the cytoplasmic domain of SARS-CoV S protein (SARS-CoV-St19) allowed efficient incorporation into the VSV particle that enabled the generation of a high titer of pseudotype virus. Neutralization assay with anti-SARS-CoV antibody revealed that VSV-SARS-St19/GFP pseudotype infection is mediated by SARS-CoV S protein. The VSVdeltaaG*/SEAP system, which secretes alkaline phosphatase instead of GFP, was also generated as a VSV pseudotype having SARS-CoV S protein (VSV-SARS-CoV-St19/SEAP). This system enabled high-throughput analysis of SARS-CoV S protein-mediated cell entry by measuring alkaline phosphatase activity. Thus, VSV pseudotyped with SARS-CoV S protein is useful for developing a rapid detection system for neutralizing antibody specific for SARS-CoV infection as well as studying the S-mediated cell entry of SARS-CoV.