S protein of severe acute respiratory syndrome-associated coronavirus mediates entry into hepatoma cell lines and is targeted by neutralizing antibodies in infected patients.
The severe acute respiratory syndrome-associated coronavirus (SARS-CoV) causes severe pneumonia with a fatal outcome in approximately 10% of patients. SARS-CoV is not closely related to other coronaviruses but shares a similar genome organization. Entry of coronaviruses into target cells is mediated by the viral S protein. We functionally analyzed SARS-CoV S using pseudotyped lentiviral particles (pseudotypes). The SARS-CoV S protein was found to be expressed at the cell surface upon transient transfection. Coexpression of SARS-CoV S with human immunodeficiency virus-based reporter constructs yielded viruses that were infectious for a range of cell lines. Most notably, viral pseudotypes harboring SARS-CoV S infected hepatoma cell lines but not T- and B-cell lines. Infection of the hepatoma cell line Huh-7 was also observed with replication-competent SARS-CoV, indicating that hepatocytes might be targeted by SARS-CoV in vivo. Inhibition of vacuolar acidification impaired infection by SARS-CoV S-bearing pseudotypes, indicating that S-mediated entry requires low pH. Finally, infection by SARS-CoV S pseudotypes but not by vesicular stomatitis virus G pseudotypes was efficiently inhibited by a rabbit serum raised against SARS-CoV particles and by sera from SARS patients, demonstrating that SARS-CoV S is a target for neutralizing antibodies and that such antibodies are generated in SARS-CoV-infected patients. Our results show that viral pseudotyping can be employed for the analysis of SARS-CoV S function. Moreover, we provide evidence that SARS-CoV infection might not be limited to lung tissue and can be inhibited by the humoral immune response in infected patients.
Hofmann
Heike
H
Institute for Clinical and Molecular Virology, University Erlangen-Nürnberg, Nikolaus-Fiebiger-Center, Glückstrasse 6, D-91054 Erlangen, Germany.
Hattermann
Kim
K
Marzi
Andrea
A
Gramberg
Thomas
T
Geier
Martina
M
Krumbiegel
Mandy
M
Kuate
Seraphin
S
Uberla
Klaus
K
Niedrig
Matthias
M
Pöhlmann
Stefan
S
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D006528:Carcinoma, Hepatocellular; D002460:Cell Line; D045744:Cell Line, Tumor; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000821:virology; D016086:Lentivirus / Q000235:genetics; D008099:Liver / Q000166:cytology / Q000821:virology*; D008113:Liver Neoplasms; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D009500:Neutralization Tests; D011817:Rabbits; D045473:Severe acute respiratory syndrome-related coronavirus / Q000472:pathogenicity*; D045169:Severe Acute Respiratory Syndrome / Q000276:immunology / Q000821:virology*; D064370:Spike Glycoprotein, Coronavirus; D014162:Transfection; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014771:Virion
D000914:Antibodies, Viral; D008562:Membrane Glycoproteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus