pH-dependent entry of severe acute respiratory syndrome coronavirus is mediated by the spike glycoprotein and enhanced by dendritic cell transfer through DC-SIGN.
The severe acute respiratory syndrome coronavirus (SARS-CoV) synthesizes several putative viral envelope proteins, including the spike (S), membrane (M), and small envelope (E) glycoproteins. Although these proteins likely are essential for viral replication, their specific roles in SARS-CoV entry have not been defined. In this report, we show that the SARS-CoV S glycoprotein mediates viral entry through pH-dependent endocytosis. Further, we define its cellular tropism and demonstrate that virus transmission occurs through cell-mediated transfer by dendritic cells. The S glycoprotein was used successfully to pseudotype replication-defective retroviral and lentiviral vectors that readily infected Vero cells as well as primary pulmonary and renal epithelial cells from human, nonhuman primate, and, to a lesser extent, feline species. The tropism of this reporter virus was similar to that of wild-type, replication-competent SARS-CoV, and binding of purified S to susceptible target cells was demonstrated by flow cytometry. Although myeloid dendritic cells were able to interact with S and to bind virus, these cells could not be infected by SARS-CoV. However, these cells were able to transfer the virus to susceptible target cells through a synapse-like structure. Both cell-mediated infection and direct infection were inhibited by anti-S antisera, indicating that strategies directed toward this gene product are likely to confer a therapeutic benefit for antiviral drugs or the development of a SARS vaccine.
Yang
Zhi-Yong
ZY
Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bldg. 40, Room 4502, MSC-3005, 40 Convent Dr., Bethesda, MD 20892-3005, USA.
Huang
Yue
Y
Ganesh
Lakshmanan
L
Leung
Kwanyee
K
Kong
Wing-Pui
WP
Schwartz
Owen
O
Subbarao
Kanta
K
Nabel
Gary J
GJ
D000818:Animals; D015815:Cell Adhesion Molecules / Q000502:physiology*; D002460:Cell Line; D003713:Dendritic Cells / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D037181:Lectins, C-Type / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology*; D045473:Severe acute respiratory syndrome-related coronavirus / Q000502:physiology*; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins / Q000502:physiology*; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin
D015815:Cell Adhesion Molecules; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin