title: Interferon-gamma and interleukin-4 downregulate expression of the SARS coronavirus receptor ACE2 in Vero E6 cells.
abstract: Interferons (IFNs) inhibit severe acute respiratory syndrome coronavirus (SARS-CoV) replication and might be valuable for SARS treatment. In this study, we demonstrate that treatment of Vero E6 cells with interleukin-4 (IL-4) decreased the susceptibility of these cells to SARS-CoV infection. In contrast to IFNs, IL-4 did not show antiviral activity when administered immediately after SARS-CoV infection, suggesting that IL-4 acts early during the SARS-CoV replication cycle. Indeed, binding of recombinant SARS-CoV spike protein to Vero E6 cells was diminished on cells treated with IL-4, but also on cells exposed to IFN-gamma. Consistent with these observations, IL-4 and IFN-gamma downregulated cell surface expression of angiotensin-converting enzyme 2 (ACE2), the SARS-CoV receptor. Besides diminished ACE2 cell surface expression, ACE2 mRNA levels were also decreased after treatment with these cytokines. These findings suggest that IL-4 and IFN-gamma inhibit SARS-CoV replication partly through downregulation of ACE2.
authors.affiliation: Department of Virology, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands.
authors.forename: Anna
authors.initials: A
authors.lastname: de Lang
authors.forename: Albert D M E
authors.initials: AD
authors.lastname: Osterhaus
authors.forename: Bart L
authors.initials: BL
authors.lastname: Haagmans
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002522:Chlorocebus aethiops; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D007371:Interferon-gamma / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D011991:Receptors, Virus / Q000187:drug effects / Q000378:metabolism*; D045473:Severe acute respiratory syndrome-related coronavirus / Q000502:physiology*; D045169:Severe Acute Respiratory Syndrome / Q000821:virology; D013997:Time Factors; D014709:Vero Cells / Q000187:drug effects / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D011991:Receptors, Virus; D015847:Interleukin-4; D007371:Interferon-gamma