Nasal commensal Staphylococcus epidermidis counteracts influenza virus.
Several microbes, including Staphylococcus epidermidis (S. epidermidis), a Gram-positive bacterium, live inside the human nasal cavity as commensals. The role of these nasal commensals in host innate immunity is largely unknown, although bacterial interference in the nasal microbiome may promote ecological competition between commensal bacteria and pathogenic species. We demonstrate here that S. epidermidis culture supernatants significantly suppressed the infectivity of various influenza viruses. Using high-performance liquid chromatography together with mass spectrometry, we identified a giant extracellular matrix-binding protein (Embp) as the major component involved in the anti-influenza effect of S. epidermidis. This anti-influenza activity was abrogated when Embp was mutated, confirming that Embp is essential for S. epidermidis activity against viral infection. We also showed that both S. epidermidis bacterial particles and Embp can directly bind to influenza virus. Furthermore, the injection of a recombinant Embp fragment containing a fibronectin-binding domain into embryonated eggs increased the survival rate of virus-infected chicken embryos. For an in vivo challenge study, prior Embp intranasal inoculation in chickens suppressed the viral titres and induced the expression of antiviral cytokines in the nasal tissues. These results suggest that S. epidermidis in the nasal cavity may serve as a defence mechanism against influenza virus infection.
Department of Veterinary Medicine, National Taiwan University, Taipei, Taiwan.
Hui-Wen
HW
Chen
Department of Dermatology, University of California, San Diego, CA, USA.
Pei-Feng
PF
Liu
Division of Infectious Diseases, Department of Medicine, University of California, San Diego, CA, USA.|Moores Cancer Center, University of California, San Diego, CA, USA.
Yu-Tsueng
YT
Liu
Department of Dermatology, University of California, San Diego, CA, USA.
Sherwin
S
Kuo
Division of Infectious Diseases, Department of Medicine, University of California, San Diego, CA, USA.
Xing-Quan
XQ
Zhang
Division of Infectious Diseases, Department of Medicine, University of California, San Diego, CA, USA.
Robert T
RT
Schooley
Institut für Medizinische Mikrobiologie, Virologie und Hygiene, Universitätsklinikum, Hamburg, Germany.
Holger
H
Rohde
Department of Dermatology, University of California, San Diego, CA, USA.
Richard L
RL
Gallo
Department of Dermatology, University of California, San Diego, CA, USA.|Moores Cancer Center, University of California, San Diego, CA, USA.
Chun-Ming
CM
Huang
D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002642:Chick Embryo; D053118:Influenza A Virus, H1N1 Subtype / Q000378:metabolism*; D064307:Microbiota; D009296:Nasal Cavity / Q000382:microbiology* / Q000821:virology*; D013211:Staphylococcus aureus / Q000378:metabolism*
D001426:Bacterial Proteins; D002352:Carrier Proteins; C469919:Embp32 protein, Staphylococcus epidermidis