Marburg (MARV) and Ebola (EBOV) viruses are zoonotic pathogens that cause severe
hemorrhagic fever in humans. The natural reservoir of MARV is the Egyptian rousette bat
(Rousettus aegyptiacus); that of EBOV is unknown but believed to be another bat species.
The Egyptian rousette develops subclinical productive infection with MARV but is refractory
to EBOV. Interaction of filoviruses with hosts is greatly affected by the viral interferon
(IFN)-inhibiting domains (IID). Our study was aimed at characterization of innate immune
responses to filoviruses and the role of filovirus IID in bat and human cells. The study
demonstrated that EBOV and MARV replicate to similar levels in all tested cell lines,
indicat... More
Marburg (MARV) and Ebola (EBOV) viruses are zoonotic pathogens that cause severe
hemorrhagic fever in humans. The natural reservoir of MARV is the Egyptian rousette bat
(Rousettus aegyptiacus); that of EBOV is unknown but believed to be another bat species.
The Egyptian rousette develops subclinical productive infection with MARV but is refractory
to EBOV. Interaction of filoviruses with hosts is greatly affected by the viral interferon
(IFN)-inhibiting domains (IID). Our study was aimed at characterization of innate immune
responses to filoviruses and the role of filovirus IID in bat and human cells. The study
demonstrated that EBOV and MARV replicate to similar levels in all tested cell lines,
indicating that permissiveness for EBOV at cell and organism levels do not necessarily
correlate. Filoviruses, particularly MARV, induced a potent innate immune response in
rousette cells, which was generally stronger than in human cells. Both EBOV VP35 and
VP24 IID were found to suppress the innate immune response in rousette cells, but only
VP35 IID appeared to promote virus replication. Along with IFNα and IFNβ, IFNγ was
demonstrated to control filovirus infection in bat cells but not in human cells suggesting host
species specificity of the antiviral effect. The antiviral effects of bat IFNs appeared not to
correlate with induction of IFN-stimulated genes 54 and 56, which was detected in human
cells ectopically expressing bat IFNα and IFNβ. As bat IFNγ induced the type I IFN pathway,
its antiviral effect is likely to be partially induced via ‘cross talk’.