A gammaherpesvirus complement regulatory protein promotes initiation of infection by activation of protein kinase Akt/PKB.
    
    
        
    
    
        
        PLoS ONE 5:e11672 (2010)
    
    
    
      
      
	
	    BACKGROUND: Viruses have evolved to evade the host's complement system. The open reading frames 4 (ORF4) of gammaherpesviruses encode homologs of regulators of complement activation (RCA) proteins, which inhibit complement activation at the level of C3 and C4 deposition. Besides complement regulation, these proteins are involved in heparan sulfate and glycosaminoglycan binding, and in case of MHV-68, also in viral DNA synthesis in macrophages. METHODOLOGY/PRINCIPAL FINDINGS: Here, we made use of MHV-68 to study the role of ORF4 during infection of fibroblasts. While attachment and penetration of virions lacking the RCA protein were not affected, we observed a delayed delivery of the viral genome to the nucleus of infected cells. Analysis of the phosphorylation status of a variety of kinases revealed a significant reduction in phosphorylation of the protein kinase Akt in cells infected with ORF4 mutant virus, when compared to cells infected with wt virus. Consistent with a role of Akt activation in initial stages of infection, inhibition of Akt signaling in wt virus infected cells resulted in a phenotype resembling the phenotype of the ORF4 mutant virus, and activation of Akt by addition of insulin partially reversed the phenotype of the ORF4 mutant virus. Importantly, the homologous ORF4 of KSHV was able to rescue the phenotype of the MHV-68 ORF4 mutant, indicating that ORF4 is functionally conserved and that ORF4 of KSHV might have a similar function in infection initiation. CONCLUSIONS/SIGNIFICANCE: In summary, our studies demonstrate that ORF4 contributes to efficient infection by activation of the protein kinase Akt and thus reveal a novel function of a gammaherpesvirus RCA protein.
	
	
	    
	
       
      
	
	    
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        Publication type
        Article: Journal article
    
 
    
        Document type
        Scientific Article
    
 
    
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        Keywords
        Virus; immune response; protein VCP; SARCOMA-ASSOCIATED HERPESVIRUS; BACTERIAL ARTIFICIAL CHROMOSOME; FOCAL ADHESION KINASE; EPSTEIN-BARR VIRUS; PHOSPHATIDYLINOSITOL 3-KINASE; MONOCLONAL-ANTIBODIES; MICROTUBULE DYNAMICS; SIGNAL-TRANSDUCTION; PSEUDORABIES VIRUS; IMMUNE EVASION
    
 
    
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        Language
        english
    
 
    
        Publication Year
        2010
    
 
    
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        HGF-reported in Year
        2010
    
 
    
    
        ISSN (print) / ISBN
        1932-6203
    
 
    
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	    Volume: 5,  
	    Issue: 7,  
	    Pages: ,  
	    Article Number: e11672 
	    Supplement: ,  
	
    
 
    
        
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            Publisher
            Public Library of Science (PLoS)
        
 
        
            Publishing Place
            Lawrence, Kan.
        
 
	
        
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        Reviewing status
        Peer reviewed
    
 
    
        Institute(s)
        CCG Hematopoetic Cell Transplants (IMI-KHZ)
    
 
    
        POF-Topic(s)
        30504 - Mechanisms of Genetic and Environmental Influences on Health and Disease
    
 
    
        Research field(s)
        Immune Response and Infection
    
 
    
        PSP Element(s)
        G-520300-001
    
 
    
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        Erfassungsdatum
        2010-07-30