TY - GEN T1 - Virulence Determinants of Avian H5N1 Influenza A Virus in Mammalian and Avian Hosts: Role of the C-Terminal ESEV Motif in the Viral NS1 Protein AU - Zielecki, Florian AU - Semmler, Ilia AU - Kalthoff, Donata AU - Voss, Daniel AU - Mauel, Susanne AU - Gruber, Achim D. AU - Beer, Martin AU - Wolff, Thorsten AB - We assessed the prediction that access of the viral NS1 protein to cellular PDZ domain protein networks enhances the virulence of highly pathogenic avian influenza A viruses. The NS1 proteins of most avian influenza viruses bear the C-terminal ligand sequence Glu-Ser-Glu-Val (ESEV) for PDZ domains present in multiple host proteins, whereas no such motif is found in the NS1 homologues of seasonal human virus strains. Previous analysis showed that a C-terminal ESEV motif increases viral virulence when introduced into the NS1 protein of mouse-adapted H1N1 influenza virus. To examine the role of the PDZ domain ligand motif in avian influenza virus virulence, we generated three recombinants, derived from the prototypic H5N1 influenza A/Vietnam/1203/04 virus, expressing NS1 proteins that either have the C-terminal ESEV motif or the human influenza virus RSKV consensus or bear a natural truncation of this motif, respectively. Cell biological analyses showed strong control of NS1 nuclear migration in infected mammalian and avian cells, with only minor differences between the three variants. The ESEV sequence attenuated viral replication on cultured human, murine, and duck cells but not on chicken fibroblasts. However, all three viruses caused highly lethal infections in mice and chickens, with little difference in viral titers in organs, mean lethal dose, or intravenous pathogenicity index. These findings demonstrate that a PDZ domain ligand sequence in NS1 contributes little to the virulence of H5N1 viruses in these hosts, and they indicate that this motif modulates viral replication in a strain- and host-dependent manner. KW - Cell Line KW - Humans KW - Female KW - Animals KW - Mice KW - Viral Nonstructural Proteins/genetics KW - Influenza A Virus KW - Genetic Variation KW - Species Specificity KW - Recombinant Proteins/metabolism KW - Virulence/genetics KW - Chick Embryo KW - Amino Acid Motifs KW - Chickens KW - Ducks KW - Host-Pathogen Interactions/genetics KW - Host-Pathogen Interactions/immunology KW - Host-Pathogen Interactions/physiology KW - H5N1 Subtype/genetics KW - Influenza A Virus H5N1 Subtype/pathogenicity KW - H5N1 Subtype/physiology KW - Influenza in Birds/etiology KW - Influenza in Birds/virology KW - Interferon-beta/biosynthesis KW - Interferon-beta/genetics KW - Mice Inbred BALB C KW - Orthomyxoviridae Infections/etiology KW - Orthomyxoviridae Infections/pathology KW - Orthomyxoviridae Infections/virology KW - Recombinant Proteins/chemistry KW - Recombinant Proteins/genetics KW - Viral Nonstructural Proteins/chemistry KW - Viral Nonstructural Proteins/physiology KW - Virulence/physiology KW - 610 Medizin PY - 2010 LA - eng PB - Robert Koch-Institut, Infektionskrankheiten / Erreger VL - 84 IS - 20 DO - 10.1128/JVI.00610-10 ER -