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
Creators: name: Zielecki, Florian
name: Semmler, Ilia
name: Kalthoff, Donata
name: Voss, Daniel
name: Mauel, Susanne
name: Gruber, Achim D.
name: Beer, Martin
name: Wolff, Thorsten
Publisher: name: Robert Koch-Institut, Infektionskrankheiten / Erreger
Year: 2010
Subjects: subject: Cell Line
subject: Humans
subject: Female
subject: Animals
subject: Mice
subject: Viral Nonstructural Proteins/genetics
subject: Influenza A Virus
subject: Genetic Variation
subject: Species Specificity
subject: Recombinant Proteins/metabolism
subject: Virulence/genetics
subject: Chick Embryo
subject: Amino Acid Motifs
subject: Chickens
subject: Ducks
subject: Host-Pathogen Interactions/genetics
subject: Host-Pathogen Interactions/immunology
subject: Host-Pathogen Interactions/physiology
subject: H5N1 Subtype/genetics
subject: Influenza A Virus H5N1 Subtype/pathogenicity
subject: H5N1 Subtype/physiology
subject: Influenza in Birds/etiology
subject: Influenza in Birds/virology
subject: Interferon-beta/biosynthesis
subject: Interferon-beta/genetics
subject: Mice Inbred BALB C
subject: Orthomyxoviridae Infections/etiology
subject: Orthomyxoviridae Infections/pathology
subject: Orthomyxoviridae Infections/virology
subject: Recombinant Proteins/chemistry
subject: Recombinant Proteins/genetics
subject: Viral Nonstructural Proteins/chemistry
subject: Viral Nonstructural Proteins/physiology
subject: Virulence/physiology
subject: 610 Medizin

description: 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.