title: H5N1 influenza virus evolution: a comparison of different epidemics in birds and humans (1997-2004).
abstract: The selection pressure acting along the entire genome sequence of H5N1 avian influenza viruses isolated from several bird species and humans infected in the 1997 and 2004 outbreaks, and on the HA1 genes from H5N1 viruses isolated during the entire study period, in eastern Asia was evaluated. According to maximum-likelihood analysis, viral genes appeared to be, in both epidemics, under strong purifying selection, with only the PB2, HA and NS1 genes under positive selection. Specific codons under positive selection were detected by using codon-based substitution models. Positive-selection analysis performed on single-codon sites might be helpful in clarifying the driving force of avian and human influenza virus evolution and in selecting specific targets for vaccines and antiviral drugs.
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Campitelli
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Ciccozzi
authors.affiliation: Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Salemi
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Taglia
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Boros
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Isabella
authors.initials: I
authors.lastname: Donatelli
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Rezza
mesh_terms: D000818:Animals; D001208:Asia / Q000453:epidemiology; D004196:Disease Outbreaks; D019143:Evolution, Molecular; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000145:classification / Q000235:genetics*; D005585:Influenza in Birds / Q000453:epidemiology* / Q000821:virology; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D011200:Poultry / Q000821:virology; D011201:Poultry Diseases / Q000453:epidemiology* / Q000821:virology; D012641:Selection, Genetic; D017361:Viral Nonstructural Proteins / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; C085820:INS1 protein, influenza virus; C502893:PB2 protein, influenza virus; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins