title: Detection and Characterization of Clade 1 Reassortant H5N1 Viruses Isolated from Human Cases in Vietnam during 2013.
abstract: Highly pathogenic avian influenza (HPAI) H5N1 is endemic in Vietnamese poultry and has caused sporadic human infection in Vietnam since 2003. Human infections with HPAI H5N1 are of concern due to a high mortality rate and the potential for the emergence of pandemic viruses with sustained human-to-human transmission. Viruses isolated from humans in southern Vietnam have been classified as clade 1 with a single genome constellation (VN3) since their earliest detection in 2003. This is consistent with detection of this clade/genotype in poultry viruses endemic to the Mekong River Delta and surrounding regions. Comparison of H5N1 viruses detected in humans from southern Vietnamese provinces during 2012 and 2013 revealed the emergence of a 2013 reassortant virus with clade 1.1.2 hemagglutinin (HA) and neuraminidase (NA) surface protein genes but internal genes derived from clade 2.3.2.1a viruses (A/Hubei/1/2010-like; VN12). Closer analysis revealed mutations in multiple genes of this novel genotype (referred to as VN49) previously associated with increased virulence in animal models and other markers of adaptation to mammalian hosts. Despite the changes identified between the 2012 and 2013 genotypes analyzed, their virulence in a ferret model was similar. Antigenically, the 2013 viruses were less cross-reactive with ferret antiserum produced to the clade 1 progenitor virus, A/Vietnam/1203/2004, but reacted with antiserum produced against a new clade 1.1.2 WHO candidate vaccine virus (A/Cambodia/W0526301/2012) with comparable hemagglutination inhibition titers as the homologous antigen. Together, these results indicate changes to both surface and internal protein genes of H5N1 viruses circulating in southern Vietnam compared to 2012 and earlier viruses.
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Sharmi W
authors.initials: SW
authors.lastname: Thor
authors.affiliation: Institute Pasteur-Ho Chi Minh City, National Influenza Center-2, Ho Chi Minh City, Vietnam.
authors.forename: Hieu
authors.initials: H
authors.lastname: Nguyen
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Amanda
authors.initials: A
authors.lastname: Balish
authors.affiliation: Institute Pasteur-Ho Chi Minh City, National Influenza Center-2, Ho Chi Minh City, Vietnam.
authors.forename: Anh Nguyen
authors.initials: AN
authors.lastname: Hoang
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Kortney M
authors.initials: KM
authors.lastname: Gustin
authors.affiliation: Institute Pasteur-Ho Chi Minh City, National Influenza Center-2, Ho Chi Minh City, Vietnam.
authors.forename: Pham Thi
authors.initials: PT
authors.lastname: Nhung
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Joyce
authors.initials: J
authors.lastname: Jones
authors.affiliation: Institute Pasteur-Ho Chi Minh City, National Influenza Center-2, Ho Chi Minh City, Vietnam.
authors.forename: Ngoc Nguyen
authors.initials: NN
authors.lastname: Thu
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: William
authors.initials: W
authors.lastname: Davis
authors.affiliation: Institute Pasteur-Ho Chi Minh City, National Influenza Center-2, Ho Chi Minh City, Vietnam.
authors.forename: Thao Nguyen Thi
authors.initials: TN
authors.lastname: Ngoc
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Yunho
authors.initials: Y
authors.lastname: Jang
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Katrina
authors.initials: K
authors.lastname: Sleeman
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Julie
authors.initials: J
authors.lastname: Villanueva
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America; Influenza Program, Centers for Disease Control and Prevention- Vietnam, Hanoi, Vietnam.
authors.forename: James
authors.initials: J
authors.lastname: Kile
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Larisa V
authors.initials: LV
authors.lastname: Gubareva
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Stephen
authors.initials: S
authors.lastname: Lindstrom
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Terrence M
authors.initials: TM
authors.lastname: Tumpey
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: C Todd
authors.initials: CT
authors.lastname: Davis
authors.affiliation: Institute Pasteur-Ho Chi Minh City, National Influenza Center-2, Ho Chi Minh City, Vietnam.
authors.forename: Nguyen Thanh
authors.initials: NT
authors.lastname: Long
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016679:Genome, Viral / Q000235:genetics; D005838:Genotype; D006389:Hemagglutinins, Viral / Q000145:classification / Q000235:genetics; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000145:classification / Q000235:genetics / Q000502:physiology*; D005585:Influenza in Birds / Q000453:epidemiology / Q000821:virology*; D007251:Influenza, Human / Q000453:epidemiology / Q000821:virology*; D009439:Neuraminidase / Q000145:classification / Q000235:genetics; D058873:Pandemics; D010802:Phylogeny; D011200:Poultry / Q000821:virology; D011995:Recombination, Genetic; D014744:Vietnam / Q000453:epidemiology; D014764:Viral Proteins / Q000235:genetics
chemical_list: D006389:Hemagglutinins, Viral; D014764:Viral Proteins; D009439:Neuraminidase