title: Measles Epidemics Among Children in Vietnam: Genomic Characterization of Virus Responsible for Measles Outbreak in Ho Chi Minh City, 2014.
abstract: BACKGROUND
  Measles remains poorly controlled in Southeast Asia, including Vietnam.
  
  
  OBJECTIVE
  The aim of this study was to characterize genes of virus responsible for a measles outbreak among children in Vietnam in 2014.
  
  
  METHODS
  Throat swab samples were collected from 122 pediatric patients with suspected measles. Furthermore, peripheral blood mononuclear cells (PBMCs) from 31 of these cases were also collected. Measles virus (MV) RNA was obtained directly from the clinical specimens, amplified by PCR, and then the N and H genes were sequenced.
  
  
  RESULTS
  MV RNA was detectable in throat swabs from all 122 patients tested. Positive-strand viral RNA, which indicates the intermediate replicative form of MV, was also detected in PBMCs from all 31 cases from whom these cells were collected. One hundred and eighteen strains with the N gene were obtained by RT-PCR and sequenced. Using phylogenetic analysis with measles reference sequences, all of the Vietnamese strains were found to be genotype D8. However, all strains formed a distinct cluster within the genotype D8 group (D8-VNM) suggesting their own lineage. This distinct cluster was supported by a branch with a 99% bootstrap value and 3.3% nucleotide divergence in the N-450 region of the N gene from the D8 reference strain. Notably, all of the D8-VNM variant strains represented unique amino acid sequences consisting of R442, S451 and G452 in the N-450 region of the N gene.
  
  
  CONCLUSIONS
  Measles viruses responsible for outbreaks in Southern Vietnam belonged to a genotype D8 variant group which had unique amino acid sequences in the N gene. Our report provides important genomic information about the virus for measles elimination in Southeast Asia.
authors.affiliation: Center for Molecular Biomedicine, School of Medicine, University of Medicine and Pharmacy in Ho Chi Minh City, Ho Chi Minh City, Vietnam ; Molecular Diagnostics Section, Nam Khoa-Biotek Laboratory, Ho Chi Minh City, Vietnam.
authors.forename: Van H
authors.initials: VH
authors.lastname: Pham
authors.affiliation: Department of Respiratory Diseases, Children Hospital No. 1, Ho Chi Minh City, Vietnam.
authors.forename: Diem P H
authors.initials: DP
authors.lastname: Nguyet
authors.affiliation: Department of Respiratory Diseases, Children Hospital No. 1, Ho Chi Minh City, Vietnam.
authors.forename: Khanh N H
authors.initials: KN
authors.lastname: Mai
authors.affiliation: Department of Infectious Diseases, Children Hospital No. 1, Ho Chi Minh City, Vietnam.
authors.forename: Khanh H
authors.initials: KH
authors.lastname: Truong
authors.affiliation: Molecular Diagnostics Section, Nam Khoa-Biotek Laboratory, Ho Chi Minh City, Vietnam.
authors.forename: Loc V
authors.initials: LV
authors.lastname: Huynh
authors.affiliation: Molecular Diagnostics Section, Nam Khoa-Biotek Laboratory, Ho Chi Minh City, Vietnam.
authors.forename: Trang H T
authors.initials: TH
authors.lastname: Pham
authors.affiliation: Center for Molecular Biomedicine, School of Medicine, University of Medicine and Pharmacy in Ho Chi Minh City, Ho Chi Minh City, Vietnam ; Molecular Diagnostics Section, Nam Khoa-Biotek Laboratory, Ho Chi Minh City, Vietnam ; Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Abe
keywords: Measles; Measles virus; Southeast Asia; Vietnam; Virus genotype