title: Introduction and evolution of dengue virus type 2 in Pakistan: a phylogeographic analysis.
abstract: BACKGROUND
  Pattern of Dengue periodic epidemics through the years along with sporadic cases of Dengue hemorrhagic fever followed by a severe 2011 epidemic of Dengue fever in Pakistan make Pakistan a Dengue endemic country. To study the entry and evolution of dengue virus serotype 2 (DENV-2) in Pakistan, we sequenced three full length genomes and 24 complete envelope sequences of DENV-2 from the years 2010, 2011 and 2013 collected from Punjab province of Pakistan.
  
  
  METHODS
  Phylogenetic and Bayesian phylogeographic analyses was applied to three full genome sequences as well as 24 envelope sequences to study the spatiotemporal dynamics of DENV-2 in Pakistan.
  
  
  RESULTS
  Most of the DENV-2 viruses from the years 2008 to 2013 formed a monophyletic Pakistani clade in IVb sublineage of cosmopolitan genotype except one 2008 DENV-2 strain. Phylogeographic analysis revealed that this 2008 DENV-2 strain was rooted to India 25.4 years ago with a location probability of 0.88. However Pakistani clade rooted back to Sri Lanka 12.6 years ago with a location probability of 0.57.
  
  
  CONCLUSIONS
  DENV-2 genotype IV was introduced in Pakistan in two time events. First event was introduction from India to Pakistan in the late 1980s (around 1986), and second event was introduction from Sri Lanka to Pakistan around 2000. The later introduction event was responsible for major outbreaks in the Punjab region of Pakistan, including major 2011 outbreak. After the second Introduction event, DENV-2 circulated locally in the region forming a distinct Sublineage within the IVb cosmopolitan genotype of DENV-2.
authors.affiliation: Division of Molecular Virology, Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan.
authors.forename: Madiha
authors.initials: M
authors.lastname: Akram
authors.affiliation: Division of Molecular Virology, Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan.
authors.forename: Zareen
authors.initials: Z
authors.lastname: Fatima
authors.affiliation: Centre for disease control and prevention, Atlanta, USA.
authors.forename: Mike A
authors.initials: MA
authors.lastname: Purdy
authors.affiliation: Centre for disease control and prevention, Atlanta, USA.
authors.forename: Amanda
authors.initials: A
authors.lastname: Sue
authors.affiliation: Division of Molecular Virology, Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan.
authors.forename: Sana
authors.initials: S
authors.lastname: Saleem
authors.affiliation: Division of Molecular Virology, Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan.
authors.forename: Irum
authors.initials: I
authors.lastname: Amin
authors.affiliation: Division of Molecular Virology, Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Shahid
authors.affiliation: Center for Applied Molecular Biology (CAMB), University of the Punjab, 87-West Canal Bank Road Thokar Niaz Baig Lahore-53700, Lahore, Pakistan. directorcamb@yahoo.com.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Idrees
authors.affiliation: Division of Molecular Virology, Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan.
authors.forename: Rabia
authors.initials: R
authors.lastname: Nawaz
mesh_terms: D016000:Cluster Analysis; D003715:Dengue / Q000453:epidemiology / Q000821:virology*; D003716:Dengue Virus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D004196:Disease Outbreaks; D019143:Evolution, Molecular; D016679:Genome, Viral; D006801:Humans; D007194:India; D008969:Molecular Sequence Data; D010154:Pakistan; D058974:Phylogeography; D012367:RNA, Viral / Q000235:genetics; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013188:Sri Lanka / Q000453:epidemiology
chemical_list: D012367:RNA, Viral