title: Hepatitis C virus diversification in Argentina: comparative analysis between the large city of Buenos Aires and the small rural town of O'Brien.
abstract: BACKGROUND
  The estimated prevalence of HCV infection in Argentina is around 2%. However, higher rates of infection have been described in population studies of small urban and rural communities. The aim of this work was to compare the origin and diversification of HCV-1b in samples from two different epidemiological scenarios: Buenos Aires, a large cosmopolitan city, and O'Brien, a small rural town with a high prevalence of HCV infection.
  
  
  METHODS
  The E1/E2 and NS5B regions of the viral genome from 83 patients infected with HCV-1b were sequenced. Phylogenetic analysis and Bayesian Coalescent methods were used to study the origin and diversification of HCV-1b in both patient populations.
  
  
  RESULTS
  Samples from Buenos Aires showed a polyphyletic behavior with a tMRCA around 1887-1900 and a time of spread of infection approximately 60 years ago. In contrast, samples from ÓBrien showed a monophyletic behavior with a tMRCA around 1950-1960 and a time of spread of infection more recent than in Buenos Aires, around 20-30 years ago.
  
  
  CONCLUSIONS
  Phylogenetic and coalescence analysis revealed a different behavior in the epidemiological histories of Buenos Aires and ÓBrien. HCV infection in Buenos Aires shows a polyphyletic behavior and an exponential growth in two phases, whereas that in O'Brien shows a monophyletic cluster and an exponential growth in one single step with a more recent tMRCA. The polyphyletic origin and the probability of encountering susceptible individuals in a large cosmopolitan city like Buenos Aires are in agreement with a longer period of expansion. In contrast, in less populated areas such as O'Brien, the chances of HCV transmission are strongly restricted. Furthermore, the monophyletic character and the most recent time of emergence suggest that different HCV-1b ancestors (variants) that were in expansion in Buenos Aires had the opportunity to colonize and expand in O'Brien.
authors.affiliation: Cátedra de Virología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Marcelo D
authors.initials: MD
authors.lastname: Golemba
authors.affiliation: Cátedra de Virología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Andrés C A
authors.initials: AC
authors.lastname: Culasso
authors.affiliation: Unidad de Trasplante Hepático, Hospital Británico de Buenos Aires, Argentina y Unidad de Trasplante Hepático, Hospital El Cruce, Buenos Aires, Argentina.
authors.forename: Federico G
authors.initials: FG
authors.lastname: Villamil
authors.affiliation: Sección Virología, Academia Nacional de Medicina, Buenos Aires, Argentina.
authors.forename: Patricia
authors.initials: P
authors.lastname: Bare
authors.affiliation: Hepatology Unit, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Adrián
authors.initials: A
authors.lastname: Gadano
authors.affiliation: Centro de Educación Médica e Investigaciones Clínicas Norberto Quirno, CEMIC, Buenos Aires, Argentina.
authors.forename: Ezequiel
authors.initials: E
authors.lastname: Ridruejo
authors.affiliation: Centro de Educación Médica e Investigaciones Clínicas Norberto Quirno, CEMIC, Buenos Aires, Argentina.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Martinez
authors.affiliation: Cátedra de Virología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Federico A
authors.initials: FA
authors.lastname: Di Lello
authors.affiliation: Cátedra de Virología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Rodolfo H
authors.initials: RH
authors.lastname: Campos
mesh_terms: D000368:Aged; D001118:Argentina / Q000453:epidemiology; D001499:Bayes Theorem; D044822:Biodiversity; D002947:Cities / Q000453:epidemiology*; D005260:Female; D005838:Genotype; D016174:Hepacivirus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D006526:Hepatitis C / Q000453:epidemiology / Q000821:virology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D015995:Prevalence; D012424:Rural Population / Q000706:statistics & numerical data*