title: Origin and evolutionary dynamics of Hepatitis B virus (HBV) genotype E in Madagascar.
abstract: Africa is one of the endemic regions of HBV infection. In particular, genotype E is highly endemic in most of sub-Saharan Africa such as West African countries where it represents more than 90% of total infections. Madagascar, which is classified as a high endemic area for HBV and where the most prevalent genotype is E, might play a relevant role in the dispersion of this genotype due to its crucial position in the Indian Ocean. The aim of this study was to investigate the origin, population dynamics, and circulation of HBV-E genotype in Madagascar through high-resolution phylogenetic and phylodynamic approaches. The phylogenetic tree indicated that Malagasy isolates were intermixed and closely related with sequences mostly from West African countries. The Bayesian tree highlighted three statistically supported clusters of Malagasy strains which dated back to the years 1981 (95% HPD: 1971-1992), 1986 (95% HPD: 1974-1996), and 1989 (95% HPD: 1974-2001). Population dynamics analysis showed an exponential increase in the number of HBV-E infections approximately from the year 1975 until 2000s. The migration analysis was also performed and a dynamic pattern of gene flow was identified. In conclusion, this study confirms previous observation of HBV-E circulation in Africa and expands these findings at Madagascar demonstrating its recent introduction, and highlighting the role of the African countries in the spread of HBV-E genotype. Further studies on molecular epidemiology of HBV genotype E are needed to clarify the evolutionary history of this genotype.
authors.affiliation: a Epidemiology Unit, Department of Infectious, Parasitic and Immune-Mediated Diseases , Istituto Superiore di Sanità , Rome , Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Lo Presti
authors.affiliation: b Virology Unit , Institut Pasteur of Madagascar , Antananarivo , Madagascar.
authors.forename: Soa Fy
authors.initials: SF
authors.lastname: Andriamandimby
authors.affiliation: c Department of Biomedical and Clinical Sciences "Luigi Sacco", Infectious Diseases and Immunopathology Section, 'L. Sacco' Hospital , University of Milan , Milan , Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Lai
authors.affiliation: d Clinical Pathology and Microbiology Laboratory , University Hospital Campus Bio-Medico of Rome , Rome , Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Angeletti
authors.affiliation: a Epidemiology Unit, Department of Infectious, Parasitic and Immune-Mediated Diseases , Istituto Superiore di Sanità , Rome , Italy.|e Public Health and Infectious Diseases , Sapienza University , Rome , Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Cella
authors.affiliation: f University Hospital Campus Bio-Medico , Rome , Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mottini
authors.affiliation: g Digestive Disease Unit of Campus Bio Medico University of Rome , Rome , Italy.
authors.forename: Michele Pier Luca
authors.initials: MP
authors.lastname: Guarino
authors.affiliation: c Department of Biomedical and Clinical Sciences "Luigi Sacco", Infectious Diseases and Immunopathology Section, 'L. Sacco' Hospital , University of Milan , Milan , Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Balotta
authors.affiliation: c Department of Biomedical and Clinical Sciences "Luigi Sacco", Infectious Diseases and Immunopathology Section, 'L. Sacco' Hospital , University of Milan , Milan , Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Galli
authors.affiliation: b Virology Unit , Institut Pasteur of Madagascar , Antananarivo , Madagascar.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Heraud
authors.affiliation: c Department of Biomedical and Clinical Sciences "Luigi Sacco", Infectious Diseases and Immunopathology Section, 'L. Sacco' Hospital , University of Milan , Milan , Italy.
authors.forename: Gianguglielmo
authors.initials: G
authors.lastname: Zehender
authors.affiliation: a Epidemiology Unit, Department of Infectious, Parasitic and Immune-Mediated Diseases , Istituto Superiore di Sanità , Rome , Italy.|f University Hospital Campus Bio-Medico , Rome , Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Ciccozzi
mesh_terms: D001499:Bayes Theorem; D016000:Cluster Analysis; D030541:Databases, Genetic; D019143:Evolution, Molecular; D051456:Gene Flow; D005838:Genotype; D006509:Hepatitis B / Q000453:epidemiology / Q000821:virology*; D006515:Hepatitis B virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008270:Madagascar / Q000453:epidemiology; D010802:Phylogeny; D011157:Population Dynamics
keywords: Hepatitis B virus; Madagascar; migration analysis; phylodynamics; phylogeny