ORIGINAL ARTICLE—LIVER, PANCREAS, AND BILIARY TRACT A phylogenetic study of hepatitis B virus in chronically infected Brazilian patients of Western and Asian descent Cintia Mendes Clemente Æ Flair Jose ´ Carrilho Æ Joa ˜o Renato Rebello Pinho Æ Suzane Kioko Ono-Nita Æ Luiz Caetano Da Silva Æ Regina Ce ´lia Moreira Æ Marcı ´lio Figueiredo Lemos Æ Isabel Maria Vicente Guedes de Carvalho Mello Received: 22 May 2008 / Accepted: 2 December 2008 / Published online: 16 April 2009 Ó Springer 2009 Abstract Background Hepatitis B virus (HBV) causes one of the most important chronic viral infections worldwide. HBV is classified into eight genotypes whose epidemiology varies geographically. In Brazil, genotypes A, D, and F are more frequent, while in East Asia, genotypes B and C predom- inate. Several studies showed that immigrants retain the HBV infection pattern of their ancestral country. Purpose To identify HBV genotypes infecting chronic carriers in Brazilian families of Western and Asian descent by Hepatitis B surface antigen gene sequencing and ana- lyze the route of viral transmission by phylogenetic analysis of viral sequences. Methods Eighty-seven people chronically infected with HBV were separated into two groups: Western descent (27) and Asian descent (60). Surface and pre-core/core genes were amplified from serum HBV-DNA and sequences were subjected to phylogenetic analysis. Results HBV genotype A was found in 74% of Western subjects, while genotype C was found in 94% of Asian patients. Thirty-eight percent of Western families were infected with HBV with similar pre-core/core sequences, while only 25% of Asian families showed similarity in these sequences. Conclusions Phylogenetical analysis of pre-core/core HBV gene suggested intra-familial transmission of HBV in 38% of Western families and 25% of Asian families. Anal- ysis of HBsAg gene sequences helped to define the HBV genotype but did not allow inferring route of transmission as its sequences showed a smaller phylogenetic signal than pre- core/core sequences. Chronic HBV carriers of Asian descent born in or living in Brazil were infected with the same HBV genotype predominant in their ancestral country. C. M. Clemente (&) Á F. J. Carrilho Á J. R. R. Pinho Á S. K. Ono-Nita Á L. C. D. Silva Á I. M. V. G. de Carvalho Mello Departmento de Gastroenterologia, Faculdade de Medicina, Universidade de Sa ˜o Paulo, Avenida Doutor Arnaldo 455, Sa ˜o Paulo 01246-902, Brazil e-mail: cintiamclemente@uol.com.br F. J. Carrilho e-mail: fjcarril@usp.br J. R. R. Pinho e-mail: jrrpinho@usp.br S. K. Ono-Nita e-mail: skon@usp.br L. C. D. Silva e-mail: lucadasi@bol.com.br I. M. V. G. de Carvalho Mello e-mail: imvgcmello@butantan.gov.br J. R. R. Pinho Laborato ´rio de Hepatologia e Gastroenterologia Tropical, Instituto de Medicina Tropical da Universidade de Sa ˜o Paulo, Avenida Doutor Ene ´as de Carvalho Aguiar 500, Sa ˜o Paulo 05403-000, Brazil R. C. Moreira Á M. F. Lemos Servic ¸o de Virologia, Instituto Adolfo Lutz, Avenida Doutor Arnaldo 355, Sa ˜o Paulo 01246-902, Brazil R. C. Moreira e-mail: rmoreira@ial.sp.gov.br M. F. Lemos e-mail: mflemos@ial.sp.gov.br I. M. V. G. de Carvalho Mello Laborato ´rio de Imunologia Viral, Instituto Butantan, Avenida Doutor Vital Brasil, 1500, Sa ˜o Paulo 05503-900, Brazil 123 J Gastroenterol (2009) 44:568–576 DOI 10.1007/s00535-009-0044-8