A phylogenetic study of hepatitis B virus in chronically infected Brazilian patients of Western and Asian descent.
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 predominate. Several studies showed that immigrants retain the HBV infection pattern of their ancestral country.


OBJECTIVE
To identify HBV genotypes infecting chronic carriers in Brazilian families of Western and Asian descent by Hepatitis B surface antigen gene sequencing and analyze 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. Analysis 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.
Departmento de Gastroenterologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo 01246-902, Brazil. cintiamclemente@uol.com.br
Cintia Mendes
CM
Clemente
Flair José
FJ
Carrilho
João Renato Rebello
JR
Pinho
Suzane Kioko
SK
Ono-Nita
Luiz Caetano
LC
Da Silva
Regina Célia
RC
Moreira
Marcílio Figueiredo
MF
Lemos
Isabel Maria Vicente Guedes
IM
de Carvalho Mello
D000328:Adult; D001208:Asia / Q000208:ethnology; D001938:Brazil / Q000453:epidemiology; D005060:Europe / Q000208:ethnology; D005260:Female; D005838:Genotype; D006515:Hepatitis B virus / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000235:genetics / Q000821:virology*; D006801:Humans; D008297:Male; D010802:Phylogeny; D016036:Seroepidemiologic Studies; D055815:Young Adult