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.
Clemente
Cintia Mendes
CM
Departmento de Gastroenterologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo 01246-902, Brazil. cintiamclemente@uol.com.br
Carrilho
Flair José
FJ
Pinho
João Renato Rebello
JR
Ono-Nita
Suzane Kioko
SK
Da Silva
Luiz Caetano
LC
Moreira
Regina Célia
RC
Lemos
Marcílio Figueiredo
MF
de Carvalho Mello
Isabel Maria Vicente Guedes
IM
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