RESUMO
Malaysia is a medium endemic country for hepatitis B virus (HBV) infection but little is known about HBV strains circulating in Malaysian blood donors. Viral load, HBsAg concentrations and nested PCR products from 84 HBV surface antigen (HBsAg) positive samples were analysed in detail. Median viral load was 3050 IU/mL and median HBsAg 1150 IU/mL. Fifty-six full genome, 20 pre-S/S, 1 S gene and six basic core promoter/precore-only sequences were obtained. Genotypes B and C were present at a ratio of 2:1, and two genotype D samples were obtained, both from donors of Indian background. Phylogenetically, genotype B was more diverse with subgenotypes B2-5, B7 and B8 present, while most genotype C strains were from subgenotype C1. Genotypes B and C were equally frequent in ethnic Malays, but 80% of strains from Chinese were genotype B. HBsAg concentrations were higher in genotype C than in genotype B, in Chinese than Malays and in donors under the age of 30. HBV vaccine escape substitutions (P120S/T, I126N and G145G) were present in six strains. In the large surface protein, immuno-inactive regions were more mutated than CD8 epitopes and the major hydrophilic region. Strains of genotype B or from ethnic Malays had higher genetic diversity than strains of genotype C or from Chinese donors. Hence HBV strains circulating in Malaysia are phylogenetically diverse reflecting the ethnic mix of its population. Ethnic Malays carry lower HBsAg levels and higher genetic diversity of the surface antigen, possibly resulting in more effective immune control of the infection.
Assuntos
Variação Genética , Vírus da Hepatite B/classificação , Vírus da Hepatite B/isolamento & purificação , Hepatite B/virologia , Interações Hospedeiro-Patógeno , Adolescente , Adulto , Doadores de Sangue , DNA Viral/sangue , DNA Viral/genética , Epitopos/genética , Epitopos/imunologia , Feminino , Genótipo , Hepatite B/imunologia , Antígenos de Superfície da Hepatite B/sangue , Vírus da Hepatite B/genética , Vírus da Hepatite B/imunologia , Humanos , Evasão da Resposta Imune , Malásia , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Filogenia , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Carga Viral , Adulto JovemRESUMO
A retrospective study was undertaken to identify recipients of blood from donors subsequently shown to be positive for hepatitis C virus using second-generation tests and polymerase chain reaction. The main aims were to determine the numbers of such recipients who were still alive and traceable, and to determine the risk of infection in this group. The feasibility and workload of this procedure, which is currently not practised in the U.K. or U.S.A., was also assessed. In the first six months of routine testing 42,697 donors were tested. Of 20 confirmed to be HCV-positive, 15 were regular donors. Eighty-three components were prepared from 63 anti-HCV positive previous donations from these donors. In all, nine recipients were found to be alive. All were positive for anti-HCV. We conclude that although this retrospective procedure is time-consuming and difficult, substantial numbers of infected recipients can be identified. The availability of treatment for chronic hepatitis C for such patients should encourage transfusion services to reassess current policies on the hepatitis C retrospective.