Hepatitis B and Delta: clinical aspects of patients in the Brazilian Western Amazonia / Hepatitis B y Delta: aspectos clínicos de pacientes en el Amazonas brasileño Occidental / Hepatite B e Delta: aspectos clínicos de pacientes na Amazônia Ocidental brasileira

ABSTRACT Objective: to analyze clinical, serological, biochemical and hematological aspects in patients infected with the hepatitis B (HBV) and Delta (HDV) viruses. Method: cross-sectional, descriptive and retrospective study, performed with patients chronically infected with HBV and superinfected with HDV. Results: among the 112 patients selected, 74% were monoinfected with HBV (Group HBV) and 26% were superinfected with HDV (Group HBV+HDV). There was no difference in gender distribution. The average age was 36 years with standard deviation of ±12 years. The symptoms and signs presented a higher proportion in Group HBV+HDV (p=0.001). In both groups, most patients had non-reactive AgHBe. The records of biochemical and hematologic changes showed highest proportion in Group VHB+VHD Group (p<0.05). Conclusion: the study found that patients were in clinical stages of the disease different from those in the initial examination for monitoring their chronic condition. The clinical profile suggests greater severity of liver disease among the patients superinfected with HDV.

RESUMEN Objetivo: Analizar los aspectos clínicos, serológicos, bioquímicos y hematológicos de pacientes infectados por el virus de las hepatitis B (VHB) y Delta (VHD). Método: Se trata de un estudio transversal, descriptivo, retrospectivo, realizado entre pacientes crónicos infectados de VHB y sobre infectados de VHD. Resultados: Entre los 112 pacientes seleccionados, el 74% estaba mono infectado por VHB (Grupo VHB) y el 26%, sobre infectado por VHD (Grupo VHB+VHD). No se encontró diferencia en la distribución por género. La edad promedio era 36 años, con desviación típica de ±12 años. Los síntomas y signos sobresalían en mayor proporción en el grupo VHB+VHD (p=0,001). Para ambos grupos, la mayoría de los pacientes estaba con AgHBe no reactivo. El registro de alteraciones bioquímicas y hematológicas atribuyó proporción más grande al grupo VHB+VHD (p<0,05). Conclusión: El estudio demostró que los pacientes, en la consulta inicial para el seguimiento de la condición crónica, estaban en diferentes estadios clínicos de la enfermedad. El perfil clínico sugiere que la gravedad de la enfermedad hepática es mayor entre pacientes sobre infectados de VHD.

RESUMO Objetivo: Analisar aspectos clínicos, sorológicos, bioquímicos e hematológicos entre pacientes infectados por vírus das hepatites B (VHB) e Delta (VHD). Método: Estudo transversal, descritivo, retrospectivo, realizado com pacientes cronicamente infectados por VHB e superinfectados por VHD. Resultados: Entre os 112 pacientes selecionados, 74% estavam monoinfectados por VHB (Grupo VHB) e 26% superinfectados por VHD (Grupo VHB+VHD). Não houve diferença na distribuição por gênero. A idade média foi de 36 anos, com desvio padrão de ±12 anos. Os sintomas e sinais apresentaram maior proporção no grupo VHB+VHD (p=0,001). Para ambos os grupos, a maioria dos pacientes estava com AgHBe não reagente. O registro de alterações bioquímicas e hematológicas apresentou maior proporção no grupo VHB+VHD (p<0,05). Conclusão: O estudo revelou que os pacientes estavam em diferentes estágios clínicos da doença na consulta inicial para acompanhamento de condição crônica. O perfil clínico sugere maior gravidade da doença hepática entre os pacientes superinfectados por VHD.

High prevalence of occult hepatitis B virus genotype H infection among children with clinical hepatitis in west Mexico

Studies on the prevalence of infection with hepatitis B virus (HBV) among children are scarce in Latin American countries, especially in Mexico. This study was aimed to investigate the prevalence of HBV infection, occult hepatitis B infection (OBI) and HBV genotypes among children with clinical hepatitis. In total, 215 children with clinical hepatitis were evaluated for HBV infection. HBV serological markers and HBV DNA were analysed. OBI diagnosis and HBV genotyping was performed. HBV infection was found in 11.2% of children with clinical hepatitis. Among these HBV DNA positive-infected children, OBI was identified in 87.5% (n = 21/24) of the cases and 12.5% (n = 3/24) were positive for both HBV DNA and hepatitis B surface antigen. OBI was more frequent among children who had not been vaccinated against hepatitis B (p < 0.05) than in those who had been vaccinated. HBV genotype H was prevalent in 71% of the children followed by genotype G (8%) and genotype A (4%). In conclusion, OBI is common among Mexican children with clinical hepatitis and is associated with HBV genotype H. The results show the importance of the molecular diagnosis of HBV infection in Mexican paediatric patients with clinical hepatitis and emphasise the necessity of reinforcing hepatitis B vaccination in children.

Phylogenetic Analyses of HBV Pre-S/S Genes in Mother-Child Pairs with Long-Term Infection by Presumed Vertical Transmission

Vertical transmission from mother to child, the main route of chronic hepatitis B virus (HBV) infection in the East Asia, is considered one of the most important predictors for the response to antiviral therapies as well as its complications such as cirrhosis and hepatocellular carcinoma. Therefore, it is critical in both etiologic and prognostic aspects to confirm whether or not chronic HBV infection is acquired vertically. This study investigated whether mother-to-child infection could be proved by the phylogenetic analyses of HBV pre-S/S genes ever since several decades have elapsed in mother-child pairs with presumed vertical transmission. The pre-S and S regions of HBVs were compared and analyzed phylogenetically in a total of 36 adults (18 mother-child pairs) with chronic HBV infection. All of the isolates of HBV were genotype C and serotype adr. The divergence between mothers and offsprings was 0 to 1.5%. Phylogenetic trees revealed that 17 of 18 pairs (94%) with presumed vertical transmission were grouped into the same cluster. Vertical transmission from mother to child could be strongly suggested even in adults with a history of several decades of HBV infection using the phylogenetic analyses of pre-S and S genes.

Hepatitis B virus subgenotype C2- and B2-associated mutation patterns may be responsible for liver cirrhosis and hepatocellular carcinoma, respectively

The objective of this study was to examine hepatitis B virus (HBV) subgenotypes and mutations in enhancer II, basal core promoter, and precore regions of HBV in relation to risks of liver cirrhosis (LC) and hepatocellular carcinoma (HCC) in Southeast China. A case-control study was performed, including chronic hepatitis B (CHB; n=125), LC (n=120), and HCC (n=136). HBV was genotyped by multiplex polymerase chain reaction and subgenotyped by restriction fragment length polymorphism. HBV mutations were measured by DNA sequencing. HBV genotype C (68.2%) predominated and genotype B (30.2%) was the second most common. Of these, C2 (67.5%) was the most prevalent subgenotype, and B2 (30.2%) ranked second. Thirteen mutations with a frequency >5% were detected. Seven mutation patterns (C1653T, G1719T, G1730C, T1753C, A1762T, G1764A, and G1799C) were associated with C2, and four patterns (C1810T, A1846T, G1862T, and G1896A) were associated with B2. Six patterns (C1653T, G1730C, T1753C, A1762T, G1764A, and G1799C) were obviously associated with LC, and 10 patterns (C1653T, G1730C, T1753C, A1762T, G1764A, G1799C, C1810T, A1846T, G1862T, and G1896A) were significantly associated with HCC compared with CHB. Four patterns (C1810T, A1846T, G1862T, and G1896A) were significantly associated with HCC compared with LC. Multivariate regression analyses showed that HBV subgenotype C2 and C2-associated mutation patterns (C1653T, T1753C, A1762T, and G1764A) were independent risk factors for LC when CHB was the control, and that B2-associated mutation patterns (C1810T, A1846T, G1862T, and G1896A) were independent risk factors for HCC when LC was the control.

Molecular characterization of the hepatitis B virus in autochthonous and endogenous populations in the Western Brazilian Amazon / Caracterização molecular do vírus da hepatite B em população autóctone e população endógena do município de Lábrea, na Amazônia ocidental brasileira

INTRODUCTION: Hepatitis B virus (HBV) infection is a serious public health issue worldwide. Hepatitis B virus is classified into eight genotypes, varying from A to H, with distinct geographical distributions. In Brazil, the most frequent genotypes are A, D, and F. METHODS: This study aimed to characterize the HBV genotypes in cases of hepatitis B virus and hepatitis D virus (HDV) co-infections in an endemic area in the Western Brazilian Amazon. We analyzed 86 serum samples reactive for HBsAg from indigenous and non-indigenous populations obtained from previous serological surveys. RESULTS: Of the 86 reactive serum samples, 39 were found to be HBV-DNA-positive by semi-nested PCR. The genotypes were established by sequencing the amplified S gene region. We obtained 20 sequences classified into three genotypes: A, D, and F. Genotype A was the most frequent (60 percent), followed by D (35 percent) and F (5 percent). CONCLUSIONS: The distribution of the HBV genotypes reflected the pattern of historical occupation of the region.

INTRODUÇÃO: A infecção pelo vírus da hepatite B (VHB) é um importante problema de saúde pública no mundo. O VHB é classificado em oito genótipos diferentes, A-H, com distinta distribuição geográfica. No Brasil, os genótipos mais frequentes são o A, D e F. MÉTODOS: Objetivo deste estudo foi caracterizar os genótipos do VHB, em região endêmica de infecção pelos vírus da hepatite B e hepatite D (VHD), na Amazônia Ocidental Brasileira. Foram analisadas 86 amostras sororreativas para o HBsAg de indivíduos indígenas e não-indígenas, obtidas de inquéritos sorológicos realizados no município de Lábrea, Estado do Amazonas. RESULTADOS: Das 86 amostras sororreativas, 39 foram VHB-DNA positivas pela semi-nested PCR. Os genótipos foram estabelecidos pelo sequenciamento da região do gene S amplificado. Foram obtidas 20 sequências, classificadas em três genótipos A, D e F; sendo o genótipo A o mais frequente (60 por cento), seguido do D (35 por cento) e F (5 por cento). CONCLUSÕES: O perfil de distribuição dos genótipos encontrados do VHB reflete o padrão de ocupação histórica da região.

Seroprevalence of HBV and HCV markers among young adult males in the Air Force in Florianópolis, South Brazil

We investigated the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) serological markers of infection in young adults from the metropolitan region of Florianópolis who were conscripts of the Air Base of Florianópolis in the state of Santa Catarina, Brazil. A population-based cross-sectional seroprevalence study was conducted with 371 young males during a one year period starting in June 2009. Demographic characteristics, socio-economic characteristics and possible risk factors to HBV and HCV were assessed. Blood samples were analyzed for HBsAg, anti-HBc, anti-HCV and anti-HBs through automated microparticle enzymatic immunoassays (Abbott®, AxSYM System, Wiesbaden, Germany). None of the participants showed positivity to HBsAg or anti-HCV. The prevalence of anti-HBc was 1.6% (95% CI 0.6 - 3.5), and the prevalence of anti-HBs was 40.7% (95% CI 35.7 - 45.9). Unsafe sex was associated with positive anti-HBc in a bivariate analysis. There was a very low prevalence of past HBV infection and no cases of past HCV infection in a young adult population in the metropolitan region of Florianópolis. The very low prevalence of markers of infection and risk factors indicates a very optimistic future with respect to HBV and HCV infection in this population.

Este estudo teve como objetivo investigar a prevalência dos marcadores sorológicos de infecção pelo HBV e HCV em adultos jovens na Região Metropolitana de Florianópolis, conscritos da Base Aérea de Florianópolis, Santa Catarina, Brasil. Trata-se de um estudo soroepidemiológico transversal de base populacional com 371 adultos jovens, no período de um ano a partir de junho de 2009. Foram pesquisadas características sócio-econômicas e possíveis fatores de risco para HBV e HCV. As amostras de sangue foram analisadas quanto à presença de HBsAg, anti-HBc, anti-HCV e anti-HBs pelo método imunoensaio enzimático automatizado de micropartículas (Abbott®, Sistema AxSYM, Wiesbaden, Alemanha). Nenhum dos participantes demonstrou positividade para HBsAg ou anti-HCV. A prevalência do anti-HBc foi de 1,6% (IC 95% 0,6 - 3,5) e do anti-HBs foi 40,7% (IC 95% 35,7 - 45,9). Relação sexual desprotegida associou-se com a positividade do anti-HBc na análise bivariada. Demonstrou-se prevalência muito baixa de infecção passada pelo HBV e ausência de HCV nesta população de adultos jovens na Região Metropolitana de Florianópolis. A particularidade desta prevalência muito baixa de marcadores de infecção e fatores de risco aponta para um quadro otimista em relação ao HBV e HCV no futuro para esta população.

Hepatitis b: historia natural: manejo del niño portador asintomático / Hepatitis b: natural history: management of asymptomatic carrier child

La hepatitis B es aún un problema de salud pública a nivel mundial. Según datos del CDC el 42% de las hepatitis B crónicas del adulto han sido adquiridas durante la infancia. La historia natural de la infección crónica por el VHB se caracteriza por tres fases: inicial de tolerancia inmune al virus; de “clearence” inmune de variable duración, y de remisión. Durante la infancia y sobre todo la adolescencia más del 80% de los pacientes con VHB seroconvierten a antiHBe. La historia natural de la infección crónica actualmente puede ser modificada por la indicación del tratamiento apropiado el que, en un porcentaje de pacientes, evita la progresión de la enfermedad y sus secuelas.

Hepatitis b is still a public health problem worldwide. According to the CDC for 42% of adult chronic hepatitis B have been acquired during childhood. The natural history of chronic HBV infection is characterized by three phases: initial immune tolerance to the virus; “clearance” immune of variable duration, and referral. During childhood and adolescence, especially more tan 80% of patients seroconverted to HBV antiHBe. The natural history of chronic infection can now be modified by appropiate treatment indicating that, in a proportion of patients, prevents the progression of the disease and its sequelae.

Distribution of hepatitis B virus genotypes in Korea / 대한간학회지

BACKGROUND/AIMS: Considering the incidence of prevailing hepatitis B virus (HBV) genotypes in neighboring nations, the predominance of genotype C in Korea is exceptional and needs to be confirmed by nationwide investigation. METHODS: A total of 510 HBsAg (+) or HBeAg (+) serum samples was collected from subjects in several cities and harbors throughout the Korean peninsula for genotype (A-G)-specific multiplex PCR analysis. Another 40 serum samples from chronic HBV carriers from Iksan city were selected for sequencing of the entire HBV genome. Phylogenetic analysis was performed with 22 whole genomic sequences of Korean HBV strains enrolled in GenBank. RESULTS: An amplicon was found in 377 specimens and genotype C occupied 98.1% (370 cases); none of the other genotypes were found. A mixed pattern of genotypes B and C was seen in seven specimens (1.9%), of which five were tested using PCR targeting the X fragment; no genotype B bands were found. With the exception of 1 case, which was subgenotype A2, whole sequences of Korean HBV strains (n=62) belonged to subgenotype C2. CONCLUSIONS: The prevailing HBV genotype in Korea is C2; the other genotypes occur only rarely. Future studies should include confirmation of the detection of genotypes other than C.

Subgenotype and Serotype Analysis of Hepatitis B virus in Korean Chronic Hepatitis B Patients Under Treatment / 대한진단검사의학회지

BACKGROUND: Hepatitis B virus (HBV) detected in Korean patients almost belongs to genotype C, which is subdivided into subgenotype C1 (or Cs) and C2 (or Ce). It was recently reported that the risk of hepatocellular carcinoma is different between subgenotype C1 and C2. Thus, we studied the distribution of subgenotypes of HBV in Korean chronic hepatitis B (CHB) patients. METHODS: Specimens of 421 patients, who were diagnosed as CHB and underwent antiviral treatment, were used. After sequence analysis for HBV S gene, subgenotype was identified through phylogenetic analysis. Utilizing the same sequence data, the distribution of serotypes was also investigated. RESULTS: Among 421 patient specimens, genotype C was found in 419 (99.5%) and genotype B in 2 (0.5%). Among the genotype C strains, 417 strains were C2 subgenotype and 2 strains were mixed subgenotypes. However, C2 was evidently found even in the mixed sequences. Serotypes of 419 HBV with genotype C were classified as follows: adr, 385 (91.9%), adw, 22 (5.3%), ayr, 2 (0.4%) and mixed serotype, 10 (2.3%). Serotype of both HBV with genotype B was adw. CONCLUSIONS: It was found that HBV detected in Korean CHB patients under treatment almost all belong to the C2 (Ce) genotype.

Circulating genotypes of hepatitis B virus in Arunachal Pradesh.

BACKGROUND & OBJECTIVE: There is a paucity of information on distribution of hepatitis B genotypes from northeastern part of India. Arunachal Pradesh, one of the northeastern State of India bordering Bhutan, China and Myanmar, reported abnormally high numbers of hepatitis B surface antigen (HBsAg) positive cases in one of its districts during January-June 2005. We conducted this study in the subsequent months (August-December 2005) to know the prevalent genotypes by a rapid and specific method based on type-specific primers in Upper Dibang valley of Arunachal Pradesh. METHODS: A total of 438 randomly selected individual were screened for HBsAg positivity. Of the 93 HBsAg positive individuals, 36 HBsAg and HBV DNA positive samples were processed for HBV genotyping using type-specific primer based nested PCR (TSP-PCR). Representative samples were retested with RFLP-PCR based genotyping and nucleotide sequencing. RESULTS: Of the 36 samples, 29 (80.1%) could be genotyped by the TSP-PCR based method used. The predominant genotype was genotype A (41.6%) followed by genotypes C (27.8%) and D (11.1%). Seven isolates (19.9%) could not be genotyped by this method. INTERPRETATION & CONCLUSION: The presence of genotype C in this part of the country needs attention as genotype C takes a more aggressive disease course. Also, detection of genotype C in this isolated community bordering Tibet suggests viral gene flow from Tibet or other South-east Asian countries where genotype C of HBV is predominant.

Hepatitis B virus genetic diversity and mutant / 대한간학회지

Hepatitis B virus (HBV) is a partially double stranded DNA virus with genetic diversity represented by eight genotypes (A to H). Natural course and response to treatment could be affected by HBV genotypes. HBV shows high rates of turn over in the absence of proof-reading ability. As a result, large amounts of quasispecies are produced naturally or antiviral-associated. HBV consists of four open reading frames, namely preS/S gene, precore/core gene, polymerase gene, and X gene. Mutations on preS gene can result in undetectable HBsAg even in case that HBV is replicating. Surface gene mutation leads to decreased binding affinity to anti-HBs, which is associated with a vaccine escape mutant. Precore mutation abolishes HBeAg whereas mutations on basal core promoter gene down-regulate the HBeAg production. Mutations on basal core promoter are associated with increased HBV replication and high incidence of progressive liver diseases such as liver cirrhosis and hepatocellular carcinoma. Mutations on polymerase genes are often induced by antiviral therapy. Emergence of antiviral-resistant mutation is the major cause of treatment failure. Furthermore, existence of prior antiviral-resistant mutations limits the options of subsequent antiviral agents. Therefore, judicious use of antivirals and selection of the most potent drug with the lowest resistance rate are of the utmost importance for the prevention of antiviral-associated mutants. Detailed knowledge and understanding of HBV genetic diversity and mutant would be critical to establish strategies for the diagnosis and management of HBV infection.

Mutations in the S gene region of hepatitis B virus genotype D in Turkish patients.

The S gene region of the hepatitis B virus (HBV) is responsible for the expression of surface antigens and includes the 'a'-determinant region. Thus, mutation(s) in this region would afford HBV variants a distinct survival advantage, permitting the mutant virus to escape from the immune system. The aim of this study was to search for mutations of the S gene region in different patient groups infected with genotype D variants of HBV, and to analyse the biological significance of these mutations. Moreover, we investigated S gene mutation inductance among family members. Forty HBV-DNA-positive patients were determined among 132 hepatitis B surface antigen (HbsAg) carriers by the first stage of seminested PCR. Genotypes and subtypes were established by sequencing of the amplified S gene regions. Variants were compared with original sequences of these serotypes, and mutations were identified. All variants were designated as genotype D and subtype ayw3. Ten kinds of point mutations were identified within the S region. The highest rates of mutation were found in chronic hepatitis patients and their family members. The amino acid mutations 125 (M -> T) and 127 (T -> P) were found on the first loop of 'a'-determinant. The other consequence was mutation inductance in a family member. We found some mutations in the S gene region known to be stable and observed that some of these mutations affected S gene expression.

Hepatitis B virus genotype E detected in Brazil in an African patient who is a frequent traveler

Genotype E of hepatitis B virus (HBV) has not been described in Brazil and is found mainly in Africa. Genotype A is the most prevalent in Brazil, and genotypes B, C, D, and F have already been reported. We report here an HBV genotype E-infected patient and some characterization of surface (S) protein, DNA polymerase (P) and precore/core (preC/C) coding regions based on the viral genome. The patient is a 31-year-old black man with chronic hepatitis B who was born and raised in Angola. He has been followed by a hepatologist in São Paulo, Brazil, since November 2003, and he is a frequent traveler to Latin America, Africa, and Europe. In 2003, he was diagnosed with HBV infection and started treatment with lamivudine with the later addition of adefovir dipivoxil. No known risk factor was identified. Serologically, he is HBsAg and anti-HBe positive, but HBeAg and anti-HBs negative. DNA sequence analysis of the S/P region confirmed that this patient is infected with genotype E, subtype ayw4. The preC/C region showed G1896A and G1899A mutations but no mutations in the basal core promoter. Nucleotide substitutions common in genotype E were also observed (C1772, T1858 and A1757). Although this is not an autochthonous case and there is no evidence of further spread, the description of this case in Brazil highlights the current risk of viral genotypes spreading with unprecedented speed due to constant travel around the world.

A unique seroepidemiological pattern of HBV, HCV and HTLV-I in Nenets and Komi in northwestern Russia.

An epidemiological study of hepatitis viruses type B (HBV) and type C (HCV) and human T-cell leukemia virus type I (HTLV-I) was carried out among 105 residents (male:female=19:86) regarded as Nenets partly mixed with Komi, in the region of Krasnoe, the Nenets Autonomous District of the Arkhangelsk Region, in northwestern Russia in 2004. Blood was drawn from apparently healthy volunteers at ages of 41.6+/-16.5 (range 14-85) years. HBsAg, HBsAb, HBcAb, HBeAb and HCV Ab were measured by microparticle enzyme-immunoassay, and HTLV-I Ab was measured by particle agglutination. Prevalences of HBsAg(+), HBsAb(+), HBcAb(+) and HBeAb(+) were 0.0%, 29.5.%, 20.0% and 7.6%, respectively. The overall HBV infection rate (positive HBsAb or HBcAb) was 34.3%, while no positive HCV or HTLV-I Abs could be detected. A serological subgroup with positive HBsAb and negative HBcAb, consisting of 15(14.3%) females, contrasted sharply to other serological subgroups in sex, age, parent's ethnicity, positive HBeAb rate, and HBcAb inhibition%. We conclude that HBV is prevalent with unique serological patterns among the Nenets, while HCV and HTLV-I infections are negligible.

Genotypes of Hepatitis B Virus on Jeju Island / 대한간학회지

BACKGROUND/AIMS: Hepatitis B virus (HBV) was classified into 8 genotypes by a sequence divergence in the entire genome designated from A to H. HBV genotypes have distinct geographic distributions. Recently, HBV genotypes have been partially found as influencing the clinical manifestation of chronic liver disease in hosts. In Korea, the distribution of HBV genotypes remains unclear. The aim of this study was to evaluate the prevalence of the HBV genotype on Jeju Island. METHODS: Hepatitis B virus genotypes were evaluated among 107 hepatitis B carriers residing on Jeju Island. We used single PCR and multiplex-PCR assay with genotype-specific primer pairs for HBV genotypes A-F for the genotyping. RESULTS: 1. Fifty nine samples (55%) were positive for HBV DNA. The positivity was different according to the pattern of HBeAg/ anti-HBe expression, as -/-; 2/3 (66.7%), -/+; 30/73 (30%), +/-; 24/28 (85.7%) and +/+; 3/3 (100%). 2. In the single primer set of genotype-specific PCR, 59 samples (100%) were detected as genotype C and 2 (3%) were also detected as genotype A and B. 3. In multiplex-PCR, 58 samples (98%) were detected as genotype C and only one (2%) as a mixed pattern of genotype B and C. 4. When the PCR products were amplified with universal sense and genotype specific anti-sense from one genotype A, one B, and 2 C, all were included in genotype C. CONCLUSIONS: These results suggest that on Jeju Island, almost all HBV genotypes are C.

Reappraisal of HBV Genotypes and Clinical Significance in Koreans Using MALDI-TOF Mass Spectrometry / 대한간학회지

BACKGROUND/AIMS: Recent studies have shown that the genotype of hepatitis B virus (HBV) may correlate with the disease natural history and treatment outcome. However, several of these studies used low sensitivity assays in a small number of patients, and this has precluded an accurate evaluation of Korean HBV genotypes. We analyzed Korean HBV genotypes in a large population by employing a new technology, restriction fragment mass polymorphism (RFMP) using MALDI-TOF mass spectrometry, in a sensitive and specific manner. METHODS: Between February 1995 and December 2003, a total of 475 patients with chronic HBV infection were enrolled. The assay is based on the mass measurement of oligonucleotides having genotypic variations of the S gene. Clinical features including the virologic status and disease progression were also evaluated. RESULTS: The median age of the total patients was 35.5 years. Out of 475 patients, there were 162 (34.1%) inactive carriers, 172 (36.2%) had chronic hepatitis, 77 (16.2%) had liver cirrhosis and 64 (13.5%) had hepatocellular carcinoma (HCC). There were 454 patients (95.6%) with genotype C, 4 patients (0.8%) with genotype A, 16 patients (3.4%) with the mixed A and C genotype [7 patients (1.4%) with AA], and 1 patient (0.2%) with B genotype. Comparing genotype A and C, genotype A patients were all inactive carriers without HCC, whereas genotype C patients included those with chronic hepatitis, liver cirrhosis and HCC. CONCLUSIONS: HBV genotype C is highly prevalent in Korea. Although it is a small percentage, genotype A also exists and it seems to take a more benign clinical course than genotype C. Further studies are necessitated to assess the relationship between HBV genotypes and the various aspects of the diseases' clinical course.