Nosocomial Spread of Hepatitis B Virus in Two Hemodialysis Units, Investigated by Restriction Fragment Length Polymorphism Analysis

A method for genotyping hepatitis B virus (HBV) strains, based on restriction fragment length polymorphism (RFLP) analysis of four different amplified fragments of the HBV genome, was used to investigate nosocomial infections that occurred in two Brazilian hemodialysis centers. Viral isolates from hepatitis B surface antigen (HBsAg)-positive serum samples from 27 hemodialysis patients and 39 HBV-positive unrelated control patients were grouped according to their RFLP patterns. Strains isolated from the control patients were divided into nine RFLP patterns: A1, A2, A3 (genotype A), D1, D2, D3, D4 (genotype D), F1, and F2 (genotype F). In hemodialysis unit A (Rio de Janeiro), 14 HBV isolates were grouped into five different RFLP patterns: A1, A2, A3, D3, and D4. Pattern A2, present at a relatively low prevalence (18%) in the control group, was observed in the majority (53%) of the hemodialysis patients. Notably, all five patients who seroconverted to HBsAg positivity in 1995 carried the strain A2. In hemodialysis unit B (state of São Paulo), where an outbreak of HBV infection occurred in 1996–1997, RFLP analysis showed that all 13 patients who seroconverted were infected with HBV isolates of genotype D. Coinfection with strain A1 was detected in seven of them. The results demonstrate the value of RFLP analysis in establishing common sources of infection in hemodialysis centers.     

Eight genotypes (A-H) of hepatitis B virus infecting patients from San Francisco and their demographic, clinical, and virological characteristics

Clinical lines of evidence have been accumulated that hepatitis B virus (HBV) genotypes have characteristic geographical distributions and distinct clinical impact on liver diseases. The distribution of HBV genotypes was determined with reference to hepatitis B e antigen (HBeAg) and alanine aminotransferase (ALT) levels in 165 patients with hepatitis B in San Francisco. HBV genotypes were determined by enzyme-linked immunosorbent assay (ELISA) and the unclassified samples were sequenced within the S region for phylogenetic analysis. Genotype A occurred in 60 (36%) patients, B in 16 (10%), C in 56 (34%), D in 19 (12%), E in 1 (1%), F in 1 (1%), G in 8 (5%), and H in 4 (2%). Caucasians were infected predominantly with HBV genotype A (HBV/A) (38 of 57 [67%]), Asians with HBV/C (45 of 63 [71%]), and Hispanics with HBV/F and HBV/H (4 of 9 [44%]). Serum ALT levels were higher in the patients infected with HBV/A (P = 0.03) or HBV/G (P = 0.02) than HBV/C. HBeAg was more frequent in patients infected with HBV/G than HBV/C or HBV/D (7 of 8 [88%] vs. 25 of 56 [45%] or 6 of 19 [32%], P = 0.03 or 0.01). In conclusion, eight genotypes (A-H) were identified in San Francisco in association with various ethnicities and then influenced ALT levels as well as the prevalence of serum HBeAg. HBV genotype H might be identified by combination of preS2 serotpe bksf and HBsAg serotype adw.     

Molecular epidemiology of hepatitis B virus in Spain: identification of viral genotypes and prediction of antigenic subtypes by limited sequencing

The hepatitis B virus (HBV) genotypes were studied by a line probe assay (LiPA) and by direct sequencing of a 339 nucleotide fragment from the S region of the viral genome in samples from 269 carriers living in Spain, either native to Spain (231) or immigrants from Africa, Asia, and Eastern Europe (38). The sequences were also used to predict the HBV surface antigen (HBsAg) subtype on the basis of the amino acids specified at selected positions of the HBsAg molecule. Agreement between the two genotyping methods was found in most cases (98.1%) and a HBV genotype could be assigned to all samples. The viral groups D/ayw2 (30.1%), D/ayw3 (28.6%), and A/adw2 (21.2%) were prevalent, with an additional participation of the groups D/ayw4 (4.8%), F/adw4q- (1.9%), A/ayw1 (1.9%), and D/adw3 (0.7%), all of them present among the autochthonous carriers. Strains from genotypes B and C were found exclusively among Chinese immigrants. Genotype E strains were found in immigrants from Central Africa and in one patient native of Spain. Point mutations leading to amino acid changes of residues involved in the expression of the HBsAg subtype determinants were found in 12 samples (4.5%). Some mutations would predict the putative novel genotype-subtype associations A/adw4q+, A/ayr, D/ayr, and E/ayw1, while others would suggest the loss of subtype-specific determinants. The finding of HBV strains characteristic for Africa among the autochthonous carriers confirms the emergence of African HBV strains in Spain.     

Antigenic Diversity of Hepatitis B Virus Strains of Genotype F in Amerindians and Other Population Groups from Venezuela

The adw4 subtype of hepatitis B virus (HBV) belongs to a unique genomic group (genotype F) representing the original HBV strains from the New World. Data regarding the prevalence of this subtype among HBV carriers in South America are, however, scarce, and those concerning HBV genotype F are based on only a few samples from Latin America. In this study, serum samples were obtained from 141 hepatitis B surface antigen (HBsAg) carriers from Amerindians and urban populations from Venezuela. The HBsAg subtype was identified with monoclonal antibodies in 105 samples, and the HBV genotype was identified by reverse-phase hybridization with DNA fragments in 58 samples. The adw4 subtype was highly prevalent in the population studied (75%); among the Amerindians, the prevalence was 97%. The adw2 subtype was also present (10%), while other subtypes (ayw3 and ayw4) were only occasionally found. The HBV subtype was associated with the expected genotype in most cases (80%), and thus genotype F was highly prevalent. Sequencing of viral strains that gave genotypes unpredicted by the HBsAg subtyping confirmed seven of them as belonging to not previously described genotype-subtype associations: namely, adw2 and ayw4 within genotype F.     

Distribution of HBV genotypes and mutants among hepatitis B infected patients from northern Poland

Hepatitis B virus (HBV) infection is one of the major global epidemiological problems. The aim of our study was to determine the distribution of HBV genotypes in Poland since the data concerning the spread of HBV viruses in the central-eastern region of Europe is still very limited. HBV DNA was extracted from 58 serum samples. To quantify the level of HBV DNA the Roche Amplicor HBV Monitor Assay was used. To genotype and assign HBV subtypes DNA sequencing methods were performed. The HBV virus from 43 serum samples from hepatitis B infected patients was genotype A (74.1%), 12 cases had genotype D (20.7%), and 3 had the rare in Europe genotype F (5.2%). Prediction of HBV serological subtypes based on HBsAg sequencing showed almost 100% occurrence of subtype adw2 in the group of genotype A samples, three different subtypes in genotype D (ayw2, ayw3, and ayw4), and equal distribution of subtype adw4q- in all 3 cases of genotype F, also the most prevalent subtype in the Amerindians. Our results coincide with the general European HBV prevalence. However, HBV genotype F, which is not a common genotype in European countries, was detected and so was relatively high occurrence of genotype D, which may reflect historical and ethnical migration events in Poland in the past.     

云南省乙型肝炎病毒基因型和血清型的流行状况分析

目的了解云南省人群中流行的乙型肝炎病毒（Hepatitis B virus,HBV）基因型和血清型分布情况。方法从参加健康体检的人群中筛查HBsAg阳性的血清标本,利用巢式PCR扩增HBVS基因片段,并对扩增产物进行序列测定,从GenBank中查获A～I基因型共27株HBV参考序列,构建HBVS基因系统发生树,以此确定其样本的基因型及血清型,并对结果进行统计分析。结果从2216名体检人员血清标本中筛查出39份HBsAg阳性的样本,HBV的s基因序列分型结果表明有4种基因型：c型占76．9％,B型占15．4％;D型占5．1％;I型占2．5％。血清分型结果为：adw2型占71．8％;adrq‘型占17．9％;ayr型占10．3％。所有adw2血清型标本均为c基因型。HBsAg、HBeAg双阳性标本中75％为c基因型／adw2血清亚型。结论云南省HBV感染人群中HBV基因型的分布以C型为主,血清型以adw2型为主。     

云南省乙型肝炎病毒基因型和血清型的流行状况分析

目的 了解云南省人群中流行的乙型肝炎病毒(Hepatitis B virus,HBV)基因型和血清型分布情况.方法 从参加健康体检的人群中筛查HBsAg阳性的血清标本,利用巢式PCR扩增HBV S基因片段,并对扩增产物进行序列测定.从GenBank中查获A～I基因型共27株HBV参考序列,构建HBV S基因系统发生树,以此确定其样本的基因型及血清型,并对结果进行统计分析.结果 从2216名体检人员血清标本中筛查出 39份HBsAg阳性的样本,HBV的S基因序列分型结果表明有4种基因型:C型占76.9%,B型占15.4%;D型占5.1%;I型占2.5%.血清分型结果为:adw2型占71.8%;adrq+型占17.9%;ayt型占10.3%.所有adw2血清型标本均为C基因型.HBsAg、HBeAg双阳性标本中75%为C基因型/adw2血清亚型.结论 云南省HBV感染人群中HBV基因型的分布以C型为主,血清型以adw2型为主.     

云南省乙型肝炎病毒基因型和血清型的流行状况分析

目的 了解云南省人群中流行的乙型肝炎病毒(Hepatitis B virus,HBV)基因型和血清型分布情况.方法 从参加健康体检的人群中筛查HBsAg阳性的血清标本,利用巢式PCR扩增HBV S基因片段,并对扩增产物进行序列测定.从GenBank中查获A～I基因型共27株HBV参考序列,构建HBV S基因系统发生树,以此确定其样本的基因型及血清型,并对结果进行统计分析.结果 从2216名体检人员血清标本中筛查出 39份HBsAg阳性的样本,HBV的S基因序列分型结果表明有4种基因型:C型占76.9%,B型占15.4%;D型占5.1%;I型占2.5%.血清分型结果为:adw2型占71.8%;adrq+型占17.9%;ayt型占10.3%.所有adw2血清型标本均为C基因型.HBsAg、HBeAg双阳性标本中75%为C基因型/adw2血清亚型.结论 云南省HBV感染人群中HBV基因型的分布以C型为主,血清型以adw2型为主.     

Hepatitis B virus in Mar del Plata,Argentina: Genomic characterization and evolutionary analysis of subgenotype F1b

The aim is to describe the molecular epidemiology and perform a genomic characterization of hepatitis B virus (HBV) circulating in Mar del Plata and to identify the origin and diversification patterns of the most prevalent genotype. The S gene and the region encompassing the X gene, basal core promoter (BCP), and precore (preC) was analyzed in 56 samples. They were genotyped as: 80% F1b, 9% A2, 7% D3, and 2% D1. A recombinant F4/D2 genome was detected. The double substitution G1764A/A1762T at the BCP (reduced HBeAg expression) was found in 20% F1b, 2% A2, 2% D1, and 2% D3 samples. A unique D3 presented the G1896A substitution at the preC (HBeAg negative phenotype). A 13% of the samples showed mutations at the HBsAg “a” immunodeterminant (escape from neutralizing antibodies). Mutations at the polymerase (antiviral resistance) were found in 52% of the samples. Coalescent analysis of subgenotype F1b, the most prevalent in the city, showed that viral diversification in Mar del Plata started by year 2000. F1b was the most prevalent genotype detected, being a characteristic of actual HBV infections in Mar del Plata. Local HBV exhibit clinically relevant mutations, but a minority of them was shown to be associated to potential vaccination escape or antiviral resistance. Nevertheless, further studies are needed to determine whether any of these mutants could pose a threat to prevention, diagnosis, or treatment.     

Hepatitis B virus genotypes and HBsAg subtypes in refugees and injection drug users in the United States determined by LiPA and monoclonal EIA.

Hepatitis B virus (HBV) genotyping and hepatitis B surface antigen (HBsAg) subtyping were carried out on sera from 196 HBsAg-positive patients, including 151 refugees entering the United States and 45 injection drug users in Seattle. HBsAg subtyping was performed by enzyme immunoassay (EIA) using a panel of monoclonal antibodies and the HBV genotype was determined by polymerase chain reaction (PCR) followed by detection of amplified HBV DNA by a reverse-phase hybridization line probe assay (LiPA) using genotype-specific probes. HBV DNA was detected by PCR in 155 (79%) of the 196 sera and all 155 were genotyped by LiPA. Samples from Southeast Asia were predominantly genotype B/subtype ayw1 and genotype C/adr; samples from the former Soviet Union and eastern Europe were mostly genotype D/ayw2 and genotype D/ayw3; samples from east Africa were mainly genotype A/adw2 and genotype D/ayw2; and samples from injection drug users were mostly genotype D/ayw3 and genotype A/adw2. Some strains of ayw3 gave atypical monoclonal antibody reactivity patterns in the subtyping assay due to a Val/Ala instead of a Thr at amino acid residue 118 and a Thr instead of a Met at residue 125. A strain of ayw2 also gave an atypical monoclonal antibody reactivity pattern due to an Ala instead of a Thr at amino acid residue 123. LiPA genotyping and monoclonal EIA subtyping can provide useful information for epidemiological studies.     

Clinical and Virological Aspects of Blood Donors Infected with Hepatitis B Virus Genotypes B and C

Pathogenic and therapeutic differences among hepatitis B virus (HBV) genotypes have been documented. However, the association of virological characteristics with clinical differences among HBV genotypes remains unclear. We therefore studied the clinical and virological characteristics of Taiwanese volunteer blood donors infected with HBV genotypes B and C. HBV genotypes were determined in 300 candidate blood donors positive for HBV surface antigen (HBsAg), and sequences of the precore gene of the HBV genome were determined in 50 HBV e antigen (HBeAg)-positive and 50 HBeAg-negative blood donors. Of 300 HBsAg-positive blood donors, 10% had elevated serum aminotransferase levels and 27% were positive for HBeAg. HBV genotype distribution in 264 viremic carriers was as follows: B, 221 (83.7%); C, 39 (14.8%); F, 1 (0.4%); and mixed infection, 3 (1.1%). Blood donors with genotype C infection tended to have a higher frequency of HBeAg positivity and a higher serum HBV DNA level than those with genotype B infection. The frequency of precore stop codon mutation was significantly higher in HBeAg-negative blood donors than HBeAg-positive ones, irrespective of HBV genotypes. Meanwhile, only 5% of blood donors with genotype C infection had C-1858 strains. In conclusion, mixed infection of HBV genotypes indeed occurs, and genotype C has a higher serum HBV DNA level than genotype B. Precore stop codon mutation is common in HBeAg-negative HBV carriers, irrespective of HBV genotypes. In contrast, precore C-1858 strains are rarely identified in Taiwanese HBV genotype C.     

Strong association between genotype F and hepatitis B virus (HBV) e antigen-negative variants among HBV-infected argentinean blood donors

A number of reports have indicated an increased risk of cirrhosis and hepatocellular carcinoma in hepatitis B virus (HBV)-infected individuals carrying HBV e antigen (HBeAg)-negative variants. Although distinct core promoter and precore mutations distributed according to geographical locality and viral genotype have been reported, epidemiological data from South America are still scarce. The prevalences of HBV genotypes and core promoter and precore polymorphisms in 75 HBeAg-negative Argentinean blood donors were surveyed. The observed frequencies of HBV genotypes were 64.0% for genotype F, 17.3% each for genotypes A and D, and 1.3% for genotype C. Genotype F strains were widely distributed and significantly more prevalent in the northern region of the country (P < 0.001). An overall high proportion of a stop codon mutation (UAG) at precore codon 28 (66.7%) was observed. Wild-type codon 28 (UGG) was present in 29.3% of the samples, and the remaining 4.0% of samples had mixed variants. The combination of A at nucleotide (nt) 1762 and G at nt 1764 of the core promoter was found in 58.7% of the samples. The variant profiles--T at nt 1762 and A at nt 1764 or A at nt 1762 and A at nt 1764--were detected in 28.0 and 1.3% of the samples, respectively. The observed core promoter polymorphisms could not be related to the ratio of HBeAg to anti-HBeAg antibody, HBV genotype, or precore codon 28 status. Nevertheless, a clear association of genotype F and a precore stop codon mutation was found (P < 0.05). In conclusion, HBV genotype F and mutant codon 28 strains predominated and were strongly associated in a geographically broad Argentinean blood donor population.     

Prevalence of hepatitis B virus and risk factors in Brazilian non‐injecting drug users

Non‐injecting drug users are at high‐risk for acquiring hepatitis B virus (HBV), although the factors contributing to this increased risk are not known. In the present study, the overall and occult HBV infection prevalence rates were determined in a large population of non‐injecting drug users in the Central‐West region of Brazil. HBV genotypes and predictors of infection were also identified. A total of 852 individuals in 34 drug treatment centers were interviewed, and their serum samples were tested for the presence of HBV markers by ELISA. HBsAg and anti‐HBc‐positive samples were tested for HBV DNA by PCR. Samples with HBV DNA were genotyped by restriction fragment length polymorphism (RFLP). The overall prevalence of HBV infection was 14% (95% CI: 11.7–16.5). A multivariate analysis of risk factors showed that age >30 years, non‐white race/ethnicity, duration of drug use >10 years, lifetime number of sexual partners >10, non‐use of condoms, and HCV and HIV status were associated significantly with HBV infection. Of the 9 (1%) HBsAg‐reactive samples, HBV DNA was present in 2/2 of HBeAg‐positive and in 5/7 anti‐HBe‐positive samples. An occult HBV infection rate of 2.7% (3/110) was found among anti‐HBc‐positive individuals. All HBV DNA‐positive samples were genotyped: seven were genotype A, two were genotype D, and one was genotype F. Finally, few individuals (8%) had serological evidence of a previous HBV vaccination. These findings indicate that preventive interventions are needed for both sexual and drug‐related high‐risk behavior. Additionally, non‐injecting drug users should be targeted for HBV vaccination. J. Med. Virol. 81:602–609, 2009 © 2009 Wiley‐Liss, Inc.     

Molecular epidemiological study of hepatitis B virus in blood donors from five Chinese blood centers

Although the genetic variability of hepatitis B virus (HBV) in HBV-infected patients has been extensively studied, reports on genotypes, subtypes and mutations in the S region of HBV strains from Chinese blood donors are limited. In this study, 245 blood samples from HBsAg-positive blood donors were collected from five geographically diverse blood centers in China. The S region of HBV was amplified, and the HBV genotype and subtype were determined. The amino acid sequences of the S region were aligned, and mutations related to the failure of immunization and HBsAg detection were determined. Of the 245 samples, 228 (93?%) were genotyped successfully. We found that genotypes B, C, D and A accounted for 58.8?%, 21.9?%, 6.6?% and 3.95?% of the isolates, respectively. The distribution of HBV antigen subtypes was as follows: adw (67.6?%), adr (23.3?%) and ayw (8.7?%). Mutations were present in 39 (17.1?%) of 228 samples in the major hydrophilic region (MHR) of the S region. This study demonstrated that HBV genotype/subtype B/adw was the most frequent strain circulating in HBV-infected Chinese blood donors, followed by C/adr. The occurrence of MHR mutants in HBV-infected blood donors and the potential failure to detect some of them in collected units poses a threat to transfusion safety.     

Distribution of hepatitis B virus (HBV) genotypes among HBV carriers in the Cote d'Ivoire: complete genome sequence and phylogenetic relatedness of HBV genotype E

The characteristics of hepatitis B virus (HBV) genotype E are not well known because only a few studies have been carried out by complete genome analysis. The aim of this study was to elucidate the distribution of HBV genotypes in Cote d'Ivoire, and to clarify the genotype-related characteristics of genotype E. The distribution of HBV genotypes among 48 HBV carriers in Cote d'Ivoire was determined using serological and genetic methods. The characteristics of genotype E were evaluated by complete genome sequences, and further investigations of small S gene, basic core promoter (BCP) mutation, and precore mutation were undertaken. HBV genotype distribution among the 48 carriers was 6.3% for genotype A, 6.3% for genotype D, and 87.4% for genotype E. Complete genomes of two genotype E strains were sequenced, and found to have 98.2% to 99.2% homology at the nucleotide level when compared with genotype E strains reported previously. In 24 genotype E carriers, the precore mutation was detected in 75% of the patients without HBeAg, in contrast to only 25% of the patients with HBeAg (P < 0.05). All 24 strains have T at nucleotide 1858 in the precore region. In contrast, BCP double mutation was detected in 17% of the patients with HBeAg, and 33% of the patients without HBeAg. These results indicated as the following: (1) genotypes A, D, and E of HBV exist in Cote d'Ivoire and genotype E is the most prevalent; (2) genotype E spread with low genetic diversity over the complete genome in West Africa; (3) HBV precore and/or BCP double variants were common among the patients with genotype E infections.     

'Hbe minus' mutants of hepatitis B virus. Molecular characterization and its relation to viral genotypes

The precore-core and S genes of HBV were directly sequenced from serum samples of 42 patients with chronic hepatitis B (16 hepatitis Be antigen [HBeAg]+and 26 anti-HBe+). Viral genotype A was identified in 12 cases, genotype D in 11 and genotype F in 19 cases. Precore mutations, mainly M1 (G1896A, stop at codon 28) were similarly found among viral genotypes A and D: seven cases (58%) and six cases (55%), respectively. The selection of M1 mutants from genotype D resulted in a more stable encapsidation signal but was less stable for genotype A precore mutants. Oddly enough, the encapsidation signal of M1 precore mutants from genotype F sequences were evenly distributed among less stable (genotype A M1 mutants) and more stable encapsidation signal (genotype D M1 mutants). This study shows that the selection of precore mutants that preclude the HBeAg expression, including the M1 mutation, does not necessarily depend on the stabilization of the encapsidation signal or the viral genotype In addition, the particular behavior of genotype F genomes at precore region is described.     

Genotypes and S-gene variability of Mexican hepatitis B virus strains

The genotypes and subtypes of 15 Mexican hepatitis B virus strains were determined by sequencing and phylogenetic analysis of the small S-gene. The most predominant strains were found to be divergent genotype/subtype F/adw4 strains (66.6%), followed by A/adw2 (20.0%), D/ayw3 (6.7%), and G/adw2 (6.7%). The S-genes of the Mexican genotype F strains and two Nicaraguan strains described previously formed a subcluster with more than 4% divergence from the other strains within this genotype. The Mexican strains within genotypes A and D showed the highest homology with strains from Europe and the United States. Ten amino acid substitutions not described previously were found in the S-genes of strains from nine chronic carriers, whereas the S gene in strains from six acute hepatitis B patients were highly conserved as compared to their respective genotypes. One genotype F strain from an HBsAg positive chronic carrier had a T to A mutation at position 647, forming a translational stop at codon 216. Two genotype F strains from HBsAg negative chronic carriers had a Val180 instead of an Ala found in the other genotype F strains. This study shows that a divergent genotype F predominates in Mexican strains analyzed, which presented amino acid substitutions not reported previously outside the a determinant.     

Viral genotypes and response to interferon in patients with acute prolonged hepatitis B virus infection of adulthood in Japan

Acute hepatitis B virus (HBV) infection was diagnosed in 57 adults admitted to Toranomon Hospital in Tokyo, Japan. Genotypes of HBV were determined by a serological method and compared to those in 1,077 patients with chronic hepatitis B. The distribution of genotypes were: genotype A (acute, 22.8% vs. chronic, 1.9%; P < 0.00001); B (14.0% vs. 9.4%); C (43.9% vs. 87.7%, P = 0.004); D (1.8% vs. 0.2%); F (1.8% vs. 0.2%); and unable to be typed (15.8% vs. 0.6%, P = 0.001). The infection persisted in seven (12%) of them. They included six (86%) of the seven patients who received prednisolone or glycyrrhizin during an acute phase of illness and one of the 41 (2%) who did not (P = 0.01). Interferon was given to the seven patients with acute prolonged HBV infection, and four of them responded by clearing hepatitis B e antigen (HBeAg) and surface antigen (HBsAg) from serum. Of the four responders, one was infected with HBV genotype B and three with genotype C. HBsAg persisted in the remaining three patients all of whom were infected with HBV genotype A, and HBeAg stayed positive in one of them. These results indicate that HBV genotype A prevails in Japanese patients with acute hepatitis B, and suggest a high efficacy of interferon in the adult patients with acute prolonged HBV infection, except in those infected with HBV genotype A.     

Genotype F prevails in HBV infected patients of Hispanic origin in Central America and may carry the precore stop mutant

The distribution of HBV genotypes and the presence of the precore stop mutation were investigated in HBV strains from Central America. 333 HBsAg positive sera from chronic HBsAg carriers and acute hepatitis B cases from five different countries (Costa Rica, Nicaragua, Honduras, El Salvador and Guatemala) were tested for HBV DNA by nested PCR. Genotyping by limited sequencing within the S gene was performed on 90 strains, 66 from sera with a high level of HBV DNA, and another 24 from sera positive for HBV DNA only after nested PCR. 23 of the samples were anti-HBe positive. Genotype F was found in 71 (79%), A in 13 (14%), D in 5 (6%) and C in one of the 90 sera. 18 patients with genotype F infection had anti-HBe and HBV DNA in serum. Since the three published precore sequences of genotype F strains have a C¹⁸⁵⁸, which is known to prevent the precore stop mutation from G to A at position 1896, the precore and part of the core genes were sequenced from 19 anti-HBe positive sera with HBV DNA, 17 with genotype F and 2 with genotype A. The A¹⁸⁹⁶ mutation was found in 11 of the 17 genotype F strains. All these had a T¹⁸⁵⁸, which was also present in 5 of the 6 genotype F strains with G¹⁸⁹⁶. The precore region was therefore sequenced from genotype F strains from 5 HBeAg positive sera from the five different Central American countries. These also had a T¹⁸⁵⁸, which thus is the wild type substitution in genotype F in Central America. A number of mutations were recorded between residues 57 and 68 in the core protein corresponding to a unique clustering region of the genotype F strains. The predominance of genotype F in Central American populations of Hispanic origin was not anticipated since this genotype is regarded as indigenous to the Amerindian populations of the New World. J. Med. Virol. 51:305–312, 1997. © 1997 Wiley-Liss, Inc.     

High prevalence of mixed genotype infections in hepatitis B virus infected intravenous drug users

The clinical relevance of hepatitis B virus (HBV) genotypes has been documented; however, the prevalence of mixed HBV genotype infections in at-risk groups remains controversial. The HBV genotypes were determined in 325 HBV-infected intravenous drug users (IVDU) who were at a greater risk of multiple exposures to different HBV genotypes by using a newly developed line probe assay. The distribution of HBV genotype was as follows: genotype A alone in 2 (0.6%); genotype B alone in 256 (78.8%); genotype C alone in 10 (3.1%); mixed genotype A and B in 18 (5.5%); genotype B and C in 30 (9.2%); genotype B and D in 1 (0.3%); genotype A and C in 1 (0.3%); and mixed infections of genotype A, B, and C in 3 (0.9%). Clonal analysis confirmed further the existence of mixed genotype infection and recombination between different genotypes. Compared with our previous data, the line probe assay seemed more sensitive than polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay in identifying HBV genotype (98.8% vs. 65.0%) and detecting mixed genotype infections (16.3% vs. 0%). In conclusion, the prevalence of mixed HBV infections is substantially higher in IVDU in endemic areas, and the line probe assay is a useful method for rapid genotyping of HBV, with particular reference to the detection of mixed genotype infections.