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, EI 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.

High prevalence of GB virus C strains genetically related to strains with Asian origin in Nicaraguan hemophiliacs

The presence of hepatitis GB virus C (GBV-C), also known as hepatitis G virus (HGV), and hepatitis C virus (HCV) were investigated in sera from 45 hemophiliacs from nine locations in Nicaragua using a nested polymerase chain reaction (PCR). Primers used to detect GBV-C and HCV derived from the helicase region and 5'UTR, respectively. Seventeen (38%) patients were positive for GBV-C RNA in serum by PCR. Twelve (27%) patients were positive for HCV RNA by PCR. Six (13%) of these were coinfected with GBV-C. Anti-HCV was detected in all the 12 HCV RNA positive hemophiliacs and in another 14 (31%) individuals, in whom GBV-C RNA was found in 2. Ten patients (22%) lacked markers for both GBV-C and HCV. The mean age of the patients positive for GBV-C but negative for HCV by PCR was significantly lower than for those negative for GBV-C but positive for HCV by PCR (P < 0.05; Student's t-test), indicating that the risk for this group of hemophiliacs to acquire GBV-C infection is higher as compared to the risk of acquiring HCV infection. Eleven GBV-C strains were sequenced in the 5'UTR. Sequence comparison to previously published GBV-C strains revealed that all 11 strains were more similar to Asian strains than to strains of European and African origin. Sequences in the NS5-B region were available for 8 HCV strains, all of which were found to belong to genotype 1a. The similarity of the Nicaraguan GBV-C strains to strains from Asia indicates that the GBV-C strains in the region presumably have an Amerindian origin. It is also considered that the HTLV II strains in the New World aboriginal populations are ancient and brought there by the ancestral Amerindian populations from Asia. Further, the genotype F of hepatitis B virus, known to represent the strains in populations with Amerindian background, predominates in Central American populations with Hispanic background. It remains to be clarified why Amerindian strains of GBV-C as well as of HBV predominate also in populations with mixed ethnic background in Central America.

Interferon-alpha 2b treatment in hepatitis B carriers. Effect on hepatitis B virus DNA levels in children infected with different genotypes

Eleven hepatitis B virus (HBV) carrier children, infected with genotypes A-D, were treated with interferon-alpha. Two children had a sustained loss of hepatitis B e-antigen and HBV DNA. They were infected with the non-Asian genotypes A and D, and had low HBV DNA and high ALT levels in serum before treatment. However, HBV DNA titres decreased during treatment also in children infected with the East-Asian genotypes B and C.

Genetic relatedness of Sindbis virus strains from Europe, Middle East, and Africa

The relatedness of 40 strains of Sindbis virus (SIN) from Europe, the Middle East, and Africa was investigated by limited sequencing within the gene encoding the E2 glycoprotein corresponding to amino acid residues 117 to 229 and encompassing one of the major neutralization epitopes. Phylogenetic analyses using distance matrix and parsimonious methods identified two major genetic clusters of western SIN strains, although the variability was less than that of the corresponding region for Venezuelan equine encephalomyelitis virus with a maximum divergence of 12.4% versus 28.5%, respectively. One cluster comprising 19 strains included the HR derivate of the Egypt SIN prototype, AR339, and strains from Israel, Saudi-Arabia, Italy, Slovak Republic, Azerbaijan, as well as three Swedish strains. Another cluster of 17 strains included the Ockelbo virus (OCK) prototype, Edsbyn 5/82, and the majority of SIN strains from northern Europe including strains from Sweden, Norway, and Karelia, as well as two strains from South Africa. A third cluster, supported by the Neighbor joining method, was made up of four strains from South Africa, Uganda, and Cameroon. Residue 212, either Ser or Thr, previously appointed important for the differences in neutralization assays between SIN and Edsbyn 5/82, respectively, correlated with the two major genetic clusters, but was a Thr for two of the three Swedish strains in the SIN prototype cluster, and a Ser in one Swedish and one Karelian strain in the OCK cluster. The finding of strains similar to prototype SIN in Middle Sweden and of strains in South Africa relating to the northern cluster of SIN strains supports the notion of the dispersal of SIN by migrating birds as previously suggested for New World alphaviruses.

Complete sequencing of a gibbon hepatitis B virus genome reveals a unique genotype distantly related to the chimpanzee hepatitis B virus

We have sequenced the complete genome of a hepatitis B virus (HBV) strain that was transmitted from a gibbon with chronic hepatitis B to a chimpanzee that subsequently developed acute hepatitis B. The genome was 3,182 nucleotides long and had a genetic organization identical to and including the characteristics of other mammalian hepadnaviruses. Thus, the regulatory elements, the direct repeats, and the four open reading frames (ORFs) of this virus were all maintained, although there were amino acid substitutions affecting all the ORFs. Within the S gene encoding for the hepatitis B surface antigen (HBsAg), the subtype could be deduced as ayw3 in accordance with previous serological results. There were 25 amino acid substitutions affecting the P gene, 12 of which were within the spacer region. This region, which was the most divergent part of the genome compared to other HBV strains, also encodes for the pre-S proteins. A comparison with sequences of other hepadnaviruses revealed that the genome of gibbon HBV was unique as compared to previously described HBV genotypes. It was most similar to the chimpanzee HBV strain with which it shared 90.3% nucleic acid homology at the level of the complete genome and 96.3% homology at the level of the S-gene region corresponding to HBsAg, although being a distinct genotype as compared to the latter virus. Analyses performed using five different algorithms for phylogenetic tree construction showed more than 99% bootstrap support for the gibbon and the chimpanzee HBV to be grouped within the human HBV strains and that they represented later offshoots than the HBV strains of genotype F. However, in most of the dendrograms both the gibbon and the chimpanzee strains represented early lineages, indicating that these viruses are indigenous to their respective hosts and not recent acquisitions from man.

Nosocomial spread of hepatitis B virus (HBV) in a haemodialysis unit confirmed by HBV DNA sequencing

An outbreak of hepatitis B virus (HBV) infection in a haemodialysis unit is described. Four patients in the unit contracted subclinical HBV infection within three months. DNA sequence analysis of the S gene of HBV isolates from chronic carriers and newly infected patients in the unit aided in tracing possible transmission pathways. Three newly infected patients had received partial or complete HBV vaccination previously. HBV was rapidly cleared from all three although the anti-HBs titre had not reached 10 IU L-1 in any of them at the time of infection.

Subtypes, genotypes and molecular epidemiology of the hepatitis B virus as reflected by sequence variability of the S-gene

The serologic heterogeneity of the hepatitis B virus (HBV) has been established from immunodiffusion experiments for a long time. Four serotypes called subtypes of the hepatitis B surface antigen (HBsAg) have been defined by two mutually exclusive determinant pairs, d/y and w/r, and a common determinant a. These subtypes are adw, ayw, adr and ayr. By subdivision of the four major subtypes in the mid-70s, nine different subtypes were identified. Sequencing of viral genomes has now become a major goal of descriptive virology, and sequence data is now used to trace routes of infection, to reconstruct the phylogenetic history of viruses and two delimit genetic subtypes. A genetic classification based on the comparison of complete genomes has defined four genomic groups of HBV, later referred upon as genotypes, which were designated with A-D. However, the interrelation of the nine subtypes to the genotypes, the possible presence of more than four human HBV genotypes as well as their global geographical prevalence remained to be determined. By sequencing the S-gene of HBV the molecular basis was assessed for the serological variations of HBsAg within the major four subtypes. Thereby, also two new genotypes of HBV designated with E and F were identified. Complete genomic sequencing of E and F strains confirmed their status as new genotypes. The F genotype was found to diverge from other HBV genomes sequenced by 14%, thus being the most divergent HBV genome so far characterized. When the worldwide molecular epidemiology of HBV based on the variability of the S-gene was defined, the E and F strains seemed to originate in aboriginal populations of Africa and the New World, respectively. They shared a unique substitution at residue 140 in the second immunodominant loop of their encoded surface antigen when compared to the vaccine strain. Future research will establish whether this substitution may predispose to a vaccine escape mutant at residue 141, that now has been reported to occur in conjunction with the 140 substitution.

Contrasting roles of rivers and wells as sources of drinking water on attack and fatality rates in a hepatitis E epidemic in Somalia

In early 1988, an increased incidence of acute hepatitis was observed in villages along the Shebeli River in the Lower Shebeli region of Somalia. This was followed by a large epidemic that lasted until late 1989. In a survey of 142 villages with a population of 245,312 individuals, 11,413 icteric cases were recorded, of which 346 died, corresponding to an attack rate and a case fatality rate of 4.6% and 3.0%, respectively. The etiologic role of hepatitis E virus (HEV) in this epidemic was proven by demonstrating anti-HEV in 128 of 145 sampled cases as a sign of recent infection with HEV. In three villages, where a special study protocol was implemented, the attack rate was found to increase significantly with age from 5% in the group 1-4 years of age to 13% in the group 5-15 years of age and to 20% for persons older than 15 years of age. Among cases 20-39 years of age, the female-to-male ratio was 1.5:1, which was a significant predominance of females. As in other hepatitis E outbreaks, there was a high fatality rate in pregnant females, estimated to be 13.8%. The epidemic peaked with the rise in the level of the river during rainfall, suggesting that the disease was waterborne. The attack rate was higher (6.0%) in villages supplied with river water, while fewer cases were recorded in those relying on wells or ponds for their water supply, 1.7% and 1.2%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Complete genomes, phylogenetic relatedness, and structural proteins of six strains of the hepatitis B virus, four of which represent two new genotypes

The genomes of six hepatitis B viral (HBV) strains were sequenced from 10 overlapping amplificates obtained by the polymerase chain reaction. Four of the strains, specifying subtypes ayw4 and adw4q-, represented on the basis of divergency within the S gene two new genomic groups identified by us. The other two strains, encoding adrq- and of Pacific origin, belonged to genomic group C. The relation of these genomes to 21 published human, 1 chimpanzee, and 4 rodent hepadnaviral genomes was analyzed by constructing a phylogenetic dendrogram. Thereby, the segregation of human HBV strains into six genomic groups was confirmed. A consistent grouping of the genomes compared was also obtained in dendrograms based on the P and S genes, although the branching order differed from that based on the entire genomes. Each of the two representatives of genomic groups E and F differed by 8.1 to 13.6% and by 12.8 to 15.5% from the genomes of the other groups and by 1.5 and 3.7% from each other. The two Pacific group C strains differed by 2.7% from each other and by 4.1 to 5.4% from other group C genomes, suggesting that they diverged early from the other group C genomes. The F strains formed the most divergent group of HBV genomes, which may be explained by their representing the original strains of the New World. Within the structural gene products, 17 and 34 amino acids unique for human HBV strains were recorded in the sequenced E and F strains, respectively. Most notable is the Ser81 to Ala81 substitution in an immunodominant region of HBcAg, and the four extra cysteine residues in HBsAg at residues 19, 183, 206, and 220, which might be engaged in additional disulphide bridges. Five residues shared by E and F strains were also unique for human HBV strains. Two of these, Leu127 and Ser140 in HBsAg, were the only substitutions that may explain the w4 reactivity shared by these HBV strains. Interestingly, the Ser140 substitution occurs in an immunodominant loop of the a determinant claimed to be important for the protective immune response to HBV vaccination.

Genetic relatedness of hepatitis B viral strains of diverse geographical origin and natural variations in the primary structure of the surface antigen

A 681 nucleotide fragment of the hepatitis B virus (HBV) genome was sequenced that corresponded to the complete gene for hepatitis B surface antigen (HBsAg) in 80 HBsAg- and hepatitis B e antigen (HBeAg)-positive sera of diverse geographical origins. These and 42 previously published HBV sequences within the S gene were used for the construction of a dendrogram. In this comparison, each of the 122 HBsAg genes was found to be related to one or other of the six previously identified genomic groups of HBV, A to F. The HBV strains within each genomic group showed a characteristic geographical distribution. Group A genomes were represented by 23 strains mainly originating in northern Europe and sub-Saharan Africa. The group B and C genomes, represented by 17 and 28 strains respectively, were confined to populations with origins in eastern Asia and the Far East. The group D genomes, represented by 38 strains, were found worldwide, but were the predominant strains in the Mediterranean area, the Near and Middle East, and in south Asia. Group E genomes, represented by nine strains, were indigenous to western sub-Saharan Africa as far south as Angola. There were indications that the F group, made up of six strains, represented the genomic group of HBV among populations with origins in the New World. Thus, HBV has diverged into genomic groups according to the distribution of mankind in the different continents. As well as giving information on the genetic relationship of HBV strains of different geographical origin, this study also provides information on the primary structure of HBsAg in different regions of the world. Such data might prove valuable in explaining the reported failures to obtain protection with current HBV vaccines.

Severe aplastic anemia associated with seronegative community-acquired hepatitis C virus infection

Aplastic anemia (AA) is a rare complication of viral hepatitis affecting mainly children or young adults. Most reported cases have been associated with community-acquired non-A, non-B hepatitis, but hepatitis A and B have also been implicated in a few patients. We report on a 43-year-old woman with severe AA, in association with acute hepatitis C virus (HCV) infection, diagnosed by detection of HCV RNA by the polymerase chain reaction technique. Her AA was successfully treated with anti-thymocyte globulin and cyclosporin A. The hepatitis C progressed to chronic disease but, despite a follow-up time of 2 years, the patient still has no detectable anti-HCV antibodies, as evaluated with a second-generation anti-HCV assay.

Late seroconversion and high chronicity rate of hepatitis C virus infection in patients with hematologic disorders

BACKGROUND

Patients with hematologic disorders requiring repeated blood and platelet transfusions are at high risk for development of post-transfusion non-A, non-B hepatitis.

PATIENTS AND METHODS

Fifty-five patients with hematologic diseases and post-transfusion non-A, non-B hepatitis were studied. Sera were assayed for hepatitis C virus (HCV) antibodies with a second-generation enzyme-linked immunoassay. Sera from 40 patients were examined for the presence of HCV RNA with a nested PCR method.

RESULTS

The clinical picture of acute non-A, non-B hepatitis did not differ from that described in other patient groups: however, progression to chronic hepatitis was very common (95%). Thirty-eight (95%) of 40 patients, whose sera were analysed both serologically and for the presence of HCV RNA had verified HCV infections. In some patients time to seroconversion was prolonged, up to more than 14 months. Seventeen patients with resistant or relapsed acute leukemia were treated with combination chemotherapy during the acute or chronic phase of hepatitis. Suppression of the inflammatory activity as reflected by a decrease of serum aminotransferase levels was recorded during the subsequent pancytopenic period.

CONCLUSIONS

Hepatitis C has a high chronicity rate in patients with hematologic disorders which parallels the situation of hepatitis B in the immunocompromised host. Furthermore, like the situation in hepatitis B, the hosts' immune response to infection seems to be involved in the pathogenesis of liver injury. Time to seroconversion may be prolonged and detection of HCV RNA is therefore important for diagnosis.

Interferon alpha-2b treatment in an HIV-infected patient with hepatitis B virus induced nephrotic syndrome

A 31-year-old male patient with an asymptomatic HIV infection but with a hepatitis B (HBV) related membraneous glomerulonephritis with nephrotic syndrome was given interferon alpha-2b subcutaneously 3 times weekly for 7.5 months. Zidovudine was added at the 10th week due to low CD4+ cell counts. Before the 6th week of treatment the patient reported a reduced need for diuretics to keep his lower limb edemas at a minimum. This response was partially sustained even after the 7.5 months interferon treatment course. The titers of HBV-DNA decreased markedly during the treatment with interferon but rose to pretreatment levels after discontinuation of the interferon treatment. The serum albumin increased but the proteinuria and hematuria were unaffected. Adverse reactions like fever, myalgias and anemia were tolerable and did not require dose reduction of either interferon or zidovudine. This treatment regimen, at least temporarily, improved the situation for the patient and can be worthwhile to try in HIV-infected patients with HBV related nephritis with nephrotic syndrome.

Important role of hepatitis C virus infection as a cause of chronic liver disease in Somalia

In a case-control study, 62 Somali patients with chronic liver disease (CLD) including primary hepatocellular carcinoma (HCC) and the same number of age and sex matched controls were investigated for serological markers of hepatitis C virus (HCV) and hepatitis B virus (HBV) infections. Antibody to HCV (anti-HCV) was detected in 40.3% and 6.5% of cases and controls, respectively. The corresponding prevalences of hepatitis B surface antigen (HBsAg) were 37.1% and 9.7%, respectively. Of the HBsAg-positive cases, 34.6% had antibodies to hepatitis D virus (anti-HD) compared with 14.3% among the HBsAg-positive controls. Anti-HCV was less prevalent in HBsAg-positive cases than among HBsAg-negative patients (p < 0.001), indicating that these agents were independent causes of CLD/HCC. The odds ratios for patients with CLD/HCC associated with the presence of anti-HCV, anti-HD, HBsAg without anti-HD and anti-HCV, were found to be 9.8, 10.4, and 3.3, respectively. When the patients were divided into tumour and non-tumour cases, using the criteria of serum alpha-fetoprotein > 100 ng/ml and/or solid hepatic lesions detected by ultrasonography, they did not differ with regard to frequencies of HBsAg and/or anti-HCV, although they did differ when these markers were taken together (43/49 versus 5/13, respectively). The mean age of the tumour patients with anti-HCV alone was significantly higher than that of tumour patients with HBsAg as the sole marker, 61.7 versus 31.4 years (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Complete nucleotide sequences of six hepatitis B viral genomes encoding the surface antigen subtypes ayw4, adw4q-, and adrq- and their phylogenetic classification

The complete nucleotide sequences of six hepatitis B viral (HBV) genomes were determined by dideoxy chain termination sequencing of ten overlapping nucleotide fragments obtained by the polymerase chain reaction. Four of the genomes belonged to the two genomic groups E and F of HBV which have been previously identified by us on the basis of sequence divergences within the S gene. Genomic group E encodes the HBsAg subtype ayw4, group F adw4q-. The other two genomes were of Pacific origin within group C and encoded adrq-. The relationship of these complete human HBV genomes to 21 that have been previously published, together with one chimpanzee virus and four rodent hepadnaviral genomes, was investigated by constructing a phylogenetic tree utilizing a combination of distance matrix and approximate parsimonious methods. Thereby, the previously demonstrated segregation of human HBV strains into six genomic groups was confirmed. Both of the representatives of the groups E and F were found to differ by 8.1-13.6% and by 12.8-15.5% from the genomes of the other genomic groups and by 1.5 and 3.7% from each other. Since they differed by more than 8% from the genomes in the other groups, the limit originally used to define HBV, genomic groups their status as new genomic groups was confirmed. The two Pacific group C strains were found to differ by 2.7% from each other and by 4.1 to 5.4% from other group C genomes, suggesting that they diverged early from the other group C genomes. According to both the overall similarity and the phylogenetic dendrogram the F strains formed the most divergent cluster of HBV genomes favoring the concept that they represented the original HBV strains of the New World. The next split in the dendrogram segregated the A, D, E and the chimpanzee strains from the Asian B and C strains. Information on the nucleotide sequences and their encoded products of HBV strains of different genomic groups will provide a basis to understand biological variations of the HBV infection in different parts of the world.

Molecular basis of hepatitis B virus serotype variations within the four major subtypes

Amino acid residues 101 to 180 of hepatitis B surface antigen (HBsAg) were predicted by sequencing the corresponding part of the S gene of hepatitis B virus (HBV) DNA in 46 HBsAg-positive sera, which had been subtyped by immunodiffusion with respect to d/y, w/r, w1 to w4 and q. The sequences of the nine different HBV serotypes defined by these specificities were found to be homogeneous proving that they represent consistent variations of HBV at the genomic level. Residue 127 was found to be important as were Pro, Thr and Leu for w1/w2, w3 and w4, respectively. Five residues were found to differ between ayw1 and ayw2. These were at positions 134 (Phe instead of Tyr), 143 (Thr instead of Ser), 159 (Ala instead of Gly), 161 (Tyr instead of Phe) and 168 (Val instead of Ala). However, all these residues were shared by ayw1 and adw2, implying that Arg122 was also important for w1 expression. All genomes expressing r, apart from one ayr strain, had an Ile126, which might explain the pseudo-allelism of w1 to w4 in relation to r, since this substitution might influence the w epitope. There were two regions where adw4q- and adrq- differed from all the q+ subtypes. These were located at residues 158 and 159, and at residues 177 and 178, where both the q- subtypes had amino acid substitutions in adjacent positions. The mapping of the epitopes defining these antigenic specificities will help to link information on the world-wide distribution of HBsAg subtypes to future molecular epidemiology with regard to HBV.

The risk for hepatitis A, B, and C at two institutions for children in Somalia with different socioeconomic conditions

The prevalence of serologic markers for hepatitis A, B, and C was investigated in children from two residential institutions in Somalia. Among 596 individuals at one residence (Shebeli), the prevalences were 96% for antibody to hepatitis A virus (anti-HAV), 75% for total hepatitis B virus (HBV) markers, 16% for hepatitis B surface antigen (HBsAg), and 1.5% for antibody to hepatitis C virus (anti-HCV). Corresponding figures for the 76 individuals at a smaller residence (Societe Organisation Sociale, SOS) were 59%, 20%, 3.9%, and 0%, respectively. At Shebeli, the HBsAg carrier rates in the 1-10-year-old age group was 28% for boys and 16% for girls. These rates were significantly higher than in the older children (16% and 7.4% for boys and girls, respectively). Fifty-eight percent of the HBsAg carriers were positive for hepatitis B e antigen. Total HBV markers were significantly more frequent in girls from Shebeli, when their duration of residence was longer than five years (89% versus 63%). The duration of stay did not influence the prevalences of HBsAg, HAV, or HCV antibodies. A followup study of children initially seronegative for HBV markers was carried out after two years. For children at Shebeli 1-10 years old, the annual seroconversion rates to HBV markers (95% confidence interval) was 60.5% (42.7-77.0%). The corresponding rate for children at SOS was 10.2% (5.2-17.5%). The differences between the two institutions in the prevalence of serologic markers for hepatitis A and B, and in the annual seroconversion rate to HBV markers reflected different rates of horizontal transmission.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the amino acid sequences of nine different serotypes of hepatitis B surface antigen and genomic classification of the corresponding hepatitis B virus strains

The surface (S) genes of 12 hepatitis B viruses (HBVs) encoding nine different serotypes of hepatitis B surface antigen (HBsAg) were amplified by the polymerase chain reaction and sequenced. These represented the eight strains of HBV, P1 to P8, defined at an international workshop on HBsAg subtypes in Paris in 1975, and the adrq- subtype. The S genes from additional HBV strains, one ayw4, one adw4 and one ayw1, of sub-Saharan African origin, were also sequenced. The relationship of these 12 new S gene sequences to those of the 20 published previously was investigated by constructing a phylogenetic tree, which confirmed a previous classification into four groups, designated A to D, based on 18 complete HBV genomes. When relating our sequenced S genes to these genomic groups, ayw1 of African origin and P6 (adw2) were both allocated to group A, the reference P1 (ayw1 of Vietnamese origin) was allocated to group B, P5 (ayr), P8 (adr) and adrq- were all related to group C, and P2 (ayw2) and P3 (ayw3) could both be allocated to group D. Interestingly, the S genes of w4 serotype viruses, i.e. P4 (ayw4) and P7 (adw4q-), differed by 4% or more from both previous groups and from each other, suggesting their classification into two new groups, for which the designations E and F are proposed. Genomes specifying ayw were also found in groups A and B; previously sequenced genomes specifying the ayw subtype have all been confined to group D. There were indications that the epitope for subdeterminants of w resided at amino acid positions 125 to 127. Thus, at positions 125 and 127, ayw1, ayw2 and adw2 had T and P residues, respectively, whereas M and T residues were at the corresponding positions of ayw3. Both ayw4 and adw4 had L at residue 127, and all strains expressing r, apart from P5, had an I instead of a T residue at position 126.

Detection of HBV DNA by PCR in serum from an HBsAg negative blood donor implicated in cases of post-transfusion hepatitis B

An HBsAg negative blood donor, and three of her recipients, who developed HBsAg positive post-transfusion hepatitis B, were all positive for serum HBV DNA by polymerase chain reaction (PCR), and by subtype discriminating PCR were found to harbour HBV specifying ayw. Thus HBV specifying ayw. Thus HBV DNA may be detected and sub-typed by PCR in infectious HBsAg negative individuals.

HBcAg induced T-cell independent anti-HBc production in chronic HBsAg carriers

The capacity of the nucleocapsid protein of HBV to function as a T-cell independent antigen in man was studied. When T-cell depleted B-cell cultures were challenged with E coli-derived HBcAg, anti-HBc production was registered in culture supernatants from the majority of chronic HBsAg carriers in a quiescent stage of disease. In contrast, similarly prepared and stimulated cultures from donors with natural acquired immunity to hepatitis B or HB-susceptible controls were non-responsive. Addition of autologous T-cells effectively restored anti-HBc responsiveness in T-cell depleted B-cell cultures from HB-immune donors, demonstrating the T-cell dependency for anti-HBc induction in natural HBV-infection.

Late seroconversion to hepatitis B in a Somali village indicates the important role of venereal transmission

Hepatitis B virus (HBV) markers were investigated in a cross-sectional study in 1985 on sera from 84% of the 648 inhabitants in a rural Somali village. The prevalence of HBV markers increased with age, from 9.7% in subjects less than 12 years old, to 38% in the age group 12-19 years, and to 68% in adults. HBV markers were more common in boys less than 12 years old, 13%, than in girls of the same age group, 5.8% (P less than 0.05). A rapid increase of HBV markers started at adolescence in both sexes. The female cohort showed their highest seroconversion rate during their second decade of life, while the male cohort seroconverted more rapidly in the third decade. Thus, an initially more rapid seroconversion among boys was reversed when the females reached reproductive age, and no sex difference in marker frequencies was observed in the age group 12-19 years. There was a steady increase of HBV markers during the reproductive years in both sexes. The frequencies of HBsAg, as well as total markers, were significantly higher in adult males than females, 14 vs 5.6%, and 77 vs 62%, respectively. HBV markers were more frequent in wives of HBV positive husbands than in those married to HBV negative husbands. No increased marker prevalence was observed among siblings of HBV positive children, nor among their mothers, which disproved the role of vertical and early horizontal transmission. In 1989 the four-year rate of seroconversion was investigated in villagers who were seronegative in 1985. On testing 158 sera from 319 individuals, the seroconversion rate was significantly lower among those younger than 12 years in 1985 compared to those in the older age group, 5 vs 17%.(ABSTRACT TRUNCATED AT 250 WORDS)

IgG subclasses in circulating immune complexes with hepatitis B e antigen in chronic hepatitis B

IgG subclasses of antibodies to hepatitis B e antigen (anti-HBe) complexed to HBeAg were determined in 126 HBsAg-positive sera. In the assay HBeAg complexes were bound to microtitre plates by monoclonal anti-HBe and indicated by biotinylated monoclonals to each of the four human IgG subclasses. To evaluate the specificity of the complexed IgG, serum dilutions were also tested for HBeAg and for subclasses of anti-HBe IgG. Two groups of sera were investigated: (i) 64 sera from 64 HBsAg carriers; and (ii) 62 sera from 13 HBeAg-positive patients, of whom five seroconverted to anti-HBe. At least four sera were available from each of these patients. Complexed anti-HBe IgG was detected in 22 of 30 HBeAg-positive, and in three of HBeAg-negative carrier sera. There was no significant association between presence of complexed anti-HBe and levels of HBeAg in these sera. Complexes with multiple subclass composition were found in 13 of the 25 sera with complexed anti-HBe. The most common IgG subclasses found complexed to HBeAg were IgG1 (75%) and IgG4 (67%). A significant association (P less than 0.05) was found between the presence of free and complexed anti-HBe IgG1 in the carrier sera, indicating that the IgG1 antibodies, complexed to HBeAg, were specific for HBeAg. In the five patients who seroconverted to anti-HBe, anti-HBe IgG1 was detected in the HBeAg-positive phase before seroconversion. In the eight patients with persistent HBeAg antigenemia, free anti-HBe IgG1 was detected in only two sera from two different patients. In one patient, complexed anti-HBe IgG1/IgG4 was detected in all serum samples drawn during a period of 111 months. In conclusion, complexed anti-HBe might be detected several years before apparent seroconversion to anti-HBe in conventional anti-HBe assays. In contrast 'free' anti-HBe IgG1, when detected in HBeAg-positive sera with our anti-HBe subclass assay, seemed to signal ensuing apparent seroconversion to anti-HBe.

Minor role of hepatitis B virus in the causation of chronic liver disease in Somalia indicated by a case-control study

Chronic liver disease (CLD) is frequent in Somalia. In a case-control study, 116 in-patients with CLD were compared with the same number of age and sex matched controls. Demographic variables, use of drugs, symptoms and signs, serological markers for hepatitis B virus (HBV) and serum alpha-foetoprotein (AFP) were assessed. Hepatitis B surface antigen (HBsAg) was found in 44 cases of which 17 had antibodies to hepatitis D virus (anti-HD) and 7 had hepatitis B e antigen (HBeAg). Twenty-three controls were HBsAg-positive, of whom 3 had anti-HD and one HBeAg. Increased relative risks (95% confidence intervals in parentheses) were 2.5 (1.3-4.5) for HBsAg, 6.5 (1.7-21.5) for anti-HD, and 7.4 (0.9-66.5) for HBeAg. Despite the association between the presence of HBV markers and CLD, 62% of the cases had no markers indicating current HBV infection. This was reflected in the low risk attributable to chronic HBV infection (22.6%), which was lower than that in patients with CLD in other African populations with a high HBsAg carrier rate. The prevalence of HBV markers did not differ between cases with AFP greater than 100 ng/ml and those with AFP less than 100 ng/ml. The former were characterized by male predominance, shorter duration of symptoms, and larger mean liver size, indicative of malignancy. The mean age of HBsAg-positive cases with AFP greater than 100 ng/ml was significantly lower (by 7.7 years) than that of HBsAg-negative cases with AFP greater than 100 ng/ml. Among the CLD patients with AFP less than 100 ng/ml, 48 were HBsAg-negative. These cases differed significantly from the other 68 cases in that more were females (35% against 16%), more originated from an agricultural area (56% against 30%), and more were regular consumers of drugs (48% against 28%). In conclusion, factors as yet undefined play a considerable role in the causation of CLD in Somalia. The possibility of determining the role of hepatitis C virus (HCV) awaits the development of more specific assays for anti-HCV antibodies.

Typing of hepatitis B virus genomes by a simplified polymerase chain reaction

The amplification of hepatitis B virus (HBV) DNA sequences in sera for molecular epidemiology of HBV is an important application of the polymerase chain reaction (PCR) with regard to HBV. To simplify the PCR for this purpose, the optimal concentrations of SDS and detergents for carrying out the proteinase K digestion and the amplification of DNA by Taq polymerase were evaluated. It was found that by using 1% deoxycholic acid as detergent for the proteinase K step and diluting the digest 10 times before carrying out the PCR, the phenol extraction of DNA became superfluous. The sensitivity of this procedure equalled that of PCR after phenol extraction on comparable amounts of serum. Four pairs of oligonucleotide primers were compared for amplification of HBV DNA sequences in 48 sera previously subtyped with respect to hepatitis B surface antigen (HBsAg), and in eight sera with different genotypes of HBV, representing the subtypes of HBsAg P1 to P8, defined at an international meeting [Couroucé-Pauty et al.: "HBs Antigen Subtypes." Basel: Karger, 1976]. Two primer pairs, selected from conserved regions in the X and S genes of HBV, gave a positive PCR with sera harbouring all the eight different strains of HBV, resulting in DNA fragments consistent with the sizes deduced from genome sequence data. Two other primer pairs were selected in order to discriminate genotypes with regard to differences between d/y and w/r strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of class and subclass distribution of antibodies to the hepatitis B core and B e antigens in chronic hepatitis B

The IgG subclasses IgM and IgA1 of antibodies to hepatitis B core antigen (anti-HBc) and hepatitis B e antigen (anti-HBe) were assayed in sera from 82 patients with chronic hepatitis B utilising class/subclass-specific enzyme immunoassays (EIA). The solid-phase was either recombinant hepatitis B core antigen (rHBcAg) or rHBcAg converted to HBeAg by addition of 0.1% SDS with remaining HBcAg antigenicity blocked with monoclonal anti-HBc. Anti-HBc IgG1 was detected in 81 sera at a geometrical mean titre (GMT) of 296,110 x divided by 2.9. Anti-HBc IgG2 was not detected in any of the sera, and anti-HBc IgG3 and IgG4 were detected in 50 and 37 sera, respectively. Anti-HBc IgM and IgA1 were both significantly correlated to the presence of HBV DNA. The predominant antibody to HBeAg was found to be IgG1, being detected in 45 sera with a GMT of 1,035 x divided by 3.3. Anti-HBe IgG2 was not detected in any serum, while anti-HBe IgG3 and IgG4 were found in 8 and 23 sera, respectively. Anti-HBe IgG1, IgG3, and IgG4 were mainly detected in sera positive for anti-HBe in RIA (Abbott). No patient was found positive for anti-HBe IgA1 or IgM. Thus, in contrast to HBcAg, HBeAg does not trigger a persistent IgM and IgA1 response in chronic hepatitis B. The levels of anti-HBe IgG1 and IgG3 were much lower than the levels of anti-HBc IgG1 and IgG3. The presence of anti-HBe IgG4 was significantly correlated to that of anti-HBc IgG4.(ABSTRACT TRUNCATED AT 250 WORDS)