Morphology of the GB hepatitis agent

Assessment of knowledge and treatment practices of hepatitis B infection in children among health professionals in Krachi districts in Ghana: a cross-sectional study

Background

Hepatitis B virus (HBV) infection remains one of the neglected infectious diseases. Children infected with HBV are at higher risk of becoming chronic carriers. Barriers to measures against HBV in children are attributed to inadequate knowledge by some health professionals. This study assessed knowledge and treatment practices of HBV in children among health professionals.

Materials and Methods

A cross-sectional survey was conducted among health professionals (185) in three districts in Krachi using a structured questionnaire. Stata version 15 was used to analyze participants' responses on awareness, knowledge, and treatment practices. Pearson's product-moment correlation was used to determine the relationship between knowledge and treatment practices. Multivariate regression analysis assessed the relationships between variables at P<0.05 and 95% confidence interval.

Results

20% were not aware of HBV in children and 85% had only fair knowledge about HBV in children. Only 29% indicated good knowledge and treatment practices of HBV in children. A unit increase in knowledge of HBV in children leads to a 1.42 unit increase in awareness (P<0.01), and a 1.3 unit increase in treatment practice (P<0.01) of HBV in children.

Conclusions

Participants demonstrated only fair knowledge about HBV in children. Seminars and workshops on HBV in children for health professionals must intensify.

TT virus (TTV) is not associated with acute sporadic hepatitis

A novel virus, TT virus (TTV), recently discovered by Okamoto et al. in the serum of a patient with posttransfusion hepatitis, is thought to be one of the causative agents of blood-borne acute hepatitis. The association of this virus with acute sporadic hepatitis was evaluated. TTV DNA was detected in 4 (4.9%) of 81 cases of acute hepatitis A, in 5 (16.7%) of 30 cases of acute hepatitis B, in 1 (25.0%) of 4 cases of acute hepatitis C, in 1 (9.1%) of 9 cases of cytomegalovirus and Eppstein-Barr infection, and in 8 (13.6%) of 59 cases of acute hepatitis of unknown etiology. These positive rates of TTV in various etiologies did not differ significantly amongst each other, and were similar to those of healthy volunteers, i.e. 12.0% (12/100). The comparison of levels of alanine aminotransferase, aspartate aminotransferase, total bilirubin, hepaplastin test and prothrombin time between TT virus-positive and -negative patients did not show any differences. This indicates that TTV is neither a main causative agent of acute sporadic hepatitis of unknown etiology, nor does it affect the clinical features of acute hepatitis with already known etiology.

Distinct genotypes of a nonenveloped DNA virus associated with posttransfusion non-A to G hepatitis (TT virus) in plasma and peripheral blood mononuclear cells

TT virus (TTV) is a nonenveloped, single-stranded DNA virus with little sequence homology to known viruses, and associated with elevated transaminase levels in the patients with posttransfusion hepatitis of unknown etiology. The DNA of TTV was detected, by semi-nested polymerase chain reaction, in peripheral blood mononuclear cells (PBMC) from the 30 healthy individuals with circulating virus in plasma. A sequence of 222 bases was determined on 6-10 TTV DNA clones each from plasma and 6 clones -each from PBMC from eight individuals selected at random from this group. TTV can be classified into genotypes separated by an evolutionary distance > 0.30, which can be divided further into subtypes separated by that of 0.15. Three individuals possessed two different TTV variants of distinct genotypes, with predominant genotypes different between plasma and PBMC. Another possessed TTV of the same genotype in both the plasma and PBMC, but clones with a subtype not seen in plasma were observed in PBMC. A third individual had TTV variants with or without a deletion mutation, and those with the deletion mutation abounded only in PBMC. The remaining three individuals were infected with TTV with the same sequence both in plasma and PBMC. These results indicate that TTV variants with phylogenetic differences could infect the same individual, and that some variants would have a predilection for PBMC. It remains to be seen, however, if TTV replicates in PBMC or whether it has been sequestered before its evolution in the host.

A novel DNA virus (TTV) associated with elevated transaminase levels in posttransfusion hepatitis of unknown etiology

By means of representational difference analysis, a viral clone (N22) of 500 nucleotides was isolated from serum of a patient (TT) with posttransfusion hepatitis of unknown etiology. The N22 clone showed a poor homology to any reported sequences. Oligonucleotide primers were deduced from the N22 sequence for detecting it by polymerase chain reaction. N22 sequence in serum banded at a sucrose density of 1.26 g/cm3, indicating its association with a viral particle which was designated TT virus (TTV). Since nucleic acids of TTV were sensitive to DNase I, it would be a DNA virus. TTV DNA was detected in sera from three of the five patients with posttransfusion non-A to G hepatitis, including the index case (TT). TTV DNA titers closely correlated with aminotransferase levels in the three patients. These results indicate that TTV would be a novel DNA virus with a possible capacity to induce posttransfusion non-A to G hepatitis.

ELISA for detection of antibody to the E2 protein of GB virus C

An enzyme linked immunosorbent assay (ELISA) for detection of antibodies to mammalian cell-expressed E2 protein of GB virus C (GBV-C E2) is described. Antibodies to GBV-C E2 are captured on a solid phase coated with affinity purified E2 protein. Bound antibody is detected in an indirect assay format using horseradish peroxidase (HRPO) labeled goat anti-human IgG as the secondary antibody. Following a color development step, absorbance at 492 nm is measured. A population of 100 volunteer blood donors was tested to assess the specificity of this assay. Individuals reactive for antibody to GBV-C E2 can be considered to have been exposed to GB virus C.

GBV-C/HGV: a new human hepatitis-related virus

Two novel potentially hepatotropic flavi-like viruses were recently identified in patients with acute or chronic hepatitis and were provisionally called GBV-C and hepatitis G virus (HGV). The sequence identity analysis of these two viruses clearly indicated that GBV-C and HGV are two isolates of the same virus. In addition, the phylogenic analysis of the aligned viral polyprotein sequences showed that the GBV-C and HGV isolates are closely related to two Flaviviruses (GBV-A and GBV-B) that cause hepatitis in tamarins, and are distantly related to hepatitis C virus (HCV). Taken together, these results demonstrate that GBV-C/HGV belongs to the Flaviviridae family. GBV-C/HGV genomic RNA is detectable in both acute and chronic non-A, nonE hepatitis as well as in a minor proportion of patients with fulminant hepatic failure, hepatocellular carcinoma and in blood donors with or without abnormal alanine aminotransferase. However, the majority of patients with prospectively followed HGV infections have no evidence of liver damage. The high frequency of GBV-C/HGV infections in patients who are coinfected with HBV and/or HCV suggests that these viruses can share a common mode of transmission.

A new hepatitis C virus-like flavivirus in patients with cryptogenic liver disease associated with elevated GGT and alkaline phosphatase serum levels

The intriguing co-infection of two flaviviruses (GBV-A and GBV-B) in tamarins and the recent discovery of another flavivirus (GBV-C/HGV) in humans raises the question of the relations between hepatitis C virus (HCV) and GBV-C/HGV. To address this issue the sera of 285 patients with liver disease (102 patients with cryptogenic and 183 with known forms of chronic liver disease) and 19 patients without liver disease were tested for HGV-RNA. GBV-C/HGV-RNA was detected by RT-PCR using primers encompassing 5'NC and NS5 regions and hybridization with specific biotinilated and radiolabelled probes. GBV-C/HGV RNA was found in 11 of 20 (55%) acute hepatitis C patients, in 13 of 117 (11.1%) patients with chronic hepatitis C, in 11 of 27 patients with a liver transplant (40.7%), one of 19 (5.3%) patients with chronic HBV infection, 15 out of 102 (14.7%) patients with cryptogenic liver disease and two out of 19 patients with inflammatory bowel disease. In cryptogenic patients, elevated serum gammaglutamyl transpeptidase (GGT, higher than twice the normal values) and alkaline phosphatase (ALP, above normal values) levels were significantly associated with GBV-C/HGV-RNA infection (P < 0.001). In conclusion GBV-C/HGV appears to be transmitted in humans by blood exposure and to be associated with liver disease in HCV co-infected patients and in a minority of patients with cryptogenic disease. The virus is only occasionally pathogenic for the liver and when liver damage is present; the association with the combined elevation of GGT and APH serum levels might represent a specific feature of the liver tropism of the agent.

Sequence analysis of hepatitis GB virus C (GBV-C) isolates from 14 patients

In 1995, a new human hepatitis virus belonging to the family Flaviviridae was described and designated hepatitis GBV-C. To investigate variations within the genome of GBV-C and to study the relationship of GBV-C to GBV-A/B or hepatitis C virus (HCV), we established a detection system using reverse transcriptase polymerase chain reaction (RT-PCR) of the putative helicase region (NS3). So far, isolates derived from 14 different GBV-C-positive sera were analyzed (GBV-C/S3-36), showing 80.1-89.4% (mean: 85%) identical nucleotides. The deduced amino acid sequences revealed 97.3% homology. Nucleotide sequences of GBV-C/S3-36 revealed about 60% identity to GBV-A as well as to HCV, but only 56% identity to GBV-B. Amino acid sequences revealed 73.4 and 68.6% similarity to GBV-A and GBV-B, respectively, but a slightly higher percentage of 78.5% to HCV sequences. Thus, according to the putative GBV-C helicase sequence, a subtyping of GBV-C into different genotypes may be necessary.

Hepatitis G virus RNA in the serum of patients with elevated gamma glutamyl transpeptidase and alkaline phosphatase: a specific liver disease? [corrected]

We tested the sera of 67 consecutive patients for hepatitis G virus (HGV) RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). These patients (42 males and 25 females, median age 35 years, range 13-64 years) had liver disease of unknown aetiology and were without markers of hepatitis (A-E) viruses or signs of genetically determined, autoimmune, alcoholic or drug-induced liver disease. The controls in this study were 110 patients (50 females and 60 males, median age 45 years, range 9-65 years) with chronic hepatitis B virus (HBV) infection (19 patients) or hepatitis C virus (HCV) infection (91 patients). Ten of 67 (14.9%) patients with cryptogenic disease were positive for HGV RNA by at least three separate tests; HGV RNA was also detected in one of 19 (5.3%) hepatitis B surface antigen (HBsAg) carriers and in nine of 91 (16.6%) patients with antibody to HCV. These data suggest that HGV occurs as frequently in HCV-infected patients as in those with cryptogenic disease. Elevated serum gamma glutamyl transpeptidase (gamma-GT) (higher than twice the normal value) and alkaline phosphatase levels were found in eight of 10 (80%) HGV RNA positive patients and in six of 57 (10.5%) HGV RNA negative patients (P < 0.0001). Five (50%) HGV RNA positive patients had non-specific inflammatory bile duct lesions. A statistically significant difference was observed between HGV RNA positive and negative patients with chronic HBV or HCV infections (P < 0.029). Therefore, the spectrum of liver disease associated with HGV is wide, but a characteristic lesion of the bile duct leading to elevation of cholestatic enzymes might be specific for this virus.

GB virus C/hepatitis G virus and other putative hepatitis non A-E viruses

The identification of the major agents causing human hepatitis (Hepatitis A, B, C, D and E Viruses) was achieved during the last 30 years. These viruses are responsible for the vast majority of human viral hepatitis cases, but there are still some cases epidemiologically related to infectious agents without any evidence of infection with known virus, designated as hepatitis non A-E. Those cases are considered to be associated with at least three different viruses: 1--Hepatitis B Virus mutants expressing its surface antigen (HBsAg) with altered epitopes or in low quantities; 2--Another virus probably associated with enteral transmitted non A-E hepatitis, called Hepatitis F Virus. Still more studies are necessary to better characterize this agent; 3--Hepatitis G Virus or GB virus C, recently identified throughout the world (including Brazil) as a Flavivirus responsible for about 10% of parenteral transmitted hepatitis non A-E. Probably still other unknown viruses are responsible for human hepatitis cases without evidence of infection by any of these viruses, that could be called as non A-G hepatitis.

Serologic diagnosis of viral hepatitis

Viral hepatitis has become a difficult field in which clinical and laboratory skills are needed to establish the correct diagnosis and plan for the appropriate therapy. For example, it is no longer enough to diagnose chronic hepatitis B or C. Now, the viral titer or viral genotype must be known. The laboratory test then must be understood in the context of the clinical presentation. This article helps the clinician to acquire such working knowledge. It summarizes available data for hepatitis A, B, C, D, and E. It also includes the recently discovered viral agents, hepatitis G and the hepatitis GB agents.

Hepatitis G virus/GB virus C in Brazil. Preliminary report

Hepatitis G virus/GB virus C is a novel flavivirus recently detected in hepatitis non A-E cases. In this study, the presence of this virus in chronic non-B, non-C hepatitis patients was evaluated using GBV-C specific PCR and this virus was detected in one out of thirteen patients. This patient has presented a severe liver failure, has lived for a long time in the Western Amazon basin and no other cause for this clinical picture was reported. The impact of the discovery of this new agent is still under evaluation throughout the world. The study of the prevalence of this virus among chronic hepatitis patients and healthy individuals (as blood donors) will furnish subside to evaluate its real pathogenicity.

The GB hepatitis viruses

The genomes of three new flavi-like viruses, GBV-A, GBV-B and GBV-C have been identified. Nucleic acid molecules corresponding to the genomes of GBV-A and GBV-B were isolated from tamarins with hepatitis which had been infected with the GB agent. RNA sequences corresponding to GBV-C have been shown to be present in sera from humans with non-A-E hepatitis. Sequence comparisons show that these three viruses are more closely related to each other and to hepatitis C virus (HCV) than to any other known viruses. Together with HCV they appear to form a discrete cluster of related viruses within the larger genus of flaviviridae. The pathological significance of these viruses and their association with hepatitis is currently emerging.

Genomic organization of GB viruses A and B: two new members of the Flaviviridae associated with GB agent hepatitis

The genomes of two positive-strand RNA viruses have recently been cloned from the serum of a GB agent-infected tamarin by using representational difference analysis. The two agent, GB viruses A and B (GBV-A and GBV-B, respectively), have genomes of 9,493 and 9,143 nucleotides, respectively, and single large open reading frames that encode potential polyprotein precursors of 2,972 and 2,864 amino acids, respectively. The genomes of these agents are organized much like those of other pestiviruses and flaviviruses, with genes predicted to encode structural and nonstructural proteins located at the 5' and 3' ends, respectively. Amino acid sequence alignments and subsequent phylogenetic analysis of the RNA-dependent RNA polymerases (RdRps) of GBV-A and GBV-B show that they possess conserved sequence motifs associated with supergroup II RNA polymerases of positive-strand RNA viruses. On the basis of similar analyses, the GBV-A- and GBV-B-encoded helicases show significant identity with the supergroup II helicases of positive-strand RNA viruses. Within the supergroup II RNA polymerases and helicases, GBV-A and GBV-B are most closely related to the hepatitis C virus group. Across their entire open reading frames, the GB agents exhibit 27% amino sequence identity to each other, approximately 28% identity to hepatitis C virus type 1, and approximately 20% identity to either bovine viral diarrhea virus or yellow fever virus. The degree of sequence divergence between GBV-A and GBV-B and other Flaviviridae members demonstrates that the GB agents are representatives of two new genera within the Flaviviridae family.

Molecular and serologic analysis in the transmission of the GB hepatitis agents

Two flavivirus-like genomes have recently been cloned from infectious tamarin (Saguinus labiatus) serum, derived from the human viral hepatitis GB strain, which is known to induce hepatitis in tamarins. In order to study the natural history of GB infections, further transmission studies were carried out in tamarins. Reverse-transcription-polymerase chain reaction and enzyme-linked immunosorbant assays were developed for the detection of RNA and antibodies associated with the two agents, GB virus-A and GB virus-B. The infectivity of both of these agents was demonstrated in tamarins to be filterable through a 0.1 micron filter. Two distinct genomes were identified in the serum of eight of the infected tamarins, while in four tamarins, the genomes were detected independently of each other. Although specific antibodies to the GB virus-B epitopes were detected in the serum of animals inoculated with both agents or GB virus-B alone, antibodies to putative epitopes specific to GB virus-A were not detected in any of the animals. All tamarins inoculated with serum containing GB virus-B exhibited an elevation in liver enzyme levels after inoculation. Elevations of serum liver enzyme levels did not occur when GB virus-A was the only agent detected in the serum. Infection with the original infectious tamarin inoculum conferred protection from reinfection with GB virus-B but not with GB virus-A.

Identification of two flavivirus-like genomes in the GB hepatitis agent

A subtractive PCR methodology known as representational difference analysis was used to clone specific nucleotide sequences present in the infectious plasma from a tamarin infected with the GB hepatitis agent. Eleven unique clones were identified, seven of which were examined extensively. All seven clones appeared to be derived from sequences exogenous to the genomes of humans, tamarins, Saccharomyces cerevisiae, and Escherichia coli. In addition, sequences from these clones were not detected in plasma or liver tissue of tamarins prior to their inoculation with the GB agent. These sequences were detected by reverse transcription-PCR in acute-phase plasma of tamarins inoculated with the GB agent. Probes derived from two of the seven clones detected an RNA species of > or = 8.3 kb in the liver of a GB-agent-infected tamarin by Northern blot hybridization. Sequence analysis indicated that five of the seven clones encode polypeptides that possess limited amino acid identity with the nonstructural proteins of hepatitis C virus. Extension of the sequences found in the seven clones revealed that plasma from an infected tamarin contained two RNA molecules > 9 kb long. Limited sequence identity with various isolates of hepatitis C virus and the relative positions of putative RNA helicases and RNA-dependent RNA polymerases in the predicted protein products of these molecules suggested that the GB agent contains two unique flavivirus-like genomes.

Studies of GB hepatitis agent in tamarins

Three tamarins (Saguinus labiatus), two of which had previously been infected with hepatitis A virus and parenteral non-A, non-B hepatitis, were inoculated intravenously with the agent of GB hepatitis. All three animals developed alanine aminotransferase abnormalities 2 weeks after inoculation. Peak alanine aminotransferase levels were recorded 4 weeks postinoculation. These declined thereafter but continued to fluctuate at abnormal levels for 32 weeks. Liver biopsies showed liver cell swelling and inflammation with focal necrosis. Portal tracts and areas around central veins were heavily infiltrated with mononuclear cells. A fourth animal (no previous exposure to hepatitis viruses) inoculated with GB was killed on Day 15 postinoculation. Serum and extracts of liver and feces from this day were used as inocula for three other animals. Only the serum and liver extract transmitted GB hepatitis. The fecal specimen did not transmit and a fecal extract taken at a later date from another animal was also noninfectious. GB hepatitis virus is distinct from the viruses causing Type A and blood-borne non-A, non-B-hepatitis. Although the virus is present in serum and has previously been transmitted per os, it is not shed in feces.

Diagnostic virology using electron microscopic techniques

This chapter illustrates the development of the use of electron microscopy in viral diagnosis. The field covered is confined to medical viral diagnosis, but parallel developments have taken place in both veterinary and botanical fields and techniques derived from both these sources are also included where relevant. It is reported that the scanning transmission mode of operation, which can induce image contrast changes electronically, may enhance studies with unstained sections and perhaps facilitate thin section immune electron microscopy (IEM). The application of negative stain IEM has been particularly useful for the study of the antigenic nature of some of the newly discovered noncultivable viruses. Viral antigens can also be detected in thin sections of infected cells by IEM with suitably labeled specific antibodies. Confirmation of viral infection by electron microscopy on tissues originally processed for light microscopy is also frequently useful.

Non-a, non-b hepatitis: identification of hepatitis-B-like virus particles in serum and liver

Hepatitis B virus-like particles including: small spheres and filaments 15--25 nm in diameter together with a 35--40 nm Dane particle-like virion have been identified in sera of patients with non-A, non-B hepatitis. In a coded serological study, such particles were detected transiently in 3/4 acute, and persistently in 7/8 chronic cases of non-A, non-B hepatitis with non-A, non-B antigenemia. Only 2/12 similar cases without non-A, non-B antigens (Ag) in serum had detectable particles but neither patients with drugs, or type A hepatitis, nor cases of obstructive jaundice. The particles did not express hepatitis B surface (HBs) or non-A, non-B Ag at their surface but were associated, in three patients, with significant endogenous DNA polymerase activity. Furthermore, particles similar to hepatitis B cores (BHc) and also associated with DNA polymerase activity were demonstrated by sucrose gradient ultracentrifugation of a liver homogenate obtained from a patient who had died of non-A, non-B hepatitis. The non-A, non-B hepatitis virion described here appears, therefore, as a hepatitis B-like virus. The exact kinship between these two agents is currently being investigated.

Detection of virus-associated antigen in serum and liver of patients with non-A non-B hepatitis

In a search for serological markers of non-A non-B(NANB) hepatitis, sera from repeatedly transfused and convalescent patients were assayed by immunodiffusion against sera from 12 patients with early acute NANB hepatitis. A new antigen/antibody system distinct from HBsAg was demonstrated in 8 cases. To assess the specificity of the test, serial sera from 17 patients with acute hepatitis of known aetiology (10 due to hepatitis-B virus, 4 to hepatitis-A virus, 3 to drugs) were tested twice a month, together with sera from 14 NANB patients obtained during a prospective post-transfusion study. NANB antigen (Ag) was detected in at least one sample from 12 of the 14 NANB patients (86%) but in none of the other groups. NANB Ag appeared after or just before elevation of transaminase levels and was cleared before they fell to normal. 4 of 5 patients who showed seroconversion to NANB antibody (Ab) had transient hepatitis. In contrast, the alanine adminotransferase value returned to normal in only 1 of the 5 with persistent NANB antigenaemia during 6 months' follow-up. NANB Ag was also demonstrated by immunodiffusion in liver extracts from patients with chronic NANB hepatitis with antigenaemia. Fluorescein-isothiocyanate-labelled gammaglobulins with strong NANB Ab activity revealed specific nuclear fluorescence in foci of hepatocytes on cryostat sectons of these livers but in none of 6 control human livers. The results suggest that the antigen and antibody are specifically linked to NANB hepatitis of long incubation period.

Circulating immune complexes in non-A, non-B hepatitis. Possible masking of viral antigen

Serial serum samples from 22 patients with transfusion-associated non-A, non-B hepatitis and 2 chimpanzees with the experimentally induced disease were tested for circulating immune complexes by Raji-cell radioimmunoassay. 13 patients (59%) and 1 chimpanzee had circulating immune complexes immediately before, coincident with, or during the return to normal of raised aminotransferase activity. 7 of the 10 patients with chronic non-A, non-B hepatitis had detectable complexes at levels which waxed and waned in parallel with changes in serum aminotransferase activity. Immune complexes may contain and mask viral antigens, and their presence may explain the failure of conventional immunological techniques to detect virus antigens.

The epidemiological pattern of hepatitis A, B, and non-A, non-B in Sweden

In a clinical series of 148 patients with acute hepatitis, serological analysis of hepatitis A and hepatitis B markers revealed 16% of the cases as hepatitis type non-A, non-b. Hepatitis A was diagnosed in 27% of the patients with drug addicts as the predominating category, while serological evidence of hepatitis B infection was found in 57%, again with drug addicts in the majority. Drug addicts also predominated among the non-A, non-B cases, and possibly this category of patients is today the main reservoir not only of hepatitis B but also of hepatitis A and non-A, non-B.

Seroepidemiological investigation of patients and family contacts in an epidemic of hepatitis A

Serial blood and faecal samples were collected from patients and family contacts during an outbreak of hepatitis A in a village and tested by a solid-phase competitive type radioimmunoassay for hepatitis A antigen and hepatitis A antibody. The amount and duration of excretion of hepatitis A antigen was correlated with the severity of the illness. In 2 severe clinical cases, hepatitis A antigen was demonstrated in faecal extracts 11 days before the onset of jaundice and continuing for 10 days thereafter, with maximum shedding during the late incubation period. Faecal antigen was demonstrated in low concentrations for only 2 days in a patient with mild disease and in a person with subclinical infection. There was an inverse correlation between the incidence of infection and prevalence of hepatitis A antibody and age. Of 24 infections, 19 (79%) occurred in persons in the age group 0 to 20 years, a group in which only 6% of individuals had pre-existing antibody. Hepatitis A antibody was present in the serum of 3 persons in low titres of 1:20 to 1:40 on the day jaundice developed. The antibody titres increased very rapidly during the following 2 weeks of illness and slowly during the following months, reaching titres of 1:900 to 1:3500. In a separate study, a mean antibody titre of 1:591 was found in 13 patients, 12 years after clinical hepatitis A with jaundice.