Particles associated with Australia antigen in the sera of patients with leukaemia, Down's Syndrome and hepatitis

Electron microscopic and solution X-ray scattering observations on the structure of hepatitis B surface antigen

The structure of the small, spherical hepatitis B surface antigen was studied by negative staining, freeze-fracture and freeze-etching electron microscopy and solution X-ray scattering techniques. The protein appears to be organized at the surface into a small number of morphological subunits which display two- and threefold axes of symmetry. The mean particle size was 18.3 nm by negative staining and 19.6 nm by freeze-fracture electron microscopy. The diameter of the individual subunits was about 7.5 nm with an intersubunit distance of about 10.0 nm. The lipid is distributed more homogeneously. Some heterogeneity of the particle structure is apparent which may be due to a slightly variable lipid-protein composition or incomplete or defective particle formation.

Predicted secondary structure similarity in the absence of primary amino acid sequence homology: hepatitis B virus open reading frames

Proteins that are related evolutionarily may have diverged at the level of primary amino acid sequence while maintaining similar secondary structures. Computer analysis has been used to compare the open reading frames of the hepatitis B virus to those of the woodchuck hepatitis virus at the level of amino acid sequence, and to predict the relative hydrophilic character and the secondary structure of putative polypeptides. Similarity is seen at the levels of relative hydrophilicity and secondary structure, in the absence of sequence homology. These data reinforce the proposal that these open reading frames encode viral proteins. Computer analysis of this type can be more generally used to establish structural similarities between proteins that do not share obvious sequence homology as well as to assess whether an open reading frame is fortuitous or codes for a protein.

A glycopeptide containing 15 amino acid residues derived from hepatitis B surface antigen particles: demonstration of immunogenicity to raise anti-HBs in mice

The major polypeptides composing hepatitis B surface antigen (HBsAg) particles are P-I and P-II. P-II shares the same amino acid sequence as P-I and contains an additional carbohydrate moiety of mol. wt approximately 5000. When a purified preparation of P-II was digested with Nagarse and then with Pronase P, it gave rise to a glycopeptide containing 15 amino acid residues and the carbohydrate moiety of P-II. The N-terminal amino acid sequence of the glycopeptide was determined to be Lys-Pro-Thr-Asp-Gly-Asn-. The polysaccharide moiety contained 5 moles of N-acetylglucosamine and was connected with Asn at the sixth position from the N-terminus. When mice were immunized against this HBsAg glycopeptide, they raised humoral antibodies which bound to each of three preparations of P-I derived from HGsAg particles of subtypes adw, adr and ayw, thereby indicating that the sequence of 15 amino acids in the glycopeptide would constitute a common antigenic structure of HBsAg.

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.

Rapid identification of viruses by a simple indirect immune electron microscopy technique using ferritin-labelled antibodies

A simple indirect immune electron microscopy technique using ferritin-labelled antibodies and negative staining to rapidly visualize and identify human viruses is described. The increased electron density given by the ferritin molecules, which also served as a reliable marker, has greatly facilitated virus detection.

Structural relationships between the surface antigens of ground squirrel hepatitis virus and human hepatitis B virus

Several physical, chemical, and serological properties of surface antigen particles from ground squirrel hepatitis virus (GSHsAg) and human hepatitis B virus (HBsAg) were compared. GSHsAg and HBsAg particles were purified from positive sera by gel chromatography and isopycnic centrifugation. Both antigens consisted mainly of spherical particles with an average diameter of approximately 20 nm and a buoyant density in CsCl of approximately 1.19 g/ml. Their UV absorption spectra indicated the presence of more tryptophane than tyrosine and the absence of detectable nucleic acid. GSHsAg was found to contain two major polypeptides of approximately 23,000 and 27,000 daltons, with electrophoretic migration rates distinctly faster than those of the two major polypeptides of HBsAg particles. After radiolabeling of purified antigen preparations with Bolton-Hunter reagent, the two major polypeptides of GSHsAg showed almost identical tryptic peptide maps. The tryptic peptide map of the major polypeptide from GSHsAg contained 13 of 37 spots also present in the map of the major HBsAg polypeptide, and 13 of 27 spots in the map of the major HBsAg polypeptide were also present in the map of the major GSHsAg polypeptide. This suggests considerable sequence homology between the major surface antigen polypeptides of the two viruses. However, there was only a weak serological cross-reactivity between antigens of the two viruses. Using an anti-HBs-containing serum with a relatively strong cross-reactivity, GSHsAg was found to consist of at least two antigenically different subspecies. The more strongly cross-reacting from had a slightly higher buoyant density than the other antigenic form.

Status and significance of testing for hepatitis B surface antigen and surface antibody

Following Blumberg's discovery of hepatitis B surface antigen (HBsAg), many attempts have been made to develop several in vitro diagnostic techniques for the detection of this antigen and its homologous antibody. The two-dimensional micro-Ouchterlony immunodiffusion has been the first technique used, rapidly replaced by procedures of increasing sensitivity characterized as second-generation and the currently available third-phase tests which include radioimmunoassay (RIA), reverse passive haemagglutination (RPHA), reverse passive latex agglutination (RPLA) and enzyme immunoassay (EIA). Among these, RIA appears to be the most sensitive and specific, whereas EIA, RPHA and RPLA have the advantage of long shelf-life of stable reagents, no need for sophisticated and expensive equipment and no hazard associated with the handling of radioactive isotopes. Moreover, the sensitivity of EIA should increase by objective reading with a colorimeter. The most sensitive method for the detection of surface antibody (anti-HBs) is again RIA, whereas passive haemagglutination (PHA) had the advantage of providing titres. Finally EIA, based on inhibition of a known amount of HBsAg, has at least the same sensitivity as PHA, but has the advantage that reagents are more stable and that it permits screening for both HBsAg and anti-HBs with the same reagents at the same time. The application of these highly sensitive techniques for the detection of HBsAg and anti-HBs has resulted in a consistent reduction in the incidence of post-transfusion hepatitis type B and in a better understanding of the aetiology, epidemiology and natural history of this infection.

Genetic variation among hepatitis B and related viruses

Hepatitis B virus (HBV) of man has several characteristics that distinguish it from viruses of other groups. These include its ultrastructure, viral DNA size and structure, a virion DNA polymerase which repairs a single-stranded region in the viral DNA, liver tropism, character of persistent infection, and association with hepatitis and hepatocellular carcinoma. Recently three other viruses have been found in other animal species that appear to share these characteristics although the viruses are not identical. HBV, Woodchuck hepatitis virus (WHV), ground squirrel hepatitis virus (GSHV), and duck hepatitis virus (DHV) appear to be members of a new virus group that might be designated the Hepadna virus group. Genetic variation among hepatitis B viruses includes the antigenic variation in the surface antigen (HBsAg) which constitutes the known HBsAg subtypes. There is also frequent variation in DNA base sequence among HBVs isolated from different patients.

Trisodium phosphonoformate inhibits woodchuck hepatitis virus associated DNA polymerase

Recently a new virus has been described which infects woodchucks, Marmota monax. This virus, named woodchuck hepatitis virus (WHV) is closely related to human hepatitis virus (HBV). The virions have the same principal antigenic system involving surface and core determinants and a serological relationship has been found. WHV has also a DNA polymerase associated with the core. It has previously been reported that trisodium phosphonoformate (PFA) but not phosphonoacetic acid (PAA) inhibits DNA polymerase associated with HBV. This investigation shows the same type of inhibition pattern by PFA and PAA on WHV DNA polymerase.

A virus in Beechey ground squirrels that is related to hepatitis B virus of humans

A virus given the name ground squirrel hepatitis virus (or GSHV), with many of the unique characteristics of human hepatitis B virus (HBV), has been found in Beechey ground squirrels in northern California. Common features include virus morphology, viral DNA size and structure, a virion DNA polymerase that repairs a single-stranded region in the viral DNA, crossreacting viral antigens, and persistent infection with viral antigen continuously in the blood. Although similar, GSHV and HBV Are not identical. The ground squirrel virion has a slightly greater diameter, the viral surface antigens crossreact only partially and, thus, are not identical, and GSHV DNA has two restriction endonuclease EcoRI cleavage sites in contrast to the single site in HBV DNA. Thus, GSHV is a member of the virus group that includes HBV and the virus recently found in woodchucks in the eastern United States and named woodchuck hepatitis virus. It is not yet known how closely the ground squirrel and woodchuck viruses are related.

Protein kinase activity in hepatitis B virus

Protein kinase activity was found in hepatitis B virions (Dane particles) purified from the plasma of hepatitis B virus-infected patients, in virion cores, and in hepatitis B core antigen particles purified from hepatitis B virus-infected hepatic tissue and was not found in purified hepatitis B surface antigen particle preparations free of Dane particles. Only a fraction of the major polypeptide (apparent size, 19,700 daltons) in Dane particle cores and hepatitis B core antigen particles from infected liver appeared to be phosphorylated, and phosphorylation changed the electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels to that expected for a polypeptide of 20,600 daltons. Five minor polypeptides with apparent sizes between 38,000 and 63,000 daltons were phosphorylated in Dane particles and Dane particle core preparations but were not detected in hepatitis B core antigen particles from infected liver. None of these had electrophoretic mobilities corresponding to those of known hepatitis B surface antigen polypeptides. Prolonged storage of purified hepatitis B core antigen particles or incubation with human immunoglobulin G preparations containing antibody to the hepatitis B core antigen with or without antibody to the hepatitis B e antigen resulted in the conversion of the polypeptide with an apparent size of 20,600 daltons to ones with apparent sizes of 14,700 and approximately 6,000 daltons, suggesting proteolytic cleavage of the 20,600-dalton polypeptide under these conditions.

Hepatitis. A review of the disease and its significance to dentistry

The report is a review of the literature related to hepatitis B and its implications for dental practitioners. Hepatitis B represents a serious health risk among dentists and simple preventive measures can greatly reduce the risk of transmission or contraction of the disease. Certain positive findings in a healthy history should alert the dentist that he may be treating a carrier of hepatitis B. If so, the wearing of gloves, a mask and protective eyewear will almost totally protect one from contracting the disease. To guard against transmission of hepatitis B to other patients in the dental practice, all instruments should be sterilized and all environmental surfaces should be appropriately treated. A person with a confirmed exposure to hepatitis B should be inoculated with immune serum globulin.

Rapid diagnosis of cytomegalovirus infection in infants by electron microscopy

Electron microscopy was applied to the diagnosis of cytomegalovirus infection in infants; we used the pseudoreplica method, which permits detection of herpesvirus particles within 15 to 30 minutes. Viruses were most readily detectable in urines with infectivity titers greater than or equal to 10(4) per milliliter (95 per cent correlation with the tissue-culture method). Virus particles were detected in 18 of 20 urines obtained from symptomatic or asymptomatic, congenitally or postnatally acquired cytomegalovirus infections in infants younger than six months. Viruses were demonstrated in six of 14 infants older than six months, whose urines usually contained greater than 10(4) per milliliter. All five oral specimens examined by electron microscopy were also positive. Viruses were readily detectable in specimens stored or shipped at 4 degrees C for several days, thus permitting physicians anywhere to obtain confirmation of a herpesvirus infection (presumably cytomegalovirus) within one to two days.

Comparison of small hepatitis B surface antigen particles and human serum low density lipoprotein molecules by electron microscopy

The small spherical particles associated with hepatitis B surface antigen (HBsAg) could be distinguished from the low density lipoprotein (LDL) molecules in human serum by examination of coded, negatively stained preparations. The HBsAg associated particles showed a more marked contrast against the background than LDL. Addition of specific antiserum to LDL caused a significantly reduced mean diameter of LDL molecules. An insignificant reduction in size of HBsAg particles was found by corresponding treatment. It is suggested that the antibody molecules protect LDL molecules protect LDL molecules against artificial flattening during preparation.

Hepatitis-B: a review

The recent literature on various aspects of hepatitis-B is reviewed with emphasis on the interrelationships of viral structure, antigenic components, and host immune response in acute, chronic, and asymptomatic carrier states of the infection. The mode of replication and mechanisms of transmission are discussed. Special attention is paid to potential non-parenteral routes of spread. The role of hepatitis-B in associated immune complex diseases and in hepatoma is outlined. A guide to the interpretation of serologic tests for hepatitis-B associated antigen and antibody patterns is presented in relation to the clinical stage and prognosis of the infection. Therapy, except in conceptual terms, is not covered but a summary of the current status of active and passive immunization is given. The unresolved question of the infectivity of carrier medical staff for their patient contacts, and the reverse, is discussed.

Demonstration of subpopulations of Dane particles

Two populations of Dane particles were isolated from the plasma of individuals carrying hepatitis B surface antigen. These populations had densities in CsCl of 1.22 and 1.20 g/ml. Endogenous DNA polymerase activity was found to be associated only with the heavier of these two populations. Using a positive stain, electron microscopic examination of these particles suggested that the heavier the particle contained nucleic acid in its core whereas the lighter particle appeared empty. Cores isolated from Dane particles with densities of 1.22 and 1.20 g/ml banded in CsCl at densities of 1.36 and 1.30 g/ml, respectively. Endogenous DNA polymerase activity was associated only with the higher density core particles.

The localisation of hepatitis B antigen and immunoglobulin G in liver tissue: an immunofluorescence, light and electron microscopic study

Liver tissue specimens for 43 HBAg seropositive patients and 22 HBAg seronegative individuals were investigated for the presence of HBAg with the immunofluorescence technique. Histological diagnoses were established with light microscopy on routinely stained frozen liver sections. The liver specimens of 42 out of the 43 HBAg-positive patients showed positive fluorescence. Three distinct fluorescence patterns could be observed: diffuse, focal and solitary. The diffuse pattern appeared to occur particularly in chronic aggressive or persistent hepatitis, the focal pattern was seen only in the group of patients without obvious alterations and the solitary pattern especially in acute hepatic necrosis.

Viral hepatitis: recent developments and prospects for prevention

During the past decade new development in hepatitis research have shed new light on the etiologic, epidemiologic, immunologic, and prophylactic aspects of type A and B hepatitis virus infection. Recent advances in hepatitis A virus research include: (1) identification of the virus as a 27 nm particle with characteristics resembling an enterovirus, (2) transmission of the infection to marmosets and chimpanzees, and (3) development of specific complement fixation and immune adherence antibody tests. Recent advances in hepatitis B research include: (1) identification of the virus as a 42 nm particle (Dane particle) containing an outer coat, the hepatitis B surface antigen, and an inner core, the hepatitis B core antigen, (2) development of specific tests to detect the hepatitis B antigens and their respective antibodies, (3) transmission of the infection to chimpanzees, (4) development of a specific hepatitis B immune serum globulin, and (5) development of an inactivated hepatitis B vaccine.

Integrator enzyme hypothesis for replication of hepatitis-B virus

A hypothetical model for the replication of hepatitis-B virus is presented. It is suggested that the D.N.A. polymerase associated with Dane particles facilitates integration of viral D.N.A. into the genome of the liver cell. The viral D.N.A. is then replicated with the host genome. The hypothesis accounts for certain curious experimental and clinical observations and makes several predictions which are amenable to laboratory investigation.

Some epidemiological and clinical aspects of hepatitis B antigen and its subtypes

The close association between hepatitis B antigen (HBAg) and the infectious agent of hepatitis B is clear. Many investigations have shown HBAg to be a useful tool for epidemiological studies of hepatitis B. The relation between HBAg and the postulated hepatitis B virus (HBV) is as yet not clear. In light of recent results a possible candidate could be the so-called Dane particle, which has HBAg reactivity on the surface, but possesses an antigenically distinct core. The core has been shown to have associated DNA polymerase activity. The particles which carry HBAg reactivity have surfaces which are antigenically complex. One common specificity a and 2 pairs of mutually exclusive determinants have been recognized namely d and y and w and r but further possible specificities are under investigation. Four different phenotypes have been described, adw, adr, ayw and ayr. Present evidence indicates that adw, adr and ayw are the phenotypic expression of 3 different transmissible strains of HBV. Studies on the epidemiology of these subtypes have shown 3 different geographic patterns. In the USA and Northern Europe both Dw (adw) and YW (ayw) are common, but in the Eastern Mediterranean and Middle East Yw is practically the only type found. In the Far East DR (adr) is the dominating subtype. Investigations have been done to determine whether there are any clinical differences in hepatitis caused by the different tubtypes. No certain differences have been shown.

Can the blood-transmitted hepatitis problem be solved?

Of the approaches presently available for prevention of blood-transmitted hepatitis, most clearly effective is the avoidance of high-risk donor populations, such as most paid commercial donors. It should be emphasized that even after screening for hepatitis B antigen most paid donor blood carries with it a five-ten times higher risk of transmitting hepatitis than volunteer donor blood. Hepatitis B screening is certainly the next most useful approach. However, it has been pointed out that even with the most sensitive of current assays, as much as two-thirds of infective blood may not be eliminated. In part this is due to failure to detect hepatitis B antige, which may be detectable by such currently investigational approaches as selective antibody inhibition or testing for Core antibody. However, a major factor is the inability of hepatitis B screening to eliminate all infectious blood appears to be due to the existence of viruses other than hepatitis B that play a major role in blood-transmitted hepatitis. Tests for detection of carriers of this virus, or viruses, remain to be developed. Improved reporting of hepatitis cases with investigation and registration of implicated donors may provide an additional means for reducing the incidence of hepatitis transmission. The efficiency of additonal approaches, such as transaminase screening of donors and passive or active immunization, remains to be determined.

An evaluation of low voltage counterimmunoelectrophoresis for the detection of hepatitis-B antigen (HB Ag)

A newly available low voltage counterimmunoelectrophoresis (CIEP) system for the detection of HB Ag (Hapindex, Ortho Diagnostics) was compared with a conventional CIEP method used at this laboratory. A total of 1216 sera were tested. The Hapindex system was found to be at least as sensitive as the conventional CIEP. No false positives were found in this series. The elimination of any preparative work makes the Hapindex system particularly suitable for laboratories not testing large numbers of sera for HB Ag. It also eliminates many of the contamination hazards inherent in the conventional method.

Purification of naked intranuclear particles from human liver infected by hepatitis B virus

The isolation and purification of the naked intranuclear particles of a human liver infected with hepatitis B virus is described. The particles had a diameter of 27-28 nm, were hexagonal, and showed the presence of capsomeres and spikes with lengths of 7-10 nm projecting from the surfaces. The particles formed cubic arrays with center-to-center distances of 40-42 nm. The overall particle symmetry was icosahedral. The ultraviolet absorption spectrum of the particles showed a peak at 264 nm with a shoulder at 280 nm. Endogenous DNA polymerase activity was not detected in fractions containing particles. DNA polymerase activity was present when activated DNA or d(A-T)(n) was used as exogenous template.

DNA of a human hepatitis B virus candidate

Particles containing DNA polymerase (Dane particles) were purified from the plasma of chronic carriers of hepatitis B antigen. After a DNA polymerase reaction with purified Dane particle preparations treated with Nonidet P-40 detergent, Dane particle core structures containing radioactive DNA product were isolated by sedimentation in a sucrose density gradient. The radioactive DNA was extracted with sodium dodecyl sulfate and isolated by band sedimentation in a preformed CsCl gradient. Examination of the radioactive DNA band by electron microscopy revealed exclusively circular double-stranded DNA molecules approximately 0.78 mum in length. Identical circular molecules were observed when DNA was isolated by a similar procedure from particles that had not undergone a DNA polymerase reaction. The molecules were completely degraded by DNase 1. When Dane particle core structures were treated with DNase 1 before DNA extraction, only 0.78-mum circular DNA molecules were detected. Without DNase treatment of core structures, linear molecules with lengths between 0.5 and 12 mum, in addition to the 0.78-mum circles were found. These results suggest that the 0.78-mum circular molecules were in a protected position within Dane particle cores and the linear molecules were not within core structures. Length measurements on 225 circular molecules revealed a mean length of 0.78 +/- 0.09 mum which would correspond to a molecular weight of around 1.6 x 10(6). The circular molecules probably serve as primer-template for the DNA polymerase reaction carried out by Dane particle cores. Thermal denaturation and buoyant density measurements on the Dane particle DNA polymerase reaction product revealed a guanosine plus cytosine content of 48 to 49%.

Hepatitis B antigen: antigenic sites related to human serum proteins revealed by affinity chromatography

Hepatitis B antigen-associated particles, isolated from sera of antigen carriers, were submitted to affinity chromatography on columns of insolubilized antibodies to normal human plasma. The particles adsorbed to the immunosorbent at pH 7.2 and were subsequently eluted at pH 2.2. Exposure of the particles to 8 M urea, 5 M KI, pH 2.2, detergents, organic solvents, or proteolytic enzymes failed to prevent their subsequent adsorption to the immunosorbent. This suggests that antigenic determinants related to human plasma proteins are constituent components of hepatitis B antigen-associated particles. These determinants are distinct from the group-specific (a) and subtype-specific (d or y) sites of the hepatitis B antigen and appear to be related to antigenic specificities on prealbumin, albumin, apolipoproteins C and D, and the gamma-chain of immunoglobulin G.

DNA polymerase in the core of the human hepatitis B virus candidate

Experiments were done to show that the human hepatitis B antigen (HBAg)-associated DNA polymerase is a component of Dane particles and their antigenically distinct cores prepared by Nonidet P-40 detergent treatment of Dane particles. Before detergent treatment, the DNA polymerase was precipitated by serum containing anti-HB surface antigen (anti-HB(s)) but not with serum containing anti-HB core antigen (anti-HB(c)). After detergent treatment, the enzyme was precipitated by anti-HB(c)- and not by anti-HB(s)-containing serum. Highly purified 16- to 25-nm HBAg particles blocked only the precipitation of DNA polymerase in untreated HBAg preparations. The 110S structure with which the DNA reaction product remains associated in Nonidet P-40-treated preparations was identified as Dane particle core by immunoprecipitation with serum containing anti-HB(c). The DNA polymerase and the radioactive DNA reaction product were used as markers for core in immunoprecipitation tests for anticore. In such assays, 8 of 11 human sera with anti-HB(s) activity and all of 10 sera from chronic HBAg carriers were found to contain anti-HB(c) activity.