[The virus isolated from patient TT (TTV): still an orphan 2 years after its discovery]

TTV is the acronym for a virus isolated two years ago from a patient whose initials were T.T. It is a naked virus probably belonging to the Circoviridae family. TTV has a particle size of 30-50 nm and possesses a single-strand circular DNA. Epidemiologic data are derived from studies looking for the viral DNA by the polymerase chain reaction (PCR). Important differences between early and recent studies appear to be due to the use of PCR assays based on primers located in different regions of the genome. Based on the most recent studies, the prevalence of TTV infections seems very high in the general population. TTV is present in the feces and would be transmitted through the fecal-oral route. It appears to be a ubiquitous virus, also present in various animal species, from chickens to chimpanzees. No association to any pathology has been identified so far, and TTV infection does not have a significant effect on liver disease.

[Hepatitis viruses]

Five different hepatitis viruses that cause acute and chronic hepatitis in human beings have been identified. Hepatitis viruses are designated by the letters A, B, C, D and E and abbreviated as HAV, HBV, HCV, HDV, and HEV, respectively. Although each belongs to a distinctly different virologic group, they share the feature of hepatotropism, which remains poorly understood. HAV and HEV are transmitted through a fecal-oral route. HDV, also referred to as the delta agent, is a defective, parenterally transmitted virus that uses the hepatitis B surface antigen (HBsAg) of HBV as its envelope. Thus, HDV infection occurs only in patient with HBV infection. Application of molecular biologic techniques has been instrumental in elucidating the genomic sequences of the individual hepatitis viruses and in understanding viral gene expression and mechanisms of viral replication. Knowledge of the genomic structure of these viruses and perfection of molecular biological techniques have also led to clinical applicability of molecular diagnostic techniques. Indeed, these molecular diagnostic techniques have rapidly become the standards against which serologic tests are compared.

[Viral hepatitis and morphology of hepatitis viruses]

Our knowledge has increased significantly about the hepatitis viruses and the disease caused by them. The most important hepatitis inducing viruses are the hepatitis A, B, C, D and E viruses, however, probably new members will be added soon. The possibility of differentiation and detection of these viruses was based on methods of molecular biology and serology.

Identification of enterically transmitted hepatitis virus particles by solid phase immune electron microscopy

Small 'featureless' viruses (less than 50 nm) are difficult to identify by routine immune electron microscopy techniques, particularly when they are mixed with debris from stool or cell culture extracts. A combination of conventional immune electron microscopy (IEM) and solid phase IEM (SPIEM) methodologies was used to identify hepatitis A virus (HAV) in stool and cell culture extracts and non-A non-B hepatitis (hepatitis E) in stool extracts. Compared with conventional IEM, the modified SPIEM method resulted in a significant increase in the number of particles observed. Several small aggregates, each containing 2-20 particles, were observed scattered randomly within most grid squares. Similar results were seen with stool extracts from hepatitis E (HEV) infections. The SPIEM method is a simple, highly sensitive specific assay that facilitates rapid identification of enteric hepatitis viruses. Several experiments were done to characterize the effects of altered physical environment within the assay and to evaluate potential modifications.

Virus-like particles in the liver of a patient with fulminant hepatitis and antibody to hepatitis E virus

In earlier studies, hepatitis E virus (HEV) particles were detected in the stools of patients with enterically transmitted non-A, non-B (ENANB) hepatitis, and HEV was etiologically associated with this disease. Such particles have not been observed in the liver, however. We describe the pathological findings in the liver of a young pregnant woman from Nepal who died as a result of fulminant NANB hepatitis. IgM antibody to HEV was detected in the patient's serum by immune electron microscopy, suggesting that she was acutely infected with that virus. On light microscopic examination of the liver we observed cholestatic hepatitis with proliferation of bile ductules and pseudoglandular arrangement of hepatocytes around distended bile canaliculi. Three types of virus-like particles were detected by electron microscopy. The most frequently observed particles were in cells lining small bile ductules; they measured 32-37 nm and were enclosed by a membrane. Particles of a second type were seen in clusters in the sinusoidal cells; they were uniform in size, without a membrane, and measured about 32 nm in diameter. Particles of a third type (65 nm) were found in epithelial cells of the small bile ductules. Among the particles we detected, the 32 nm particles most closely resembled those of HEV.

Epidemic transmission of enterically transmitted non-A, non-B hepatitis in Mexico, 1986-1987

Outbreaks of acute hepatitis occurred in Huitzililla and Telixtac, two rural villages 70 miles south of Mexico City, Mexico, in late 1986. The first outbreak began in Huitzililla in June of that year, 1 month after the start of the rainy season. A census revealed 94 icteric case subjects, for an attack rate of 5%; two women died. Attack rates were higher for persons older than 15 years (10%) than for younger persons. A case-control study showed that illness was highly associated with water-related factors. The second outbreak began in August 1986 in Telixtac. There were 129 case subjects, for an attack rate of 6%; one woman died. Epidemiologic findings were similar to those in Huitzililla, except that most disease transmission was not linked to unsafe water sources. None of 62 case subjects in Huitzililla and only 2 of 53 case subjects in Telixtac tested had serological evidence for recent infection with hepatitis A or B. Two of eight stool samples from Huitzililla and one of the eight stool samples from Telixtac were positive by immune electron microscopy for 32- to 34-nm viruslike particles similar to those seen in cases of enterically transmitted non-A, non-B hepatitis from Asia. To our knowledge, these investigations document for the first time the epidemic transmission of enterically transmitted non-A, non-B hepatitis virus in the Americas.

Expression of infectious viral particles by primary chimpanzee hepatocytes isolated during the acute phase of non-A, non-B hepatitis

Liver wedge biopsies were obtained from chimpanzees during the acute phase of experimental non-A, non-B hepatitis infections. Primary chimpanzee hepatocytes were maintained for over 4 weeks in vitro with a serum-free medium supplemented with growth factors and hormones. The de novo synthesis and secretion of plasma proteins characteristic for differentiated primate hepatocytes were sustained under these culture conditions. Immunocytochemical staining for a non-A, non-B hepatitis-associated antigen revealed expression of this cytoplasmic marker during the culture period, indicating a persistence of the infection in vitro. Tissue culture medium derived from the hepatocyte cultures was used to inoculate a nonimmune chimpanzee. The animal subsequently displayed an increase in the serum levels of alanine aminotransferase, the development of histopathologic alterations indicative of viral hepatitis, and the appearance of liver cell cytoplasmic tubules diagnostic for non-A, non-B hepatitis. Concentrated tissue culture medium examined by electron microscopy contained virus-like particles with an average diameter of 39-46 nm, which exhibited an envelope and inner 37-nm core structure.

Enterically-transmitted non-A, non-B hepatitis

More than 50% of acute viral hepatitis occurring in some developing countries appears to be unrelated to infection by HAV or HBV and accumulating evidence suggests that a high proportion of this non-A, non-B hepatitis (NANB) is enterically transmitted. Epidemics or outbreaks of enterically-transmitted NANB (ET-NANB) have been documented in the Soviet Union, Nepal, Burma, Pakistan, India, Borneo, Somalia, Sudan, Ivory Coast, Algeria, and Mexico. These outbreaks primarily affect young to middle-age adults and are often associated with a high mortality rate in infected pregnant women, approaching 20% in most reported epidemics. Several investigators have reported finding 27 to 34 nm virus-like particles (VLPs) in stools of acutely infected cases. Stools containing these small, non-enveloped VLPs have been shown to cause NANB in experimentally infected cynomolgus macaques, African green monkeys, chimpanzees, rhesus monkeys, and Saguinus mystax monkeys (tamarins). Infected primates have been shown to seroconvert to 27-34 nm VLPs recovered from stools of cases occurring in the Soviet Union, India, Nepal, Burma, Pakistan and/or Mexico, suggesting that ET-NANB is caused by one virus or class of serologically related viruses. The morphological features and physicochemical properties of one candidate virus are very similar to those of some human caliciviruses, a group of viruses that is normally associated with outbreaks of severe diarrhoea.

Animal transmission of enteric non-A, non-B hepatitis infection to Macaca mulatta by faeco-oral route

M. mulatta monkeys were inoculated faeco-orally by enteric non-A, non-B virus to study the development of clinical, biochemical, histopathological and serological changes in the blood and liver. Pooled stool samples positive for putative non-A, non-B viral antigen by micro-ELISA and aggregated viral particles by immune electron microscopy, were administered in two M. mulatta monkeys. Biochemical, histopathological and serological changes were seen in the blood and liver and excretion of 27 nm virus like particles around 27 days of inoculation in the experimental monkey but not in the control animal.

Serial transmission of a putative causative virus of enterically transmitted non-A, non-B hepatitis to Macaca fascicularis and Macaca mulatta

In order to establish an animal model and to identify a causative virus of enterically transmitted non-A, non-B hepatitis, Macaca fascicularis was inoculated with a fecal extract obtained from Myanmar patients with acute sporadic non-A, non-B hepatitis. The primates developed acute hepatitis exhibited by a transient elevation of aminotransferases in the sera and occurrence of hepatic necroinflammation between 2 and 4 weeks postinoculation. Subsequent second passage of the fecal extract made from first-passage primates into another Macaca fascicularis and Macaca mulatta induced acute hepatitis. Likewise, third passage was also successfully performed. Immune electron microscopy of the stool extract incubated with the primate serum at the acute phase of hepatitis showed an aggregation of virus-like particles. These particles consisted of full and empty round particles without an envelope, measuring approximately 27 nm in diameter. A dispersion of similar particles was found ultrastructurally in the hyaloplasm of hepatocytes surrounding the focal necrosis. This putative causative virus appears to be a new hepatitis virus.

Occurrence and character of a putative causative virus of enterically-transmitted non-A, non-B hepatitis in bile

The present investigation confirms the possibility that the etiological agent of enterically-transmitted non-A, non-B (ET-NANB) hepatitis (type E hepatitis), multiplied in hepatocytes, is excreted into the feces via bile. The fecal extract was inoculated into 7 cynomolgus monkeys. Bile juice was collected directly from the gallbladder by needle puncture after abdominal operation 3 to 6 times during the experimental course. All 7 monkeys developed elevated serum aminotransferases, which began gradually approximately 2 weeks postinoculation and reached a peak at 3 to 5 weeks. In parallel with this elevation, both in time and magnitude, necroinflammation was observed in the livers. The virus-like particles (VLPs) were found in the bile juice of all 7 monkeys and the serial occurrence of VLPs was typified as follows: the VLPs were negative on day 7, appeared on day 10 after inoculation, and were present until the 3rd week when the subjects were sacrificed. While the particles were individually dispersed on day 10, they started to exhibit spontaneous aggregation on and after week 2. Also, empty particles were very rare at first, but increased in ratio compared to full ones over time. Thus, the putative causative virus of ET-NANB hepatitis was demonstrated to be excreted through bile. The spontaneous aggregation of VLPs might be due to the specific antibody secreted into the bile juice and was closely correlated with hepatitis activity. The increase in empty particles might indicate an increase in disorganized assembly of the nucleic acid and protein during virus proliferation.

Prevalence of intranuclear particles in liver pathologies

An ultrastructural study of the prevalence of electron dense 23-27 nm intranuclear particles was carried out on liver biopsies from patients with NANB chronic active hepatitis (CAH), Delta + CAH, HBsAg + CAH, nonviral liver pathologies and in one healthy volunteer. The particles were classified according to aggregation pattern and were found to be correlated with NANB CAH and Delta + CAH. No particles were observed in nonviral liver pathologies. A close antigenic relationship has been shown between the cytoplasmic alterations observed in NANB and delta hepatitis in chimpanzees. Our data indicate that there is a structural similarity between the intranuclear particles seen in both Delta and NANB hepatitis, thus reinforcing the hypothesis that the NANB and Delta agents are closely related.

Characterization of the major duck hepatitis B virus core particle protein

The amino acid composition of the major duck hepatitis B virus (DHBV) core particle proteins was determined. The results of this analysis indicated that cores are composed of a single major protein that initiates translation from the second available AUG in the DHBV core gene. Proteins isolated from core particles purified from the cytoplasm of DHBV-infected duck hepatocytes exhibited heterogeneity in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, independent of the stage of viral DNA maturation. Incubation of native cores with alkaline phosphatase removed this heterogeneity, indicating that phosphorylation of external amino acids was responsible. Core protein isolated from mature DHBV purified from serum of infected animals did not display heterogeneity, suggesting a possible role for dephosphorylation in virus maturation.

Viruslike particles in liver in sporadic non-A, non-B fulminant hepatitis

In a patient who followed the typical clinical course of fulminant hepatitis attributable to "sporadic" non-A,non-B (NANB) hepatitis and who finally received treatment by orthotopic liver grafting, three, apparently separate, virus-like agents (26, 45, and 80 nm) and cytoplasmic, reticular tubular structures (CTS) were identified in collapsed and regenerating areas of liver using electron microscopy. The 80-nm particles present within vacuoles, together with the finding of intranuclear rods in association with the smaller particles (26 nm), are similar to those found in the nuclei of cells infected with several different arboviruses. The third type of particle, existing as 45-nm spheres and rods, is similar in morphology only to some form of polyoma virus, which, hitherto, has not been reported as affecting the liver. Unlike typical polyoma virus, replication of the virus "cores" (25-26 nm) was extranuclear and appeared to be occurring in vacuoles. Although analysis for serological markers against a representative panel for arboviruses, flaviviruses, phleboviruses, arenavirus, and nairovirus was negative, an insect vector was implicated in the clinical history.

An enzyme-linked immunoassay for the possible detection of non-A, non-B viral antigen in patients with epidemic viral hepatitis

An enzyme-linked immunosorbent assay has been developed by using IgM antibodies from the acute stage as a source to capture the antigen in stools of patients with epidemic non-A, non-B (NANB) viral hepatitis. 29/69 (42.3%) of the patients and 3/9 (33.3%) contacts were positive for a suspected NANB viral antigen. However, only 1/27 (3.7%) of the negative controls drawn from amongst the patients with amoebiasis, giardiasis, hepatitis due to virus A and healthy individuals was positive for NANB antigen in the stool. The suspected NANB viral antigen was more frequently detected in stools collected between the 14th and 18th day of icteric hepatitis. The study suggests that IgM antibodies from patients with acute viral NANB hepatitis react with an antigen present in the stools of a high proportion of patients with epidemic NANB viral hepatitis. This serological test may be useful to establish the etiological diagnosis of non-A, non-B (fecal-oral) viral hepatitis. ELISA-positive stools contained 27 nm viral particles.

Aetiological agent of enterically transmitted non-A, non-B hepatitis

Virus-like particles (VLPs) with a mean diameter of 32 nm were recovered from the stools of three acute phase cases of enterically transmitted non-A, non-B hepatitis (ET-NANBH) occurring in the Soviet Union, North Africa and North America. VLPs from two of these cases were studied in detail and were shown to react specifically with antibody in acute phase sera obtained from other cases of ET-NANBH in Asia, the Soviet Union, North Africa and North America. Partially purified VLPs were found to sediment at 183S in sucrose gradients and to cross-react with antibody in acute phase sera from geographically isolated cases of ET-NANBH. The latter virus preparations were also used to document the seroconversion of experimentally ET-NANBH-infected cynomolgus macaques to 32 nm VLPs. Our findings indicate that one virus or class of viruses is responsible for the majority of ET-NANBH.

Determining the size of non-A, non-B hepatitis virus by filtration

The approximate size of the H strain of non-A, non-B (NANB) hepatitis virus was determined by filtration through polycarbonate membranes. The accuracy and reproducibility of such filtrations were monitored by filtering selected reference viruses. These studies indicate that strain H, representative of the principal blood-borne NANB hepatitis virus, is 30-60 nm in diameter. It is therefore highly unlikely that NANB hepatitis virus is a retrovirus, as has been suggested.

Enterically transmitted non-A, non-B hepatitis: serial passage of disease in cynomolgus macaques and tamarins and recovery of disease-associated 27- to 34-nm viruslike particles

An experimental model of enterically transmitted non-A, non-B hepatitis (ET-NANBH) was established in tamarins (Saguinus mystax mystax) and cynomolgus macaques (Macaca fascicularis). First-passage animals were inoculated with two different stool suspensions obtained from human patients with well-defined ET-NANBH that originated from Burma and Pakistan, where epidemics of ET-NANBH occur. Both inocula contained 27- ato 34-nm-diameter viruslike particles (VLPs) that were specifically aggregated by acute-phase ET-NANBH sera. ET-NANBH was subpassaged in both tamarins and cynomolgus macaques by using pools of stool suspensions from first-passage animals. One additional passage of disease in cynomolgus macaques resulted in a significantly shortened incubation period and increased severity of disease. VLPs similar to those found in the human inocula were observed in stool specimens of first-, second-, and third-passage cynomolgus macaques and in first- and second-passage tamarins. Our findings indicate that cynomolgus macaques are particularly suitable experimental models for studies of human ET-NANBH. The 27- to 34-nm VLPs found in infected human and primate stools appear to be etiologically linked to disease.

Isolation of a virus from chimpanzee liver cell cultures inoculated with sera containing the agent of non-A, non-B hepatitis

A membrane-coated virus having a diameter of 85-90 nm and containing a 40-45 nm core was found to replicate in cell cultures derived from chimpanzee liver after inoculation of serum containing infective non-A, non-B (NANB) hepatitis viruses from two independent sources. Replication of this agent was not observed when the same cells were inoculated with a chloroform-extracted inoculum or were left uninoculated. Replication involves assembly of virus cores on tubular structures similar to those seen in liver cells of chimpanzees infected with most isolates of NANB virus.

Non-A, non-B epidemic hepatitis: visualization of virus-like particles in the stool by immune electron microscopy

Acute-phase stool samples collected from hepatitis cases during outbreaks of water-borne epidemic hepatitis were examined by immune electron microscopy (IEM). Spherical virus-like particles (27 nm in diameter) were visualized in the stool of a hepatitis patient with serological evidence of non-A, non-B (NANB) hepatitis. The IEM demonstrated serological specificity of the antigen with the patient's own convalescent serum as well as a known pool of NANB hepatitis convalescent sera. It is suggested that these virus-like particles may be the aetiological agent of faeco -orally transmitted NANB epidemic hepatitis in India.

Intracytoplasmic inclusions in human hepatocytes in non-A, non-B hepatitis: an ultrastructural study

An ultrastructural study was carried out on 114 liver biopsies obtained for diagnostic purposes from patients with various pathological disorders of the liver including hepatitis B-related liver disease, non-A, non-B hepatitis, alcoholic liver disease, fatty change, and cryptogenic cirrhosis. The opportunity was taken to evaluate the significance of intracytoplasmic crystalline structures found in the hepatocytes of nine patients with a variety of liver disorders. The cytoplasmic inclusions varied in size up to 2 microns in length and shape and were not limited by membranes. The presence of these inclusions cannot, however, be correlated either specifically with non-A, non-B hepatitis or with other known nonviral liver disease. The functional, physiological, and pathological significance of the crystalline structures remain to be elucidated.

[Non-A, non-B Hepatitis. A progress report]

The present state of the art in non-A, non-B hepatitis is reviewed. Eight years of world-wide efforts in research have not yielded a definite characterization of agent(s) and markers of this viral infection. Diagnosis is therefore established mainly by exclusion of the hepatitis viruses A and B, Epstein-Barr virus and cytomegalovirus, and drug-induced liver disease. Currently available serological, electron microscopic, immune electron microscopic and clinical information on non-A, non-B hepatitis in chimpanzee and man is briefly reviewed. Some light microscopic features provisionally regarded as suggestive of non-A, non-B hepatitis in man are presented. In daily practice the diagnostic tools in the near future will largely depend upon progress in the elaboration of suitable serological test systems and on further confirmation of microscopic findings, unless an unexpected breakthrough occurs through identification and characterization of the virus(es) in non-A, non-B infection.

Ultrastructural alterations in hepatocytes and sinus endothelia in experimental non-A, non-B hepatitis in chimpanzees with and without immunoglobulin prophylaxis

Three chimpanzees were inoculated with an infectious factor VIII preparation. Two of the chimpanzees received in addition a human immunoglobulin preparation as used for prophylaxis in humans. All three chimpanzees developed an acute limited non-A, non-B hepatitis as judged from light and electron microscopic markers after an incubation period of two weeks. The use of immunoglobulin did not prevent the infection. A prolonged incubation of 15 weeks, however, was observed in one animal when alanine aminotransferase (ALT) elevation was used as criterion of infection. In the electron microscope, non-A, non-B hepatitis was characterized by tubular structures, spongelike inclusions and attaching curved membranes, in the absence of nuclear viruslike particles. An additional finding were viruslike particles in crystalline arrays which were found in the cytoplasm of sinusoidal-lining endothelial cells and tubuloreticular complexes.

Non-A, non-B viral hepatitis

Non-A, non-B hepatitis is a newly recognized disease entity. Although initially described as a transfusion related viral infection, the disease can occur in sporadic, endemic, and epidemic settings. There are no confirmed, reproducible serologic tests for associated antigens or antibodies, but electron microscopy has revealed virus-like particles of different sizes. Nonspecific laboratory tests of hepatic dysfunction, especially alanine aminotransferase, are currently utilized to diagnose non-A, non-B hepatitis in patients and may be used to implicate blood donor carriers of this virus. The existence of an infectious non-A, non-B hepatitis agent and proof of a chronic carrier state in humans have been documented by transmission studies in chimpanzees. Cross challenge studies in chimpanzees, as well as some epidemiologic data, suggest that more than one agent causes non-A, non-B hepatitis.

Virus of Pekin ducks with structural and biological relatedness to human hepatitis B virus

A virus found in the sera of Pekin ducks appears to be a new member of the human hepatitis B-like family of viruses. This virus had a diameter of 40 nm and an appearance in the electron microscope similar to that of human hepatitis B virus. The DNA genome of the virus was circular and partially single stranded, and an endogenous DNA polymerase associated with the virus was capable of converting the genome to a double-stranded circle with a size of ca. 3,000 base pairs. An analysis for viral DNA in the organs of infected birds indicated preferential localization in the liver, implicating this organ as the site of virus replication. In all of these aspects, the virus bears a striking resemblance to human hepatitis B virus and appears to be a new member of this family, which also includes ground squirrel hepatitis virus and woodchuck hepatitis virus.

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.

[Non-A non-B hepatitis virus: demonstration of a double antigenic and structural kinship with hepatitis B virus]

Major antigenic identity has been demonstrated by immunodiffusion between the Ag described by Shirachi and confirmed by us (NANB/e) in the serum on non A non B hepatitis and the HBe/3 specificity of hepatitis B virus (HBV). A second Ag (NANB/c) linked to the core of a new virion morphologically similar to HBV and also associated with ADN polymerase activity as recently described, has been identified and purified from an infected liver. This NANB/c Ag also cross reacts with HBc Ag. These results confirm that HBV and the NANB virus defined here belong to the same new class of DNA viruses.

Intranuclear virus-like particles in a case of sporadic non-A, non-B hepatitis

A case of acute hepatitis type non-A, non-B in a 20-year-old woman is reported. Virus-like particles with a size of about 27 nm in diameter could be identified by electron microscopy in numerous hepatocellular nuclei. They are thought to represent one candidate for the intranuclear form of a non-A, non-B hepatitis virus.

Experimental infection of chimpanzees with antihemophilic (factor VIII) materials: recovery of virus-like particles associated with non-A, non-B hepatitis

Non-A, non-B viral hepatitis was transmitted to four colony-born chimpanzees by infusion of three lots of antihemophilic factor (factor VIII) implicated in the transmission of non-A, non-B hepatitis to two human recipients. All four inoculated animals showed histopathological evidence of viral hepatitis, and all demonstrated significant ALT elevations between seven and one-half weeks after inoculation. Acute-phase plasma from one of the infected chimpanzees (no. 771) was shown to induce non-A, non-B hepatitis in two other chimpanzees approximately three weeks after their inoculation. In addition, an acute-phase open liver wedge biopsy obtained from animal no. 771 was processed and examined by immune electron microscopy (IEM) for virus-like particles with convalescent serum from a serologically confirmed case of non-A, non-B hepatitis. Twenty-five to 30 nm (mean = 27 nm) diameter virus-like particles that were either "full" or "empty" were identified in this liver preparation by IEM. Two additional chimpanzees inoculated with a cesium chloride gradient fraction of an isopycnically banded liver homogenate (animal no. 771) also developed elevated ALT activity two to two and one-half weeks later. Our findings have experimentally verified that commercially produced factor VIII materials can induce non-A, non-B hepatitis in champanzees and that the disease can be subpassaged in these animals by inoculation of either acute-phase plasma or liver. These results also provide evidence for the association of 27 nm-diameter virus-like particles with non-A, non-B viral hepatitis.

Biophysical and biochemical properties of CR326 human hepatitis A virus

CR326 human hepatitis A virus purified by isopycnic banding from infected marmoset sera was shown to consist of 27 mmu spherical particles on electron microscopic examination. The particles were identified as hepatitis A virus by tests by infectivity and by specific neutralization of infectivity with convalescent human hepatitis A serum. Also, identical 27 mmu viruses in liver extracts gave specific reactions with hepatitis A antisera when tested by immune electron microscopy. The buoyant density of the virus in CsCl was 1.34 and it was heat (60 C), ether, and acid stable but was destroyed by heat (100 C), formalin (1:4000), and ultraviolet irradiation. Electron microscopic studies of sections of infected marmoset liver showed intracytoplasmic virus particles, usually in vesicles. Presumptive findings for RNA, together with the intracytoplasmic location of the virus, indicated the virus to be of RNA-type. The attributes of the virus indicate it is closely related to the enterovirus family and not to hepatitis B virus.

Incidence and nature of cytoplasmic hepatitis B antigen in hepatocytes

Hepatitis B antigen (HB Ag) in the hepatocytic cytoplasm is detected by immunofluorescence after reaction with fluoresceinated antiserum to HB Ag or by electron microscopy as numerous 20- to 30-nm. tubular and circular structures in dilated cisternae of excess endoplasmic reticulum. On light microscopy, these hepatocytes can be recognized because their cytoplasm has a ground-glass appearance and stains with Gomori's aldehyde fuchsin. Aldehyde fuchsin-positive ground-glass hepatocytes were detected in all 14 asymptomatic carriers of HB Ag and in 16 of 60 HB Ag-seropositive patients with chronic hepatitis, but not in HB Ag-seropositive acute viral hepatitis or in various other HB Ag-seronegative liver diseases. These cells are helpful in identifying on light microscopy HB Ag carriers and a portion of patients with HB Ag-positive chronic hepatitis. Nuclear HB Ag did not stain with aldehyde fuchsin. Nucleic acids were not detected in the ground-glass cytoplasm by special stains at the light or electron microscopic level. We suggest that the tubular and circular structures in the hepatocytic cytoplasm are coat material of the hepatitis B virus or virally coded host cell reaction product rather than the complete hepatitis B virus.