An enzyme-linked immunosorbent assay for an antigen related to non-A, non-B hepatitis and its antibody: partial characterization of the antigen and chimpanzee transmission

Inhibition of human hemopoiesis by non-A, non-B hepatitis virus

All etiologies of acute viral hepatitis are associated with a transient suppression of hemopoiesis and, rarely, with the development of aplastic anemia. Both hepatitis A and hepatitis B viruses directly inhibit the growth and differentiation of human bone marrow progenitor cells in vitro. We now report a similar effect of a non-A, non-B (NANB) hepatitis agent on human bone marrow progenitor cells. Three chimpanzees were inoculated with a putative NANB agent. Coded sera were blindly evaluated for their ability to affect human bone marrow colony formation in vitro. Sera obtained during the acute phase of NANB hepatitis inhibited the in vitro growth of human erythroid (CFU-E, BFU-E) and granulocyte-macrophage (CFU-GM) progenitor cells, compared with sera obtained before inoculation. Sera obtained after remission of both the biochemical and histological hepatitis and sera obtained from a chimpanzee who underwent biochemical but not histological remission did not inhibit the stem cell assays as much as the acute phase sera. These results suggest an approach to identifying the viremic phase of NANB hepatitis. Inhibition of human bone marrow proliferation appears to be a common property of all known hepatitis viruses.

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.

Immune response to purified non-A, non-B hepatitis-related antigen demonstrated by leukocyte migration inhibition in patients recovering from the infection

Eight patients, convalescent from acute hepatitis, all negative for HBsAg, anti-HBc, anti-HA-IgM, anti-CMV and anti-EB, and all positive for non-A, non-B related antigen and/or antibody in at least one sample during the course of disease, were investigated. Their specific cell-mediated immunity was tested using the leukocyte migration inhibition test in presence of a previously described non-A, non-B related antigen. A control group consisted of ten individuals (two normal subjects, six patients recovering from acute hepatitis B and two with autoimmune chronic active hepatitis). Leukocyte migration was inhibited by the antigen in seven of the eight patients. The test was negative in all control subjects. It is thus demonstrated that after recovery, patients with non-A, non-B viral hepatitis develop a cellular immune response specific for purified non-A, non-B related antigen. The association between the described antigen and viral hepatitis non-A, non-B can now be established not only by immunoprecipitation, but also by a cellular test.

[Hepatitis non-A, non-B: epidemiologic, clinical, serologic and morphologic aspects]

Hepatitis non-A, non-B (HNANB) is due to one or more transmissible agents, probably viruses. Epidemiologically, HNANB is transmitted predominantly by transfusion of blood or plasma derivatives, and percutaneous inoculation, but a non-percutaneous transmission by the fecal-oral route is also established. However, despite 10 years of intense world-wide research, the transmissible agent, or agents, have not been identified and there are no serological assays for either an antigen or an antibody that can be used to detect this infection. The clinical diagnosis of HNANB remains, therefore, a diagnosis of exclusion mainly of hepatitis A and B, Epstein-Barr virus, cytomegalovirus and drug-induced liver disease. In contrast to hepatitis A and B, the clinical and biochemical course of HNANB tends to be less severe and the proportion of asymptomatic and anicteric cases is higher, but fulminant hepatitis and fatalities also occur. Typically, there is a fluctuating waxing and waning pattern of the serum aminotransferase activities in HNANB. HNANB has a relative high tendency to progress to a chronic stage. The exact frequency of HNANB-induced liver cirrhosis and convincing evidence for an association with hepatocellular carcinoma cannot be assessed, although the persistence of the infectious agent in chronic HNANB and the existence of a chronic asymptomatic carrier state have been proved. By light microscopy there is a broad morphologic spectrum of acute and chronic viral hepatitis, but no single pathognomonic lesion exists that allows a reliable distinction to be made of HNANB from hepatitis A and B. Electron microscopy of liver biopsy specimens of chimpanzees, experimentally infected with HNANB agents, permits the visualisation of cytoplasmic changes, which appear to be specific for infection with HNANB viruses. In human liver biopsy specimens from patients with HNANB, identical ultrastructural cytoplasmic changes could not consistently be demonstrated. In contrast, intranuclear aggregates of spherical and tubular particles measuring 20-29 nm, first described in experimental HNANB in chimpanzees, have been repeatedly demonstrated in acute and chronic HNANB in man. These nuclear particles have been considered as compelling evidence of human HNANB infection. The specificity has been challenged, however, by the demonstration of identical particles in other viral and non-viral hepatopathies and in liver biopsies of healthy volunteers. By immune electron microscopy, a multiplicity of virus-like particles are described in association with HNANB.(ABSTRACT TRUNCATED AT 400 WORDS)

Absence of detectable hepatitis B virus DNA in sera and liver of chimpanzees with non-A, non-B hepatitis

The risk of hepatitis B infections has been reduced by screening of blood donors for hepatitis B surface antigen (HBsAg). However, recipients remain at significant risk of developing post-transfusion hepatitis. Studies have shown that non-A, non-B hepatitis virus(es) are responsible for the majority of post-transfusion hepatitis infections. In spite of many efforts, these non-A, non-B hepatitis viruses have not yet been identified. Epidemiological studies, however, suggest that non-A, non-B hepatitis shares many features with hepatitis B. Recently, Wands et al [1982] showed, in chimpanzees infected with non-A, non-B hepatitis agents, the presence of antigenemia or viremia by radioimmunoassay with monoclonal antibodies directed toward distinct determinants of HBsAg and by molecular hybridization analysis. They suggested that non-A, non-B hepatitis agents may be related, but distinct variant(s) of hepatitis B virus (HBV). In this study, five chimpanzees were inoculated with three different agents that have been shown to transmit non-A, non-B hepatitis. The following inocula were used (I) a factor VIII preparation kindly provided by D.W. Bradley, (II) acute phase serum from a chimpanzee infected with the F strain kindly provided by A.J. Zuckerman, and (III) a DS-antigen serum previously shown by us to transmit non-A, non-B hepatitis [Duermeyer et al, 1983]. All chimpanzees developed a rise in transaminase levels between 8 and 10 weeks after inoculation. None of the chimpanzees was positive for any markers of HBV infection. No evidence was obtained of infection with hepatitis A, cytomegalovirus, or Epstein-Barr virus. One chimpanzee developed chronic liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

AN6520 Ag: an antigen purified from liver with non-A, non-B hepatitis

An extract prepared from the liver of patient with chronic non-A, non-B (NANB) hepatitis was found to produce a precipitin line in immunodiffusion with a serum from a multiply transfused patient and those from patients convalescent from NANB hepatitis. The antigen was purified by gel filtration and density gradient centrifugation. The antigen had a buoyant density of 1.16-1.20 g/cm3 in cesium chloride, a sedimentation coefficient (S20,w) of 51.5, and a molecular weight of larger than 1.5 X 10(6) daltons. Electron microscopic examination revealed particles 29-34 nm in diameter (average 31.5 nm), which could be agglutinated by the specific antiserum. We developed a reverse passive hemagglutination (R-PHA) and a passive hemagglutination (PHA) technique for detection of the new antigen and antibody, respectively, and applied these to human sera. Antibody to the antigen was detected in 19/28 (67.9%) convalescent sera of NANB hepatitis. This prevalence was significantly higher than those found in convalescent sera of type A hepatitis patients (2/17 = 11.8%), type B hepatitis patients (2/15 = 13.3%), and normal blood donors (9/129 = 7.0%) (p less than 0.01); and the prevalence in hepatitis A and B patients did not differ significantly from that of normal donors. Furthermore, most (66.7%) of the cases of NANB hepatitis endemic in Shimizu City, Japan, showed clear seroconversion with respect to this antibody. These results suggest that the new antigen/antibody system is associated with NANB hepatitis.

Demonstration of a transient rheumatoid factor in the acute phase of hepatitis non A, non B

The evaluation of an enzyme-linked immunosorbent assay (ELISA) test designed to detect antigens of hepatitis non A, non B (HNANB) revealed that a rheumatoid factor (RF)-like reaction was interfering. This RF-like reaction was not detectable by routine screening methods for RF, such as latex agglutination or the Waaler Rose test. Testing of sequential sera of chimpanzees with acute HNANB showed that this RF-like reaction was present in the acute phase of HNANB simultaneously with alanine aminotransferase (ALT) elevations. Characterization of this RF-like reaction revealed the presence of an IgM antibody against human IgG that banded in CsCl at 1.3 g/ml and at 19S in sucrose gradients. Absorption with IgG-coated latex particles and anti-human IgM gave further evidence of an RF. By testing sera of patients with different forms of acute viral hepatitis, it was demonstrated that an RF-like factor was also present in seven sera from 9 patients with acute hepatitis A, in two sera from 11 patients with hepatitis B, and seven sera from 11 patients with acute HNANB. The rise of RF in the acute phase of hepatitis A may be an effect of polyclonal stimulation of IgM producing B lymphocytes. The high prevalence of RF in HNANB remains unclear as no polyclonal stimulation of IgM has been observed.

Non-A, non-B hepatitis in hemophilic patients with inhibitor treated with activated prothrombin complex concentrates: lack of correlation with an antigen possibly related to non-A, non-B hepatitis

A population of 30 severe hemophilia-A patients with antibodies to factor VIII, treated with Autoplex since 1980, experienced a 30% incidence of non-A, non-B (NANB) hepatitis. 8 of the 9 patients affected had clinical signs of hepatitis and 7 had ALT levels in excess of 200 IU/l; the mean incubation time was 13 days. Only 5 of the 26 lots of Autoplex used were possibly transmitting the infective agent. An ELISA test to detect an antigen (DS-Ag) possibly related to NANB hepatitis was used to screen hemophilia-A and B patients. Its incidence was lower in patients treated less than 5 times a year (7.9%) than in patients treated over 15 times a year (25-27%) with locally prepared blood derivatives. Following treatment with Autoplex, the incidence of DS-Ag in inhibitor patients increased significantly (50%). In this last population, DS-Ag was shown to be unrelated to the NANB hepatitis observed. Although no direct evidence could be given, Autoplex was likely to transmit both the agent responsible for short incubation NANB hepatitis and DS-Ag.

Detection of non-A, non-B hepatitis antigen by immunocytochemical staining

Liver tissue obtained from a chimpanzee during the acute phase of an experimental non-A, non-B (NANB) hepatitis virus infection was studied by a sensitive immunocytochemical staining procedure for the presence of NANB viral antigens. Initial investigations were conducted with a model system of hepatitis B virus (HBV) antigens for purposes of comparing two immunocytochemical staining methods. Of these two procedures, an immunoperoxidase procedure, utilizing an avidin-biotinylated enzyme complex, was at least 40-fold more sensitive than a conventional immunoperoxidase technique for the detection of HBV-specific tissue antigens. Utilization of the avidin-biotin-amplified immunoperoxidase staining procedure, in conjunction with four primary convalescent antisera obtained from NANB hepatitis-implicated donors, resulted in the observation of NANB virus-associated antigen in the cytoplasm of hepatocytes from an infected chimpanzee liver. These same human antisera were not reactive with a number of uninfected control cells nor with cells infected with HBV, hepatitis A virus, or cytomegalovirus. Preincubation of one of these convalescent NANB sera, or IgG derived thereof, with an acute-phase serum obtained from a NANB hepatitis virus-infected chimpanzee abolished the antibody reactivity. We conclude from these observations that selected convalescent sera from NANB hepatitis virus-infected patients contain low levels of antibody that specifically react with a cytoplasmic antigen associated with NANB virus-infected hepatocytes.

Characterization of DS-antigen, an antigen related to non-A, non-B hepatitis. I. Physico-chemical properties

An enzyme-linked immunosorbent assay for an antigen (termed DS-Ag) related to non-A, non-B hepatitis has recently been developed in our laboratory. The DS-Ag was derived from a proven infectious serum obtained from a patient with haemophilia and it was also detected in the acute phase serum of an experimentally infected chimpanzee. The DS-Ag has now been shown to have a buoyant density in CsCl of 1.32 g/cm2 and a sedimentation coefficient of 20 S. The mean molecular weight, determined by gel chromatography on 4% agarose columns, was found to be 0.9 x 10(6). The DS-Ag recovered from acute-phase chimpanzee serum has identical characteristics. The DS-Ag is stable for 1 h at 56 degrees C, at pH 3, in high concentration of CsCl or Nal and in 20% ether. Complete inactivation occurred after 1 min at 98 degrees C, at pH 2, in chloroform (1:1 mixture), in 1 ppm chlorine and in formalin (1:4000, 72 h 37 degrees C). Our studies showed that DS-Ag bears no resemblance to particles related to well-documented forms of viral hepatitis types A and B or other known pathogens. The DS-Ag is a complex substance which forms an antigenic entity related to non-A, non-B hepatitis.