Application of a solid-phase radioimmunoassay and immune electron microscopy for hepatitis A in diagnosis and research

Nucleotide sequence of wild-type hepatitis A virus GBM in comparison with two cell culture-adapted variants

In order to study cell tropism and attenuation of hepatitis A virus (HAV), the genome of HAV wild-type GBM and two cell culture-adapted variants, GBM/FRhK and GBM/HFS, were cloned and sequenced after amplification by reverse transcriptase-PCR. During virus cultivation, the HAV variant GBM/FRhK had a strict host range for FRhK-4 cells, in contrast to GBM/HFS, which can be grown in HFS and FRhK-4 cells. The HAV variant GBM/HFS was shown to be attenuated when inoculated into chimpanzees (B. Flehmig, R. F. Mauler, G. Noll, E. Weinmann, and J. P. Gregerson, p. 87-90, in A. Zuckerman, ed., Viral Hepatitis and Liver Disease, 1988). On the basis of this biological background, the comparison of the nucleotide sequences of these three HAV GBM variants should elucidate differences which may be of importance for cell tropism and attenuation. The comparison of the genome between the GBM wild type and HAV wild types HM175 (J. I. Cohen, J. R. Ticehurst, R. H. Purcell, A. Buckler-White, and B. M. Baroudy, J. Virol. 61:50-59, 1987) and HAV-LA (R. Najarian, O. Caput, W. Gee, S. J. Potter, A. Renard, J. Merryweather, G. Van Nest, and D. Dina, Proc. Natl. Acad. Sci. USA 82:2627-2631, 1985) showed a 92 to 96.3% identity, whereas the identity was 99.3 to 99.6% between the GBM variants. Nucleotide differences between the wild-type and the cell culture-adapted variants, which were identical in both cell culture-adapted GBM variants, were localized in the 5' noncoding region; in 2B, 3B, and 3D; and in the 3' noncoding region. Our result concerning the 2B/2C region confirms a mutation at position 3889 (C-->T, alanine to valine), which had been shown to be of importance for cell culture adaptation (S. U. Emerson, C. McRill, B. Rosenblum, S. M. Feinstone, and R. H. Purcell, J. Virol. 65:4882-4886, 1991; S. U. Emerson, Y. K. Huang, C. McRill, M. Lewis, and R. H. Purcell, J. Virol. 66:650-654, 1992), whereas other mutations differ from published HAV sequence data and may be cell specific. Further comparison of the two cell culture-adapted GBM variants showed cell-specific mutations resulting in deletions of six amino acids in the VP1 region and three amino acids in the 3A region of the GBM variant GBM/FRhK.

Comparison of immunological and molecular hybridization detection methods for the detection of hepatitis A virus in sewage

Immune electron microscopy (IEM), radioimmunoassay (RIA) and molecular hybridization with a digoxigenin-labelled cDNA probe were compared for the detection of wild-type human hepatitis A virus (HAV) in raw and treated sewage. In the same experiments, classic tests for culturable enteroviruses were carried out. With the hybridization probes, HAV was detected in three of the 13 affluent samples (23%) and in eight out of 13 effluent samples (61%). For four of the effluent samples, positivity revealed by IEM was confirmed by the cDNA probe. In contrast, two of the samples shown as positive by IEM were negative with the probes. Detection of HAV by RIA was negative in all cases. Demonstration of HAV was higher in effluent than in affluent. No particular relationship was established between demonstration of HAV, on the one hand, and the various concentrations of enteroviruses observed in the same samples on the other. Overall, if all the results, irrespective of the type of water (affluent or effluent), are taken together, 50% of the sewage samples tested were found to contain HAV by one or another method of detection.

Immunopotentiating reconstituted influenza virus virosome vaccine delivery system for immunization against hepatitis A

Hepatitis A virus (HAV) was purified from MRC-5 human diploid cell cultures, inactivated with formalin, and evaluated for safety and immunogenicity in humans. Three vaccine formulations were produced: (a) a fluid preparation containing inactivated HAV, (b) inactivated HAV adsorbed to Al(OH)3, and (c) inactivated HAV coupled to novel immunopotentiating reconstituted influenza virosomes (IRIV). IRIV were prepared by combining phosphatidylcholine, phosphatidylethanolamine, phospholipids originating from the influenza virus envelope, influenza virus hemagglutinin, and neuraminidase. The HAV-IRIV appeared as unilamellar vesicles with a diameter of approximately 150 nm when viewed by transmission electron microscopy. Upon intramuscular injection, the alum-adsorbed vaccine was associated with significantly (P < 0.01) more local adverse reactions than either the fluid or IRIV formulations. 14 d after a single dose of vaccine, all the recipients of the IRIV formulation seroconverted (> or = 20 mIU/ml) versus 30 and 44% for those who received the fluid and alum-adsorbed vaccines, respectively (P < 0.001). The geometric mean anti-HAV antibody titer achieved after immunization with the IRIV-HAV vaccine was also significantly higher (P < 0.005) compared with the other two vaccines.

Myelopoiesis in vitro is suppressed by hepatitis A virus

Perturbations of hematopoietic regulation ranging from transient granulocytopenia to rare cases of bone marrow failure are associated with infections due to hepatitis A virus (HAV). In an attempt to elucidate the pathogenetic mechanisms we had previously established that HAV has a direct suppressive effect on human bone marrow progenitors (CFU-GM, -GEMM, BFU-E). These studies were extended to long-term bone marrow cultures (LTBMC): Inoculation of bone marrow mononuclear cells with HAV did not interfere with the establishment of an adherent stromal layer, nor did the inoculation of already established layers cause any morphologically recognizable changes to the stroma. In contrast, a significant and progressive decline of the CFU-GM content in the culture supernatants was demonstrated. HAV antigen was detected by APAAP stain in a subpopulation of stromal cells, and sequential estimations of virus titers in the supernatants provided evidence for viral replication in primary bone marrow cultures. Interferon-gamma and tumor necrosis factor-alpha levels of infected cultures did not differ from those of uninfected controls. These findings argue for a direct suppression of (pre-) CFU-GM by HAV in a model system (LTBMC) lacking an immune defense which would limit viral replication.

Comparison of ozone inactivation, in flowing water, of hepatitis A virus, poliovirus 1, and indicator organisms

In steadily flowing water at 20 degrees C and pH 7, five organisms had the following order of resistance to ozone (at constant levels of ozone): poliovirus 1 (PV1) less than Escherichia coli less than hepatitis A virus (HAV) less than Legionella pneumophila serogroup 6 less than Bacillus subtilis spores. The tests were repeated at 10 degrees C with HAV, PV1, and E. coli. Ozone inactivation of HAV and E. coli was faster at 10 degrees C than at 20 degrees C. At 20 degrees C, 0.25 to 0.38 mg of O3 per liter was required for complete inactivation of HAV but only 0.13 mg of O3 per liter was required for complete inactivation of PV1.

Immunogenicity of a killed hepatitis A vaccine in seronegative volunteers

32 volunteers who lacked antibody to hepatitis A virus (HAV) received, at intervals of one month, three injections of a killed vaccine made from HAV propagated in diploid human fibroblast cell cultures. In 16 the vaccine was coupled with aluminium hydroxide as adjuvant. The serconversion rates measured by radioimmunoassay, with and without adjuvant respectively, were 13% and 25% at four weeks, 81% and 89% at eight weeks, and 94% and 100% at twelve weeks. Four weeks after the third injection all volunteers had high neutralising antibody titres. Twelve weeks later the titres of anti-HAV and anti-HAV neutralising antibodies had not declined.

Hepatitis A-virus in cell culture. V. Neutralizing antibodies against hepatitis A-virus

A test system for the detection of neutralizing antibodies against hepatitis A-virus (anti-HAV-Nt) is presented. The anti-HAV-Nt assay is performed with Frhk-4/R cells and the hepatitis A virus (HAV) strain GBM/Frhk-4/R which has been adapted to these cells. Non-neutralized HAV is demonstrated 14 days after infection of Frhk-4/R cells using a radio-immunoassay for detecting newly grown HAV. The influence of differing amounts of HAV on the anti-HAV-Nt titre and the effect of variations in incubation time of virus-serum mixtures are described. The time course of anti-HAV-Nt is shown in sera from a hepatitis-A patient which were taken at different stages of the disease. Anti-HAV-Nt is compared with anti-HAV and anti-HAV-IgM. It is shown that anti-HAV-Nt correlates closely with anti-HAV and separated anti-HAV-IgG, but only slightly with anti-HAV-IgM. The test system presented makes possible the demonstration of neutralizing antibodies against HAV in gamma-globulin preparations and during vaccination studies.

Hepatitis A-virus in cell culture. IV. Comparison of cell-culture-produced HAV with stool-derived HAV in diagnostic test systems

Hepatitis A-virus produced in Frhk-4/R cells is used and compared with stool-derived HAV as an antigen in diagnostic test systems. It is shown that the two antigens react identically in the anti-HAV test with anti-HAV-IgG positive human sera. In the anti-HAV-IgM test, too, stool-derived HAV and cell-culture-produced HAV react very similarly. The titres of anti-HAV-IgG and anti-HAV-IgM positive sera, obtained with stool and cell-culture HAV in quantitative antibody determinations, are shown to be identical. It is shown that the problem of HAV antigen production can now be solved by propagation of HAV with Frhk-4/R cells and that this antigen is very useful in diagnostic test systems.

A comparison of enzyme-immunoassay and radioimmunoassay for detection of hepatitis A virus and antibodies against hepatitis A virus

A direct comparison has been made of tracers labelled with an enzyme and with 125I in solid phase enzyme-immunoassay (EIA) and solid phase radioimmunoassay (RIA) for the detection of hepatitis A virus (HAV) antigen and antibodies to HAV. By comparing the binding capacity of peroxidase-labelled anti-HAV-IgG and anti-HAV-F(ab)2 fragments tracers, anti-HAV-IgG was found to have a higher binding capacity than anti-HAV-F(ab)2 fragments in both EIA and RIA. For EIA 16.25-fold more anti-HAV-IgG was needed for one test probe compared to RIA and 32.5-fold more anti-HAV-F(ab)2 fragments. For the detection of HAV antigen from stool preparations and IgG and IgM antibodies against HAV, there were only minor quantitative differences in titre. EIA was as sensitive as RIA.

Use of conventional and IgM-specific radioimmunoassays for anti-hepatitis A antibody in an outbreak of hepatitis A

During a common source outbreak of hepatitis A, we studied the characteristics and utility of commercially available radioimmunoassays for total and IgM-specific antibody to hepatitis A virus. IgM hepatitis A antibody was detectable in all serum specimens obtained up to 119 days following onset from the seven persons with hepatitis A, and as long as 347 days in one person. Acute infection could also be documented by a four-fold or greater increase in titers of hepatitis A antibody, although as long as nine weeks was required between the times acute and convalescent specimens were obtained. The radioimmunoassay for IgM-specific hepatitis A antibody had greater specificity (99 percent versus 84 percent) and a higher positive prediction value (88 percent versus 23 percent) for the diagnosis of acute hepatitis A than did the radioimmunoassy for hepatitis A antibody. Uses of the radioimmunoassay for IgM-specific hepatitis A antibody include rapid diagnosis of acute hepatitis A, differentiation between recent and past hepatitis A infection, and screening for recent hepatitis A infection in epidemiologic investigation.

Hepatitis A virus in cell culture. II. Growth characteristics of hepatitis A virus in Frhk-4/R cells

The propagation of hepatitis A virus (HAV) is shown in a rapidly growing fetal rhesus monkey kidney cell line (Frhk-4/R). In the course of ten passages through Frhk-4/R cells the HAV, which was released in the supernatants of the cell cultures, was adapted to these cells. In the tenth passage 6 days after infection, it was possible to detect low amounts of HAV in the supernatants by radioimmunoassay (RIA). With indirect immunofluorescence 3 days after infection, a specific granular fluorescence was demonstrated in the cytoplasm of cells infected with HAV from the tenth passage. A persistent infection of Frhk-4/R cells appeared with a main peak at a density of 1.32 g/cm(3) in CsCl density gradients. In the 1.32 g/cm(3) fractions, typical HAV particles are shown by electron microscopy. Furthermore the HAV produced in Frhk-4/R cells is shown to be a useful antigen for diagnostic tests.

Hepatitis A virus infection: pathogenesis and serodiagnosis of acute disease

The early development of immune electron microscopic (IEM) methods for the detection of HAV in acute-phase stool suspensions and antibody to HAV (anti-HAV) in serum made it possible to serologically identify cases of hepatitis A using paired acute and convalescent phase sera. Introduction of less cumbersome and time-consuming serologic test methods, including complement fixation (CF) and immune adherence hemagglutination (IAHA), made it feasible to rapidly assay larger numbers of specimens for HAV or anti-HAV. Subsequent development of sensitive immunofluorescence (IF) assays, solid-phase radioimmunoassays (RIA), and enzyme immunoassays (EIA) for HAV and anti-HAV heralded intensive laboratory studies of the biophysical and biochemical properties of the virus as well as efforts to define the pathogenesis and clinical course of disease. Results of the latter studies showed that the bulk of HAV was usually excreted in stool before the onset of clinical symptoms. Other serologic studies demonstrated that all acutely ill patients had circulating anti-HAV IgM, while all convalescent patients were positive for anti-HAV IgG. The development of sensitive serologic tests (RIA and EIA) that could differentiate between anti-HAV IgM and IgG made it possible to serodiagnose an acute case of hepatitis A using a single-phase serum specimen.

Hepatitis A-virus in cell culture: I. propagation of different hepatitis A-virus isolates in a fetal rhesus monkey kidney cell line (Frhk-4)

A fetal rhesus monkey kidney cell line (Frhk-4) was infected with different hepatitis A-virus (HAV) isolates GBG, GBM, GJA. The time-dependent absorption of the HAV isolates of Fhrk-4 cells was measured. Replication of all three isolates in these cells could be demonstrated intracellularly 8--10 weeks after infection, and release of HAV into the supernatant some 10--15 weeks after infection could be shown. The specificity of the virus determination by RIA from supernatants of HAV-infected cells from passages 1, 2, and 3 in Frhk-4 cells was shown with sera that were collected from a chimpanzee infected with MS-1 both before infection as well as during convalescence. These results were subsequently compared with sera collected from human patients before the onset of hepatitis as well as during convalescence. With immunofluorescence microscopy a cytoplasmic fluorescence could be shown in HAV-infected Frhk-4 cells and finally the release of 27 nm HAV particles into the supernatant of HAV-infected Frhk-4 cells could be demonstrated by immune electron microscopy.