Isolation of an arenavirus from a marmoset with callitrichid hepatitis and its serologic association with disease.

Callitrichid hepatitis (CH) is an acute, often fatal viral infection of New World primates from the family Callitrichidae. The etiologic agent of CH is unknown. We report here the isolation of an arenavirus from a common marmoset (Callithrix jacchus) with CH by using in vitro cultures of marmoset hepatocytes and Vero-E6 cells. Enveloped virions 67 to 133 nm in diameter with ribosomelike internal structures were seen in infected cultures. Immunofluorescence and Western immunoblot analysis using CH-specific antisera (principally from animals exposed to CH during zoo outbreaks) revealed three antigens in cells infected with this CH-associated virus (CHV). These antigens had the same electrophoretic mobilities on sodium dodecyl sulfate-polyacrylamide gels as did the nucleocapsid, GP2, and GPC proteins of lymphocytic choriomeningitis virus (LCMV). Monoclonal antibodies specific for these arenavirus proteins also reacted with the three CHV antigens. Conversely, the CH-specific antisera reacted with the nucleocapsid, GP2, and GPC proteins of LCMV. CHV thus appears to be a close antigenic relative of LCMV. The serologic association of CHV with several CH outbreaks implicate it as the etiologic agent of this disease.     

Persistence of mouse hepatitis virus A59 RNA in a slow virus demyelinating infection in mice as detected by in situ hybridization.

Mouse hepatitis virus strain A59 produces chronic central nervous system demyelination in rodents. As late as 6 months after intracerebral inoculation of mice 4 to 6 weeks old, when infectious virus cannot be recovered and viral antigens cannot be detected in the central nervous systems and livers of these animals, primary demyelination is still evident. Using cloned virus-specific DNAs and the highly sensitive and specific technique of in situ hybridization, we have detected low levels of mouse hepatitis virus A59 RNA in the central nervous systems and livers of mice 10 months after inoculation. We suggest that viral persistence may play a role in mouse hepatitis virus A59-induced chronic demyelination.     

A single antigenomic open reading frame of the hepatitis delta virus encodes the epitope(s) of both hepatitis delta antigen polypeptides p24 delta and p27 delta.

On the basis of the complete nucleotide sequence of the single-stranded, covalently closed circular hepatitis delta virus RNA genome (K.-S. Wang, Q.-L. Choo, A. J. Weiner, J.-H. Ou, R. C. Najarian, R. M. Thayer, G. T. Mullenbach, K. J. Denniston, J. L. Gerin, and M. Houghton, Nature [London] 323:508-514, 1986 [Author's correction, 328:456, 1987]), five long open reading frames (ORFs) encoding polypeptides containing a methionine proximal to the amino terminus were expressed in bacteria. Only polypeptides encoded by the antigenomic ORF5 cross-reacted with antisera obtained from patients with hepatitis delta virus infections. Immunological analysis of viral extracts and the recombinant ORF5 polypeptides synthesized in bacteria and yeast cells revealed that ORF5 encodes the immunogenic epitope(s) shared by both hepatitis delta viral polypeptides p27 delta and p24 delta and probably represents the complete structural gene for p27 delta and p24 delta. We also present evidence that ORF5 encodes the hepatitis delta antigen, an antigen originally found in the nuclei of hepatocytes of infected individuals (M. Rizzetto, M. G. Canese, S. Arico, O. Crivelli, F. Bonino, C. G. Trepo, and G. Verme, Gut 18:997-1003, 1977). A comparison of the primary structure of the predicted hepatitis delta antigen polypeptides with that of the core antigen of the hepatitis B virus shows that these polypeptides are very dissimilar.     

Woodchuck hepatitis virus X protein is required for viral infection in vivo.

The X gene of the mammalian hepadnaviruses is believed to encode a protein of 17 kDa which has been shown to transactivate a wide range of viral and cellular promoters. The necessity for X gene expression during the viral life cycle in vivo has recently been suggested (H.-S. Chen, S. Kaneko, R. Girones, R. W. Anderson, W. E. Hornbuckle, B. C. Tennant, P. J. Cote, J. L. Gerin, R. H. Purcell, and R. H. Miller, J. Virol. 67:1218-1226, 1993). We have independently constructed two variants of woodchuck hepatitis virus (WHV) with mutations in the X coding region. Transient transfection of two different hepatoma cell lines showed that these WHV X gene mutants were competent for virus replication in vitro. To determine whether X expression was required for viral replication in vivo, we injected mutant and wild-type genomes into the livers of susceptible woodchucks. While the wild-type WHV genomes were infectious in all animals examined, the mutant genomes did not initiate a WHV infection in woodchucks. These results indicate that the X gene of the hepadnaviruses plays a major role in viral replication in vivo.     

Core antigen and antibody in woodchucks after infection with woodchuck hepatitis virus

The woodchuck hepatitis virus is a naturally occurring hepatitis B-like virus that infects the eastern woodchuck. Direct immunofluorescence staining for woodchuck hepatitis virus core antigen in liver biopsies demonstrated the presence of this antigen in 14 of 17 chronically infected woodchucks, and in 8 of 10 woodchucks undergoing acute infections. Fluorescent localization of woodchuck hepatitis virus core antigen was typically cytoplasmic, and this was confirmed further by electron microscopy. Experimental infection with woodchuck hepatitis virus was achieved in four of four woodchucks inoculated with serum from chronic carrier woodchucks. All infected animals developed a self-limited disease characterized by seroconversion to antibodies against the major viral antigens (core and surface antigens); naturally acquired acute infection demonstrated a similar course. A chimpanzee seronegative for all markers of hepatitis B virus developed a subclinical infection after inoculation with woodchuck hepatitis virus.     

Natural history of experimental woodchuck hepatitis virus infection: molecular virologic features of the pancreas, kidney, ovary, and testis.

The kinetic patterns of woodchuck hepatitis virus (WHV) infection were monitored in the pancreas, kidneys, ovaries, and testes. Groups of woodchucks experimentally infected with a standardized inoculum of WHV were sacrificed at different times over a 65-week period beginning in the preacute phase of viral infection and continuing to the period of serologic recovery or the establishment of chronic infections and subsequent hepatocellular carcinoma (B. E. Korba, P. J. Cote, F. V. Wells, B. Baldwin, H. Popper, R. H. Purcell, B. C. Tennant, and J. L. Gerin, J. Virol. 63:1360-1370, 1989). Tissues from an additional group of long-term (2 to 3 years) chronic WHV carriers which had been infected with the same WHV inocula were also examined. Viral DNA replication intermediates were found in all four tissues during the acute phase of WHV infection. However, WHV DNA replication intermediates were observed only in the kidneys of a small proportion of the chronically infected animals. Following the acute phase of infection, WHV DNA was present only in the pancreas, kidneys, and ovaries of the chronically infected woodchucks. A progressive evolution of different WHV genomic forms related to the replicative state of WHV was observed in these tissues. Histologic evaluation of these four tissues revealed only minimal, localized lesions which were not correlated with the state of WHV activity. The observations compiled in this study further extend the tissue tropism of WHV.     

An immunosensor with potential for the detection of viral antigens in body fluids, based on surface second harmonic generation

Field methods of assessing the immune status of animals are required to optimise vaccination programmes to control bovine viral diarrhoea (BVD) virus. An optoelectronic immunosensor was evaluated for the detection of viral antigens in a crude cell lysate in a pilot study. Binding of (BVD) virus antigen by two monoclonal antibodies immobilised on two different media (ELISA plate wells, and glass coverslips) was detected and quantified using the laser induced surface second harmonic generation (SSHG) technique. The results for both assays were correlated with an enzyme-linked immunoassay (ELISA) used for the diagnosis of BVD virus infection in cattle (ELISA plate; R(2)=0.86, coverslips; Exp. 1; R(2)=0.75, Exp. 2; R(2)=0.67). The method will allow rapid detection of antigens in the body fluids of farm animals.     

Nonoverlapping antigenic sites of woodchuck hepatitis virus surface antigen and their cross-reactivity with ground squirrel hepatitis virus and hepatitis B virus surface antigens.

Five nonoverlapping antigenic sites (sites I through V) of woodchuck hepatitis virus surface antigen were identified with competitive binding assays involving monoclonal antibodies. Site I contributed to cross-reactions among surface antigens of hepatitis B-like viruses infecting woodchucks, ground squirrels, and humans. At least three distinct sites (sites I, II, and III) are responsible for cross-reactions between woodchuck and ground squirrel hepatitis virus surface antigens. Sites IV and V of woodchuck hepatitis virus surface antigen are not major cross-reactive sites, suggesting that these elicit virus-specific antibodies. There were no cross-reactions with duck hepatitis B virus surface antigen.     

The murine coronavirus mouse hepatitis virus strain A59 from persistently infected murine cells exhibits an extended host range.

In murine 17 Cl 1 cells persistently infected with murine coronavirus mouse hepatitis virus strain A59 (MHV-A59), expression of the virus receptor glycoprotein MHVR was markedly reduced (S. G. Sawicki, J. H. Lu, and K. V. Holmes, J. Virol. 69:5535-5543, 1995). Virus isolated from passage 600 of the persistently infected cells made smaller plaques on 17 Cl 1 cells than did MHV-A59. Unlike the parental MHV-A59, this variant virus also infected the BHK-21 (BHK) line of hamster cells. Virus plaque purified on BHK cells (MHV/BHK) grew more slowly in murine cells than did MHV-A59, and the rate of viral RNA synthesis was lower and the development of the viral nucleocapsid (N) protein was slower than those of MHV-A59. MHV/BHK was 100-fold more resistant to neutralization with the purified soluble recombinant MHV receptor glycoprotein (sMHVR) than was MHV-A59. Pretreatment of 17 Cl 1 cells with anti-MHVR monoclonal antibody CC1 protected the cells from infection with MHV-A59 but only partially protected them from infection with MHV/BHK. Thus, although MHV/BHK could still utilize MHVR as a receptor, its interactions with the receptor were significantly different from those of MHV-A59. To determine whether a hemagglutinin esterase (HE) glycoprotein that could bind the virions to 9-O-acetylated neuraminic acid moieties on the cell surface was expressed by MHV/BHK, an in situ esterase assay was used. No expression of HE activity was detected in 17 Cl 1 cells infected with MHV/BHK, suggesting that this virus, like MHV-A59, bound to cell membranes via its S glycoprotein. MHV/BHK was able to infect cell lines from many mammalian species, including murine (17 Cl 1), hamster (BHK), feline (Fcwf), bovine (MDBK), rat (RIE), monkey (Vero), and human (L132 and HeLa) cell lines. MHV/BHK could not infect dog kidney (MDCK I) or swine testis (ST) cell lines. Thus, in persistently infected murine cell lines that express very low levels of virus receptor MHVR and which also have and may express alternative virus receptors of lesser efficiency, there is a strong selective advantage for virus with altered interactions with receptor (D. S. Chen, M. Asanaka, F. S. Chen, J. E. Shively, and M. M. C. Lai, J. Virol. 71:1688-1691, 1997; D. S. Chen, M. Asanaka, K. Yokomori, F.-I. Wang, S. B. Hwang, H.-P. Li, and M. M. C. Lai, Proc. Natl. Acad. Sci. USA 92:12095-12099, 1995; P. Nedellec, G. S. Dveksler, E. Daniels, C. Turbide, B. Chow, A. A. Basile, K. V. Holmes, and N. Beauchemin, J. Virol. 68:4525-4537, 1994). Possibly, in coronavirus-infected animals, replication of the virus in tissues that express low levels of receptor might also select viruses with altered receptor recognition and extended host range.     

Characterization of replication-competent retroviruses from nonhuman primates with virus-induced T-cell lymphomas and observations regarding the mechanism of oncogenesis.

Rapidly progressive T-cell lymphomas were observed in 3 of 10 rhesus monkeys several months after autologous transplantation of enriched bone marrow stem cells that had been transduced with a retroviral vector preparation containing replication-competent virus (R. E. Donahue, S. W. Kessler, D. Bodice, K. McDonagh, C. Dunbar, S. Goodman, B. Agricola, E. Byrne, M. Raffeld, R. Moen, J. Bacher, K. M. Zsebo, and A. W. Nienhuis, J. Exp. Med. 176:1124-1135, 1992). The animals with lymphoma appeared to be tolerant to retroviral antigens in that their sera lacked antibodies reactive with viral proteins and contained 10(4) to 10(5) infectious virus particles per ml. By molecular cloning and DNA sequencing, we have now demonstrated that the serum from one of the monkeys contained a replication-competent retrovirus that arose by recombination between vector and packaging encoding sequences (vector/helper [V/H] recombinant) in the producer clone used for transduction of bone marrow stem cells. Southern blot analysis demonstrated 14 or 25 copies of this genome per cell where present in two animals. The genome of a second replication-competent virus was also recovered by molecular cloning; it arose by recombination involving the genome of the V/H recombinant and endogenous murine retroviral genomes in the producer clone. Twelve copies of this amphotropic virus/mink cell focus-forming virus genome were present in tumor DNA of one animal, but it was not found in tumor DNA of the other two animals with lymphoma. Southern blot analysis of DNA from various tissues demonstrated common insertion site bands in several samples of tumor DNA from one animal, suggesting clonal origin of the lymphoma. Our data are most consistent with a pathogenic mechanism in which chronic productive retroviral infection allowed insertional mutagenesis of critical growth control genes, leading to cell transformation and clonal tumor evolution.     

Conformational changes in the spike glycoprotein of murine coronavirus are induced at 37 degrees C either by soluble murine CEACAM1 receptors or by pH 8

The spike glycoprotein (S) of the murine coronavirus mouse hepatitis virus (MHV) binds to viral murine CEACAM receptor glycoproteins and causes membrane fusion. On virions, the 180-kDa S glycoprotein of the MHV-A59 strain can be cleaved by trypsin to form the 90-kDa N-terminal receptor-binding subunit (S1) and the 90-kDa membrane-anchored fusion subunit (S2). Incubation of virions with purified, soluble CEACAM1a receptor proteins at 37 degrees C and pH 6.5 neutralizes virus infectivity (B. D. Zelus, D. R. Wessner, R. K. Williams, M. N. Pensiero, F. T. Phibbs, M. deSouza, G. S. Dveksler, and K. V. Holmes, J. Virol. 72:7237-7244, 1998). We used liposome flotation and protease sensitivity assays to investigate the mechanism of receptor-induced, temperature-dependent virus neutralization. After incubation with soluble receptor at 37 degrees C and pH 6.5, virions became hydrophobic and bound to liposomes. Receptor binding induced a profound, apparently irreversible conformational change in S on the viral envelope that allowed S2, but not S1, to be degraded by trypsin at 4 degrees C. Various murine CEACAM proteins triggered conformational changes in S on recombinant MHV strains expressing S glycoproteins of MHV-A59 or MHV-4 (MHV-JHM) with the same specificities as seen for virus neutralization and virus-receptor activities. Increased hydrophobicity of virions and conformational change in S2 of MHV-A59 could also be induced by incubating virions at pH 8 and 37 degrees C, without soluble receptor. Surprisingly, the S protein of recombinant MHV-A59 virions with a mutation, H716D, that precluded cleavage between S1 and S2 could also be triggered to undergo a conformational change at 37 degrees C by soluble receptor at neutral pH or by pH 8 alone. A novel 120-kDa subunit was formed following incubation of the receptor-triggered S(A59)H716D virions with trypsin at 4 degrees C. The data show that unlike class 1 fusion glycoproteins of other enveloped viruses, the murine coronavirus S protein can be triggered to a membrane-binding conformation at 37 degrees C either by soluble receptor at neutral pH or by alkaline pH alone, without requiring previous activation by cleavage between S1 and S2.     

Atomic force microscopy detection of serological markers of viral hepatites B and C

The possibility of detection of serological markers, containing the hepatitis B surface antigen (HBsAg) and hepatitis C virus core-antigen (HCVcoreAg) in human serum, by a new atomic force microscopy (AFM)-based nanotechnological approach has been demonstrated. The antibodies against the hepatitis B virus surface antigen (anti-HBsAg) and the antibodies against the hepatitis C virus core antigen (anti-HCVcoreAg) were immobilized on an AFM-chip. It was shown that such approach enables to detect HBsAg, HCVcoreAg and the viral fragments containing these antigens in the serum. The comparative analysis of detection of HBsAg- and HCVcoreAg-containing particles by the AFM method versus traditional methods (ELISA, PCR) has demonstrated the 75% coincidence of results between the AFM and two other methods.     

A simple, rapid, and sensitive integrated protein microarray for simultaneous detection of multiple antigens and antibodies of five human hepatitis viruses (HBV, HCV, HDV, HEV, and HGV)

Protein microarrays for parallel detection of multiple viral antigens and antibodies have not yet been described in the field of human hepatitis virus infections. Here, we describe a simple, rapid and sensitive integrated protein microarray with three different reaction models. The integrated protein microarray could simultaneously determine in human sera two viral antigens (HBsAg, HBeAg) and seven viral antibodies (HBsAb, HBcAb, HBeAb, HCVAb, HDVAb, HEVAb, HGVAb) of human hepatitis viruses within 20 min. The results of the protein microarray were assessed directly by the naked eye but can also be analyzed by a quantitative detector. The detection limit of this protein microarray was 0.1 ng/ml for HBsAg. Overall, >85% concordance was observed between the integrated protein microarrays and an enzyme-linked immunosorbent assay for above hepatitis viral antigen and antibody detections in human sera. This integrated protein microarray can be easily optimized for clinical use and epidemiological screening for multiple hepatitis virus infections.     

Immune responses in hepatitis C virus infection: the role of dendritic cells

Cellular immune responses are critical for the clearance of hepatitis C virus. Persistent infection results from a narrow and weak cellular immune response, in direct contrast to the broad, strong response associated with viral clearance in acute infection. The presence of dendritic cells in the liver facilitates presentation of viral antigens to both CD4+ and CD8+ T cell populations. Exploiting the potent antigen presentation capability of dendritic cells for immunotherapy of chronic hepatitis C is attractive; however, infection or transfection of segments or the entire hepatitis C virus genome appears to impair the allostimulation capacity of dendritic cells. If dendritic cell immunotherapy for hepatitis C virus infection is to become a reality, the mechanism behind the defective allostimulatory capacity needs to be deciphered.     

Evidence for hepatitis C viral infection in patients with primary hepatocellular carcinoma.

In testing for antibodies to the hepatitis C virus (anti-HCV) in 112 patients with primary hepatocellular carcinoma, 10 of 33 white patients (30%) and 15 of 79 Asian patients (19%) had a positive response to the antibody. The antibody profile to individual hepatitis C viral antigens and the presence of circulating hepatitis C viral RNA were determined in the 25 patients. The anti-HCV antibodies most frequently detected were toward the antigens from the core (C22) and NS3 regions. Serum hepatitis C viral RNA was present in 17 of the 25 patients (68%), and these patients tended to have serum levels of alanine and aspartate aminotransferases higher than those patients without viremia (136 +/- 22 U per liter versus 64 +/- 11 U per liter and 161 +/- 26 U per liter versus 79 +/- 14 U per liter, respectively, both P < .05). Of the 15 Asian patients with hepatocellular carcinoma and anti-HCV, 4 (27%) had coexisting hepatitis B surface antigen (HBsAg) and 13 (87%) had antibodies to either hepatitis B core or surface antigen. Of the 10 white patients with anti-HCV, however, only 1 (10%) had hepatitis B virus antibodies (P < .01). Among 4 Asian patients with coexisting anti-HCV and HBsAg, 1 was found to have serum hepatitis B viral DNA and the other 3 had hepatitis C viral RNA. A history of blood transfusion was obtained from 12 of the 25 patients with anti-HCV (48%); 20 (80%) had coexisting cirrhosis. Our findings support the hypothesis that hepatitis C virus is an important etiologic agent in the development of primary hepatocellular carcinoma in both white and Asian patients in the United States.     

Serological relationship of woodchuck hepatitis virus to human hepatitis B virus.

Two antigenic systems of the woodchuck hepatitis virus have been identified. The relationship between viral antigens of the woodchuck hepatitis virus and the human hepatitis B virus was determined by using immunoprecipitation, hemagglutination, and immune electron microscopy techniques. Antigens found on the cores of the two viruses were cross-reactive. Lack of cross-reactivity between the surface antigens of the two viruses in immunodiffusion experiments suggested that the major antigenic determinants of the viral surfaces are different; however, results of passive hemagglutination tests indicated that there are common minor determinants. Nucleic acid homology, as measured by liquid hybridization, was found to be 3 to 5% of the viral genomes. The results of this study provide further evidence that woodchuck hepatitis virus is the second member of a new class of viruses represented by human hepatitis B virus. Since virus-infected woodchucks may acquire chronic hepatitis and hepatocellular carcinoma, these antigens and their respective antibodies will be useful markers for following the course of virus infection in investigations of the oncogenic potential of this class of viruses. The nucleocapsid antigen described may be a class-specific antigen of these viruses and, thus, may be useful in discovering new members of the group.     

Coronavirus species specificity: murine coronavirus binds to a mouse-specific epitope on its carcinoembryonic antigen-related receptor glycoprotein.

Like most coronaviruses, the coronavirus mouse hepatitis virus (MHV) exhibits strong species specificity, causing natural infection only in mice. MHV-A59 virions use as a receptor a 110- to 120-kDa glycoprotein (MHVR) in the carcinoembryonic antigen (CEA) family of glycoproteins (G. S. Dveksler, M. N. Pensiero, C. B. Cardellichio, R. K. Williams, G. S. Jiang, K. V. Holmes, and C. W. Dieffenbach, J. Virol. 65:6881-6891, 1991; and R. K. Williams, G. S. Jiang, and K. V. Holmes, Proc. Natl. Acad. Sci. USA 88:5533-5536, 1991). The role of virus-receptor interactions in determining the species specificity of MHV-A59 was examined by comparing the binding of virus and antireceptor antibodies to cell lines and intestinal brush border membranes (BBM) from many species. Polyclonal antireceptor antiserum (anti-MHVR) raised by immunization of SJL/J mice with BALB/c BBM recognized MHVR specifically in immunoblots of BALB/c BBM but not in BBM from adult SJL/J mice that are resistant to infection with MHV-A59, indicating a major difference in epitopes between MHVR and its SJL/J homolog which does not bind MHV (7). Anti-MHVR bound to plasma membranes of MHV-susceptible murine cell lines but not to membranes of human, cat, dog, monkey, or hamster cell lines. Cell lines from these species were resistant to MHV-A59 infection, and only the murine cell lines tested were susceptible. Pretreatment of murine fibroblasts with anti-MHVR prevented binding of radiolabeled virions to murine cells and prevented virus infection. Solid-phase virus-binding assays and virus overlay protein blot assays showed that MHV-A59 virions bound to MHVR on intestinal BBM from MHV-susceptible mouse strains but not to proteins on intestinal BBM from humans, cats, dogs, pigs, cows, rabbits, rats, cotton rats, or chickens. In immunoblots of BBM from these species, both polyclonal and monoclonal antireceptor antibodies that block MHV-A59 infection of murine cells recognized only the murine CEA-related glycoprotein and not homologous CEA-related glycoproteins of other species. These results suggest that MHV-A59 binds to a mouse-specific epitope of MHVR, and they support the hypothesis that the species specificity of MHV-A59 infection may be due to the specificity of the virus-receptor interaction.