Hepatitis: Emerson SU

Purcell RH, Emerson SU. · Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892-8009, USA. · J Hepatol. · Pubmed #18192058 No free full text.

Abstract: Although hepatitis E was recognized as a new disease in 1980, the virus was first visualized in 1983 and its genome was cloned and characterized in 1991, the disease is probably ancient but not recognized until modern times. Hepatitis E is the most important or the second most important cause of acute clinical hepatitis in adults throughout Asia, the Middle East and Africa. In contrast, hepatitis E is rare in industrialized countries, but antibody (anti-HEV) is found worldwide. HEV is a small round RNA-containing virus that is the only member of the genus Hepevirus in the family Hepeviridae. Although similar to hepatitis A virus in appearance, there are significant differences between the two viruses. Hepatitis E is principally the result of a water-borne infection in developing countries and is thought to be spread zoonotically (principally from swine) in industrialized countries. Because diagnostic tests vary greatly in specificity, sensitivity and availability, hepatitis E is probably underdiagnosed. At present, control depends upon improved hygiene; a highly efficacious vaccine has been developed and tested, but it is not presently available.

Emerson SU, Purcell RH. · Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA. · Pediatr Infect Dis J. · Pubmed #18043454 No free full text.

This publication has no abstract.

Emerson SU, Purcell RH. · National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. · Rev Med Virol. · Pubmed #12740830 No free full text.

Abstract: Hepatitis E virus (HEV) is a positive-stranded RNA virus with a 7.2 kb genome that is capped and polyadenylated. The virus is currently unclassified: the organisation of the genome resembles that of the Caliciviridae but sequence analyses suggest it is more closely related to the Togaviridae. Hepatitis E virus is an enterically transmitted virus that causes both epidemics and sporadic cases of acute hepatitis in many countries of Asia and Africa but only rarely causes disease in more industrialised countries. Initially the virus was believed to have a limited geographical distribution. However, serological studies suggest that HEV may be endemic also in the United States and Europe even though it infrequently causes overt disease in these countries. Many different animal species worldwide recently have been shown to have antibodies to HEV suggesting that hepatitis E may be zoonotic. Although two related strains have been experimentally transmitted between species, direct transmission from an animal to a human has not been documented. There are four currently recognised genotypes and two of the four contain viruses isolated from swine as well as from humans. Regardless of country of origin or genotype of the virus, most, if not all, strains belong to a single serotype. A promising recombinant vaccine candidate comprised of a truncated capsid protein is currently under evaluation in Nepal.

Emerson SU, Purcell RH. · Molecular Hepatitis and Hepatitis Viruses Sections, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. · Trends Mol Med. · Pubmed #11597521 No free full text.

Abstract: Hepatitis E virus causes epidemics of acute hepatitis in many developing countries. It infrequently causes disease in developed countries, but avirulent strains might circulate. Some evidence suggests that hepatitis E might be a zoonosis. There is probably only a single serotype. A candidate vaccine consisting of baculovirus-expressed recombinant capsid protein protected macaques from hepatitis E--it passed phase I clinical trials and is currently scheduled for phase II/III clinical trials.

Bukh J, Forns X, Emerson SU, Purcell RH. · Hepatitis Viruses and Molecular Hepatitis Sections, Laboratory of Infectious Diseases, NIAID, National Institutes of Health, Bethesda, Md 20892-0740, USA. · Intervirology. · Pubmed #11509874 No free full text.

Abstract: Persistent infection with hepatitis C virus (HCV) is an important cause of chronic liver disease worldwide. Therefore, the development of vaccines to prevent HCV infection, or at least to prevent progression to chronicity, is a major goal. Potential HCV vaccine candidates include recombinant proteins, recombinant viruses, DNA constructs, synthetic peptides and virus-like particles. Various vaccine candidates have been shown to generate humoral and cellular immune responses in animals, primarily in mice. However, the efficacy of most vaccine candidates in protecting against HCV has not been tested because the chimpanzee, the only animal other than humans that is susceptible to HCV, is not readily available, requires special facilities, and is very expensive. The course of infection in chimpanzees is similar in its diversity to that in humans and detailed studies in this model are beginning to define the immune responses that can terminate HCV infection. Of relevance for vaccine evaluation was the titration in chimpanzees of different HCV variants to provide well-characterized challenge pools. In addition, monoclonal virus pools generated from chimpanzees infected with cloned viruses make it possible now to examine immunity to HCV without the confounding factor of antigenic diversity of the challenge virus (quasispecies). The vaccine trials performed in chimpanzees to date all have tested the efficacy of immunizations with various forms of the envelope proteins of HCV.

Purcell RH, Emerson SU. · Hepatitis Viruses and Molecular Hepatitis Sections, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. · ILAR J. · Pubmed #11406718 No free full text.

Abstract: Several useful animal models for both hepatitis A and E have been identified, characterized, and refined. At present, all of the best models utilize nonhuman primates: chimpanzees, tamarin species, and owl monkeys for hepatitis A; and macaque species, chimpanzees, and owl monkeys for hepatitis E. Pigs may prove useful for some studies of hepatitis E, and it is hoped that serological evidence of widespread infection of rats with an HEV-like agent may lead to the development of an animal model based on laboratory rats. As has been the case for each of the hepatitis viruses as they have been discovered, the development of useful and reproducible animal model systems has been critical for moving the field forward as expeditiously as possible.

Meunier JC, Russell RS, Engle RE, Faulk KN, Purcell RH, Emerson SU. · Viral Envelopes and Retrovirus Engineering, Human Virology Department, INSERM U758, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France. · J Virol. · Pubmed #18667498 links to  free full text

Abstract: Accumulating evidence suggests that cellular lipoprotein components are involved in hepatitis C virus (HCV) morphogenesis, but the precise contribution of these components remains unclear. We investigated the involvement of apolipoprotein C1 (ApoC1) in HCV infection in the HCV pseudotyped particle system (HCVpp), in the recently developed cell culture infection model (HCVcc), and in authentic HCV isolated from viremic chimpanzees. Viral genomes associated with HCVcc or authentic HCV were efficiently immunoprecipitated by anti-ApoC1, demonstrating that ApoC1 was a normal component of HCV. The infectivities of HCVpp that had been mixed with ApoC1 and, more importantly, untreated HCVcc collected from lysates or media of infected Huh7.5 cells were directly neutralized by anti-ApoC1. Indeed, convalescent anti-HCV immunoglobulin G and anti-ApoC1 each neutralized over 75% of infectious HCVcc particles, indicating that many, if not all, infectious particles were recognized by both antibodies. Moreover, peptides corresponding to the C-terminal region of ApoC1 blocked infectivity of both HCVpp and HCVcc. Altogether, these results suggest that ApoC1 associates intracellularly via its C-terminal region with surface components of virions during viral morphogenesis and may play a major role in the replication cycle of HCV.

Russell RS, Meunier JC, Takikawa S, Faulk K, Engle RE, Bukh J, Purcell RH, Emerson SU. · Hepatitis Viruses and Molecular Hepatitis Sections, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. · Proc Natl Acad Sci U S A. · Pubmed #18334634 links to  free full text

Abstract: The JFH1 strain of hepatitis C virus (HCV) is unique among HCV isolates, in that the wild-type virus can traverse the entire replication cycle in cultured cells. However, without adaptive mutations, only low levels of infectious virus are produced. In the present study, the effects of five mutations that were selected during serial passage in Huh-7.5 cells were studied. Recombinant genomes containing all five mutations produced 3-4 logs more infectious virions than did wild type. Neither a coding mutation in NS5A nor a silent mutation in E2 was adaptive, whereas coding mutations in E2, p7, and NS2 all increased virus production. A single-cycle replication assay in CD81-deficient cells was developed to study more precisely the effect of the adaptive mutations. The E2 mutation had minimal effect on the amount of infectious virus released but probably enhanced entry into cells. In contrast, both the p7 and NS2 mutations independently increased the amount of virus released.

Graff J, Zhou YH, Torian U, Nguyen H, St Claire M, Yu C, Purcell RH, Emerson SU. · Molecular Hepatitis Section, LID, NIAID, National Institutes of Health, Room 6537, Building 50, 50 South Drive, MSC 8009, Bethesda, MD 20892-8009, USA. · J Virol. · Pubmed #18032496 links to  free full text

Abstract: Hepatitis E virus is a nonenveloped RNA virus. However, the single capsid protein resembles a typical glycoprotein in that it contains a signal sequence and potential glycosylation sites that are utilized when recombinant capsid protein is overexpressed in cell culture. In order to determine whether these unexpected observations were biologically relevant or were artifacts of overexpression, we analyzed capsid protein produced during a normal viral replication cycle. In vitro transcripts from an infectious cDNA clone mutated to eliminate potential glycosylation sites were transfected into cultured Huh-7 cells and into the livers of rhesus macaques. The mutations did not detectably affect genome replication or capsid protein synthesis in cell culture. However, none of the mutants infected rhesus macaques. Velocity sedimentation analyses of transfected cell lysates revealed that mutation of the first two glycosylation sites prevented virion assembly, whereas mutation of the third site permitted particle formation and RNA encapsidation, but the particles were not infectious. However, conservative mutations that did not destroy glycosylation motifs also prevented infection. Overall, the data suggested that the mutations were lethal because they perturbed protein structure rather than because they eliminated glycosylation.

Meunier JC, Russell RS, Goossens V, Priem S, Walter H, Depla E, Union A, Faulk KN, Bukh J, Emerson SU, Purcell RH. · Molecular Hepatitis Section, LID, NIAID, NIH, Bldg. 50, Rm. 6537, 50 South Dr., MSC 8009, Bethesda, MD 20892-8009, USA. · J Virol. · Pubmed #17977972 links to  free full text

Abstract: The relative importance of humoral and cellular immunity in the prevention or clearance of hepatitis C virus (HCV) infection is poorly understood. However, there is considerable evidence that neutralizing antibodies are involved in disease control. Here we describe the detailed analysis of human monoclonal antibodies (MAbs) directed against HCV glycoprotein E1, which may have the potential to control HCV infection. We have identified two MAbs that can strongly neutralize HCV-pseudotyped particles (HCVpp) bearing the envelope glycoproteins of genotypes 1a, 1b, 4a, 5a, and 6a and less strongly neutralize HCVpp bearing the envelope glycoproteins of genotype 2a. Genotype 3a was not neutralized. The epitopes for both MAbs were mapped to the region encompassing amino acids 313 to 327. In addition, robust neutralization was also observed against cell culture-adapted viruses of genotypes 1a and 2a. Results from this study suggest that these MAbs may have the potential to prevent HCV infection.

Shata MT, Barrett A, Shire NJ, Abdelwahab SF, Sobhy M, Daef E, El-Kamary SS, Hashem M, Engle RE, Purcell RH, Emerson SU, Strickland GT, Sherman KE. · Internal Medicine, Division of Digestive Diseases, University of Cincinnati, Cincinnati, OH 45267-0595, USA. · J Immunol Methods. · Pubmed #17905301 links to  free full text

Abstract: In developing countries, hepatitis E (HEV) and hepatitis A (HAV) are the major causes of acute viral hepatitis with similar feco-oral modes of transmission. In contrast to the high seroprevalence of hepatitis A infection, a low seroprevalence of HEV among children in endemic areas has been reported. These data suggest the possibility that silent HEV infection is undiagnosed by the current available methods. Many of the serological tests used for HEV diagnosis have poor specificity and are unable to differentiate among different genotypes of HEV. Moreover, the RT-PCR used for HEV isolation is only valid for a brief period during the acute stage of infection. Cell-mediated immune (CMI) responses are highly sensitive, and long lasting after sub-clinical infections as shown in HCV and HIV. Our objective was to develop a quantitative assay for cell-mediated immune (CMI) responses in HEV infection as a surrogate marker for HEV exposure in silent infection. Quantitative assessment of the CMI responses in HEV will also help us to evaluate the role of CMI in HEV morbidity. In this study, an HEV-specific interferon-gamma (IFN-gamma) ELISPOT assay was optimized to analyze HEV-specific CMI responses. We used peripheral blood mononuclear cells (PBMC) and sera from experimentally infected chimpanzees and from seroconverted and control human subjects to validate the assay. The HEV-specific IFN-gamma ELISPOT responses correlated strongly and significantly with anti-HEV ELISA positive/negative results (rho=0.73, p=0.02). Moreover, fine specificities of HEV-specific T cell responses could be identified using overlapping HEV ORF2 peptides.

Sakai A, Takikawa S, Thimme R, Meunier JC, Spangenberg HC, Govindarajan S, Farci P, Emerson SU, Chisari FV, Purcell RH, Bukh J. · Hepatitis Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8009, USA. · J Virol. · Pubmed #17409145 links to  free full text

Abstract: Both viral and host factors are thought to influence the pathogenesis of hepatitis C virus (HCV) infection. We studied strain HC-TN (genotype 1a), which caused fulminant hepatic failure in a patient and, subsequently, severe hepatitis in a chimpanzee (CH1422), to analyze the relationship between disease severity, host immune response, viral evolution, and outcome. A second chimpanzee (CH1581) was infected from CH1422 plasma, and a third chimpanzee (CH1579) was infected from RNA transcripts of a consensus cDNA of HC-TN (pHC-TN). RNA transcripts of pHC-TN did not replicate in Huh7.5 cells, which were recently found to be susceptible to infection with another fulminant HCV strain (JFH1). The courses of viremia were similar in the three animals. However, CH1581 and CH1579 developed a less severe acute hepatitis than CH1422. CH1579 and CH1422 resolved the infection, whereas CH1581 became persistently infected. CH1579 and CH1581, despite their differing outcomes, both developed significant intrahepatic cellular immune responses, but not antibodies to the envelope glycoproteins or neutralizing antibodies, during the acute infection. We analyzed the polyprotein sequences of virus recovered at five and nine time points from CH1579 and CH1581, respectively, during the first year of follow-up. High mutation rates and high proportions of nonsynonymous mutations suggested immune pressure and positive selection in both animals. Changes were not selected until after the initial decrease in virus titers and after the development of immune responses and hepatitis. Subsequently, however, mutations emerged repeatedly in both animals. Overall, our results indicate that disease severity and outcome of acute HCV infection depend primarily on the host response.

Yu C, Zimmerman C, Stone R, Engle RE, Elkins W, Nardone GA, Emerson SU, Purcell RH. · Laboratory of Infectious Diseases, Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, Building 50, Bethesda, MD 20892-8009, USA. · J Virol Methods. · Pubmed #17336401 No free full text.

Abstract: Recent reports from Japan implicated wild Sika deer (Cervus nippon) in the zoonotic transmission of hepatitis E to humans. Seroprevalence studies were performed to determine if imported feral populations of Sika deer in Maryland and Virginia posed a similar risk of transmitting hepatitis E virus (HEV). Hunters collected blood on filter paper discs from freshly killed deer. The discs were desiccated and delivered to a collection point. The dried filters were weighed to estimate the amount of blood absorbed and were eluted and collected in one tube via a novel extraction system. The procedure was quantified and validated with negative and positive serum and blood samples obtained from domestic Sika deer before and after immunization with HEV recombinant capsid protein, respectively. None of the 155 tested samples contained antibody to HEV, suggesting that Sika deer in these populations, unlike those in Japan, do not pose a significant zoonotic threat for hepatitis E. However, the new method developed for collecting and eluting the samples should prove useful for field studies of many other pathogens.

Zhou YH, Chen Z, Purcell RH, Emerson SU. · Laboratory of Infectious Diseases, Hepatitis Viruses and Molecular Hepatitis Sections, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. · Immunol Cell Biol. · Pubmed #17130902 No free full text.

Abstract: Epitope mapping (identification of an antigenic site recognized by an antibody) is an important component of vaccine development and immunological assays. It is widely accepted that in Western blots, antibodies react exclusively with continuous epitopes: discontinuous epitopes are assumed to be irreversibly destroyed by electrophoresis under the denaturing conditions used for sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Here, we demonstrate that the epitopes recognized by four different monoclonal antibodies were identified as discontinuous epitopes when characterized by radioimmunoprecipitation assays and enzyme-linked immunosorbent assays, yet each of these antibodies reacted with the corresponding antigen on Western blots. Reaction on Western blots may be due to epitope renaturation during or after the transfer of the protein to a membrane. Therefore, positive reactions on Western blots do not necessarily indicate that epitopes are continuous and this caveat should be kept in mind while characterizing them.

Emerson SU, Nguyen H, Torian U, Purcell RH. · Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 50, Room 6537, 50 South Drive, MSC 8009, Bethesda, MD 20892, USA. · J Virol. · Pubmed #16928762 links to  free full text

Abstract: A subclone of Huh-7 cells that could be relatively efficiently transfected and infected with hepatitis E virus was identified. Following transfection, infectious virus was produced but remained predominantly cell associated. Intracellular virus, recovered by lysis of transfected cells, infected naïve cells. This in vitro-produced virus appeared to be antigenically identical to virus isolated from clinical samples. Lysates from cells transfected with mutant viral genomes unable to synthesize ORF3 protein contained infectious virions that were similar in number, thermostability, and sedimentation characteristics to those in lysates transfected with wild-type viral genomes. Therefore, in contrast to its requirement in vivo, ORF3 protein is not required for infection of Huh-7 cells or production of infectious virus in vitro.

Graff J, Torian U, Nguyen H, Emerson SU. · Molecular Hepatitis Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8009, USA. · J Virol. · Pubmed #16731930 links to  free full text

Abstract: Hepatitis E virus replicons containing the neomycin resistance gene expressed from open reading frames (ORFs) 2 and 3 were transfected into Huh-7 cells, and stable cell lines containing functional replicons were selected by constant exposure to G418 sulfate. Northern blot analyses detected full-length replicon RNA and a single subgenomic RNA. This subgenomic RNA, which was capped, initiated at nucleotide 5122 downstream of the first two methionine codons in ORF3 and was bicistronic; two closely spaced methionine codons in different reading frames were used for the initiation of ORF3 and ORF2 translation.

Takikawa S, Engle RE, Emerson SU, Purcell RH, St Claire M, Bukh J. · Hepatitis Viruses and Molecular Hepatitis Sections, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. · Proc Natl Acad Sci U S A. · Pubmed #16492760 links to  free full text

Abstract: GB virus B (GBV-B), which infects tamarins, is the virus most closely related to hepatitis C virus (HCV). HCV has a protein (p7) that is believed to form an ion channel. It is critical for viability. In vitro studies suggest that GBV-B has an analogous but larger protein (p13). We found that substitutions of the -1 and/or -3 residues of the putative cleavage sites (amino acid 613/614 and 732/733) abolished processing in vitro and rendered an infectious GBV-B clone nonviable in tamarins. Internal cleavage was predicted at two sites (amino acid 669/670 and 681/682), and in vitro analysis indicated processing at both sites, suggesting that p13 is processed into two components (p6 and p7). Mutants with substitution at amino acid 669 or 681 were viable in vivo, but the recovered viruses had changes at amino acid 669 and 681, respectively, which restored cleavage. A mutant lacking amino acid 614-681 (p6 plus part of p7) was nonviable. However, a mutant lacking amino acid 614-669 (p6) produced high titer viremia and acute resolving hepatitis; viruses recovered from both animals lacked the deleted sequence and had no other mutations. Thus, p6 was dispensable but p7 was essential for infectivity. The availability of a recombinant GBV-B virus containing a p7 protein with similarities to the HCV p7 will enhance the relevance of this model and will be of importance for identifying compounds that inhibit p7 function as additional therapeutic agents.

Emerson SU, Clemente-Casares P, Moiduddin N, Arankalle VA, Torian U, Purcell RH. · Molecular Hepatitis and Hepatitis Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive MSC-8009, Bethesda, MD 20892-8009, USA. · J Gen Virol. · Pubmed #16476993 links to  free full text

Abstract: Monolayers of Hep G2/C3A cells were inoculated with genotype 1 Hepatitis E virus (HEV) mixed with either anti-HEV or an appropriate control. After 5 or 6 days, cell monolayers were stained with anti-HEV and infected cells were identified by immunofluorescence microscopy and counted. Anti-HEV from vaccinated or infected rhesus monkeys neutralized the virus, as did mAbs that recognized epitopes on the C terminus of a recombinant vaccine protein. Antibodies were broadly cross-reactive, since convalescent serum from animals infected with any one of the four mammalian genotypes all neutralized the genotype 1 virus.

Meky FA, Stoszek SK, Abdel-Hamid M, Selim S, Abdel-Wahab A, Mikhail N, El-Kafrawy S, El-Daly M, Abdel-Aziz F, Sharaf S, Mohamed MK, Engle RE, Emerson SU, Purcell RH, Fix AD, Strickland GT. · Department of Community, Environmental and Occupational Medicine, Ain Shams University, Cairo, Egypt. · Clin Infect Dis. · Pubmed #16447107 No free full text.

Abstract: BACKGROUND: Acute viral hepatitis is less frequent in Egypt than serum antibody levels suggest. Because acute viral hepatitis has a wide clinical spectrum, we tested the hypothesis that many cases are undetected because of mild illness caused by initial, early-childhood exposure to hepatitis viruses. METHODS: During active case detection among 20,000 inhabitants of rural villages in Egypt, we screened 1715 symptomatic patients for serum alanine aminotransferase (ALT) levels. Viral hepatitis markers were tested in 47 subjects who had ALT levels that were least twice the normal level. RESULTS: Of the 47 individuals tested, 4 children aged 3-5 years had immunoglobulin M (IgM) antibodies to hepatitis A virus (anti-HAV IgM). One also had a possible false-positive result to a test for IgM antibodies to hepatitis E virus. None had serological evidence of acute hepatitis B virus (HBV) infection or hepatitis C virus (HCV) infection. However, 33 of the remaining 43 had active HCV infection, having both antibodies to HCV (anti-HCV) and HCV RNA. Four others anti-HCV without HCV RNA, and 2 others had seroconversion to anti-HCV during follow-up. Two patients who were positive for hepatitis B surface antigen had chronic HBV infection. Only 3 with elevated ALT levels had no evidence of acute or chronic infections with known hepatitis viruses. Immunoglobulin G antibodies to hepatitis E virus was detected in 40 patients. CONCLUSION: Active surveillance covering approximately 50,000 person-years detected only 4 cases of acute HAV infection. Almost all persons with mild symptoms and elevated ALT levels had serological evidence of chronic viral hepatitis, most often associated with HCV. Many of these cases were probably "flare-ups" of HCV infection or incidental illness in patients with chronic HCV infection, but some could have been caused by difficult-to-confirm initial HCV infections. Although serological evidence for exposures was highly prevalent, hepatitis viruses seldom caused acute viral hepatitis in these communities.

Stoszek SK, Engle RE, Abdel-Hamid M, Mikhail N, Abdel-Aziz F, Medhat A, Fix AD, Emerson SU, Purcell RH, Strickland GT. · International Health Division, Department of Epidemiology and Preventive Medicine, School of Medicine, University of Maryland, 660 W. Redwood Street, Baltimore, MD 20201, USA. · Trans R Soc Trop Med Hyg. · Pubmed #16257427 No free full text.

Abstract: Hepatitis E virus (HEV) is enterically transmitted and causes self-limiting acute viral hepatitis (AVH) primarily in less developed countries. A prospective cohort study to assess incidence of, and risk factors for, seroconversion to HEV (anti-HEV) was conducted in two Egyptian villages with a 67.7% anti-HEV prevalence. Nine hundred and nineteen villagers who were initially anti-HEV-negative were followed for 10.7 months. Thirty-four (3.7%) had strong anti-HEV serologic responses at follow-up giving an estimated anti-HEV incidence of 41.6/1,000 person-years. No significant associations were found between anti-HEV seroincidence and demographic and socioeconomic factors, source of water, household plumbing or sanitation, hand and vegetable washing, ownership of animals, jaundice and many other variables. None of the seroconverting subjects gave a history compatible with AVH during the interval. We hypothesize that both zoonotic and anthroponotic transmission of avirulent (possibly genotype-3) HEV is occurring extensively in these rural villages. An alternative explanation for the lack of morbidity among anti-HEV incident cases could be initial asymptomatic infections occur during early childhood with subsequent antibody titer boosting without illness upon re-exposure to the virus.

Stoszek SK, Abdel-Hamid M, Saleh DA, El Kafrawy S, Narooz S, Hawash Y, Shebl FM, El Daly M, Said A, Kassem E, Mikhail N, Engle RE, Sayed M, Sharaf S, Fix AD, Emerson SU, Purcell RH, Strickland GT. · International Health Division, Department of Epidemiology and Preventive Medicine, School of Medicine, University of Maryland, 660W. Redwood Street, Baltimore, MD 20201, USA. · Trans R Soc Trop Med Hyg. · Pubmed #16257426 No free full text.

Abstract: The epidemiology of hepatitis E virus (HEV), an enterically-transmitted cause of acute viral hepatitis (AVH), is not fully understood. During outbreaks on the Indian subcontinent and elsewhere, HEV causes severe AVH with mortality rates around 20% during pregnancy. In Egypt, where prevalence of HEV antibodies (anti-HEV) in rural communities is very high, severe HEV-caused AVH in pregnant women has not been reported. This study examined a cohort of 2,428 pregnant women in the Nile Delta to assess prevalence of, and risk factors for, anti-HEV and correlated these with history of liver disease. Anti-HEV prevalence was 84.3%. Several risk factors associated with anti-HEV included older age, many siblings, not using soap to wash produce and frequent contact with cats. History of jaundice and liver disease was rare and not increased in those having anti-HEV. Our results confirm Egypt's high HEV endemicity and show that almost all women of childbearing age in these communities had prior HEV exposures without a history of liver disease. Reasons for the lack of clinical hepatitis remain unclear but could be the result of early childhood HEV exposures, producing long-lasting immunity and/or modify subsequent responses to exposure. Alternatively, the predominant HEV strain(s) in Egypt are less virulent than those in South Asia.

Schofield DJ, Bartosch B, Shimizu YK, Allander T, Alter HJ, Emerson SU, Cosset FL, Purcell RH. · Hepatitis Viruses Section, Laboratory of Infectious Diseases, NIAID, National Institutes of Health, Bethesda, MD 20892-8009, USA. · Hepatology. · Pubmed #16250048 No free full text.

Abstract: Active and/or passive immunoprophylaxis against hepatitis C virus (HCV) remain unachieved goals. Monoclonal antibodies might provide one approach to protection. We derived human monoclonal antibodies from the bone marrow of a patient with a well-controlled HCV infection of 22 years duration. Five distinct antibodies reactive with the E2 glycoprotein of the homologous 1a strain of HCV were recovered as antigen-binding fragments (FAbs). They demonstrated affinity constants as high as 2 nanomolar. "Neutralization of binding" titers paralleled the affinity constants. All five FAbs reacted with soluble E2 protein only in nonreducing gels, indicating that the relevant epitopes were conformational. The FAbs could be divided into two groups, based on competition analysis. Three of the FAbs neutralized the infectivity of pseudotyped virus particles (pp) bearing the envelope glycoproteins of the homologous HCV strain (genotype 1a). The three FAbs also neutralized genotype 1b pp and one also neutralized genotype 2a pp. In conclusion, one or more of these monoclonal antibodies may be useful in preventing infections by HCV belonging to genotype 1 or 2, the most medically important genotypes worldwide.

Emerson SU, Arankalle VA, Purcell RH. · Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-8009, USA. · J Infect Dis. · Pubmed #16088844 No free full text.

Abstract: The thermal stability of virulent hepatitis E virus (HEV) and hepatitis A virus (HAV) was compared. Fecal suspensions of virus were heated to temperatures between 45 degrees C and 70 degrees C, and residual infectivity was determined in a cell culture system that was permissive for both viruses. Although HEV was less stable than was HAV, some HEV would most likely survive the internal temperatures of rare-cooked meat.

Graff J, Nguyen H, Yu C, Elkins WR, St Claire M, Purcell RH, Emerson SU. · Molecular Hepatitis Section, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892-8009, USA. · J Virol. · Pubmed #15890906 links to  free full text

Abstract: An infectious cDNA clone of hepatitis E virus was mutated in order to prevent synthesis of either open reading frame 2 (ORF2) protein or ORF3 protein. HuH-7 cells transfected with an ORF2-null mutant produced ORF3, and those transfected with an ORF3-null mutant produced ORF2. Silent mutations introduced into a highly conserved nucleotide sequence in the ORF3 coding region eliminated the synthesis of both ORF2 and ORF3 proteins, suggesting that it comprised a cis-reactive element. A mutant that was not able to produce ORF3 protein did not produce a detectable infection in rhesus macaques. However, a mutant that encoded an ORF3 protein lacking a phosphorylation site reported to be critical for function was able to replicate its genome in cell culture and to induce viremia and seroconversion in rhesus monkeys, suggesting that phosphorylation of ORF3 protein was not necessary for genome replication or for production of infectious virions.

Zhou YH, Purcell RH, Emerson SU. · Hepatitis Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive MSC-8009, Bethesda, MD 20892, USA. · Vaccine. · Pubmed #15837215 No free full text.

Abstract: A candidate hepatitis E vaccine is composed of amino acids (aa) 112-607 of the 660-aa protein encoded by open reading frame 2 (ORF2) of hepatitis E virus (HEV). We have studied the antibody response to vaccine-associated epitopes and to epitopes excluded from the vaccine to determine if important epitopes were omitted from the vaccine and if antibody responses to these regions could be used to differentiate between infection and vaccination. ELISAs were developed based on genotype 1 ORF2 peptides, containing aa 112-607 (vaccine), 458-607 (minimum neutralization site), 1-111 (N-terminus) and 607-660 (C-terminus), as well as on ORF3 peptides, containing aa 1-123 (complete) and 91-123 (C-terminus). All naive macaques infected with HEV genotype 1, 2, 3 or 4 produced antibodies to all ORF2 peptides. Anti-ORF3 was detected in both monkeys infected with genotype 1 virus and in one of two infected with genotype 2 virus. These antibody responses were considerably weaker than those directed against the neutralization site. In contrast, vaccinated animals that were challenged with HEV had a diminished or absent immune response to the peptides not included in the vaccine. Thus, only minor epitopes were excluded from the vaccine; they had limited utility for distinguishing between vaccination and infection.