anti-HEV IgA Research Articles

The Diagnosis, Pathophysiology, and Treatment of Chronic Hepatitis E Virus Infection—A Condition Affecting Immunocompromised Patients

Hepatitis E is a zoonosis caused by hepatitis E virus (HEV), which was first discovered 40 years ago. Twenty million HEV infections worldwide are estimated each year. Most hepatitis E cases are self-limiting acute hepatitis, but the virus has been recognized to cause chronic hepatitis. Following the first case report of chronic hepatitis E (CHE) in a transplant recipient, CHE has recently been identified as associated with chronic liver damage induced by HEV genotypes 3, 4, and 7—usually in immunocompromised patients such as transplant recipients. In addition, patients infected with HIV and those receiving chemotherapy for malignancy, along with patients with rheumatic disease and COVID-19, have recently been reported as having CHE. CHE can be easily misdiagnosed by usual diagnostic methods of antibody response, such as anti-HEV IgM or IgA, because of the low antibody response in the immunosuppressive condition. HEV RNA should be evaluated in these patients, and appropriate treatments—such as ribavirin—should be given to prevent progression to liver cirrhosis or liver failure. While still rare, cases of CHE in immunocompetent patients have been reported, and care must be taken not to overlook these instances. Herein, we conduct an overview of hepatitis E, including recent research developments and management of CHE, in order to improve our understanding of such cases. The early diagnosis and treatment of CHE should be performed to decrease instances of hepatitis-virus-related deaths around the world.

Calibrating Hepatitis E Virus Serological Assays Using Asymptomatic Specimens Obtained in Japan.

ABSTRACTThis study aimed to calibrate hepatitis E virus (HEV) serological assays. We optimized the previously developed in-house HEV antibody enzyme-linked immunosorbent assay (ELISA) by setting the cutoff with an in-house serological performance panel consisting of broad HEV antibody titers and subtracting nonspecific background values for anti-HEV IgM, IgA, and IgG. We also compared the assay’s performance with that of commercial serological assay kits (four kits for IgM, one for IgA, and two for IgG). Although all serological assays readily detected HEV antibodies at high titers in the symptomatic hepatitis E population, considerable variations between assays were observed in the asymptomatic population. The in-house ELISA showed a higher sensitivity for HEV IgM, IgA, and IgG than the commercial kits and detected the seroconversion of HEV IgM and IgG earlier when testing a commercially available HEV seroconversion panel. The low sensitivity of the commercial kits was due to the high setting of the original cutoff, which was demonstrated by receiver operating characteristic analysis. However, the corrected cutoff value reduced assay specificity. Background subtraction is essential to achieve high specificity because the in-house ELISA without background subtraction reduced its specificity. These results indicate that asymptomatic specimens and background subtraction contribute to the optimization of HEV serological assays.IMPORTANCE Accurate diagnosis of hepatitis E virus (HEV) infection is essential for public health surveillance and for preventing HEV-contaminated blood transfusion. Anti-HEV IgM or IgA is used as a reliable marker of recent HEV infection. However, considerable variability in the sensitivity and specificity of HEV antibody detection is observed among several commercially available assay kits. In addition, none of the HEV antibody detection methods have been approved by the U.S. Food and Drug Administration (FDA). Here, we show that the in-house enzyme-linked immunosorbent assay (ELISA) could detect HEV IgM and IgA more sensitively than commercial kits in the asymptomatic population. We also suggest that the assay performance of commercial kits might be improved by optimizing the cutoff and reducing nonspecific background noise. A sensitive serological (IgM or IgA) assay in addition to HEV RNA testing will contribute to accurate diagnosis of acute HEV infection because HEV RNA-positive duration is relatively short.

Hepatitis E virus prevalence among blood donors in Dali, China

BackgroundHepatitis E virus (HEV) is a nonenveloped RNA virus causing hepatitis E worldwide. The increase in transfusion-transmitted cases of HEV infections from asymptomatic blood donors causing serious illnesses among immunosuppressed recipients has been reported in the past few years. China is one of the most prevalent regions of HEV; as a result, it is important to evaluate the risk of transfusion-transmitted HEV.MethodsA total of 1864 serum samples (including demographic characteristics) from blood donors were randomly collected from February to March 2018 in Dali city. Anti-HEV IgG, IgM and IgA antibodies and HEV antigen were examined by enzyme-linked immunosorbent assay (ELISA). HEV RNA was detected by real-time PCR. Multivariable logistic regression modelling was used to examine the risk factors associated with HEV prevalence.ResultsOverall, the positive rates of anti-HEV IgG, IgM, and IgA antibodies were 13.36% (249/1864), 1.13% (21/1864), and 1.82% (34/1864), respectively. However, none of the 1864 serum samples were HEV antigen positive or HEV RNA positive. Females (16.69%) had a significantly higher HEV seroprevalence than males (13.04%) (odds ratio [OR] 1.34 [95% CI, 1.02–1.75]). Bai (18.85%) donors had a significantly higher HEV seroprevalence than Han (12.21%) blood donors (odds ratio [OR], 1.65 [95% CI, 1.24–2.19] for Bai).ConclusionsHEV showed a seroprevalence among blood donors in Yunnan Province, some of which were even recent infections, indicating a threat to the safety of blood transfusions. Whether to formulate a strategy for HEV screening in blood centres needs further research.

Loss of Anti-Hepatitis E Virus Antibodies in Organ Transplant Patients with Hepatitis E

Background: To date, no reports exist regarding changes in anti-hepatitis E virus (HEV) antibodies after HEV infection in organ transplant patients. We followed up participants in a previously reported “Japanese national survey of Hepatitis E in liver, heart, and kidney transplant patients” from 2012 to 2017, to clarify HEV infection trends. Methods: Data on 106 transplant patients that were included in the current study; 32 liver, seven heart, and 67 kidney transplant recipients in 16 institutes in Japan were examined for immunoglobulin G (IgG), IgM, IgA classes of anti-HEV antibodies, and HEV RNA in the serum. Two, one, and five liver, heart, and kidney transplant patients, respectively, in whose serum HEV RNA was identified were examined. Furthermore, 30, six, and 62 liver, heart, and kidney transplant patients, respectively, positive for anti-IgG-HEV antibody were also examined. In each patient, HEV RNA, anti-HEV IgA antibody, anti-HEV IgM antibody, and anti-HEV IgG antibody titres were measured. Findings: Of eight patients with hepatitis E who were positive for HEV RNA, one (14·0%) had anti-IgG-HEV antibody negative conversion. Contrariwise, of 98 patients that were negative for HEV RNA, 24 (24·5%) had anti-HEV IgG antibody negative conversion. Of 24 patients, eight, 12, and four were liver, kidney, and heart transplant patients, respectively. Interpretation: Anti-HEV IgG antibody loss may occur unexpectedly with high frequency in transplanted patients with past HEV infection. Therefore, the possibility of HEV re-infection in transplanted patients exists, and care should be taken to prevent this. Funding: This research was supported by AMED (Grant Number JP19fk0210043). Declaration of Interests: None declared. Ethical Approval Statement: The date of birth, sex, date of transplantation, and number of immunosuppressant were extracted from the medical records. This research was approved by the Ethics Committee at our centre and at each patient's institution (IB1811). All the recipients gave written informed consent to participate in this study.

Prevalence and characteristics of hepatitis E virus infection in kidney transplant recipients: A single-center experience in Japan.

Hepatitis E virus (HEV) infection can lead to chronic hepatitis in solid organ transplant recipients. To investigate whether HEV infection influences outcomes following kidney transplantation, we examined the prevalence of HEV infection and clinical characteristics of kidney transplant recipients in our hospital. Our cross-sectional study included 184 kidney transplant recipients. Blood samples were obtained from all patients to detect anti-HEV immunoglobulin (Ig)A, IgM, and IgG by enzyme-linked immunosorbent assay and HEV RNA by reverse transcription polymerase chain reaction. Clinical data were collected from medical charts for all patients. The prevalence of anti-HEV IgG was 8/184 (4.3%). Anti-HEV IgA, anti-HEV IgM, and HEV RNA were not detected in any patients. Compared to their anti-HEV IgG-negative counterparts, anti-HEV IgG-positive patients were significantly older at the time of transplantation, and they were more likely to receive kidneys from deceased donors. No significant differences in other characteristics such as the prevalence of primary cause of end-stage renal disease, blood transfusion, and immunosuppressive therapy use; liver and renal function; and the frequencies of hepatitis B and hepatitis C virus infection were observed according to the patients' anti-HEV IgG status. HEV infection had no significant influence on the outcomes of kidney transplantation at our institution. However, HEV infection should be recognized in kidney transplant recipients similarly as hepatitis B and hepatitis C virus infection in cases of liver dysfunction.

Hepatitis E outbreak at a nursing home for aged people in Hokkaido, Japan, between February and March 2016

BackgroundInfection with hepatitis E virus (HEV) genotypes 3 and 4 are usually asymptomatic but can occasionally result in life-threatening acute hepatitis. To date, only sporadic cases together with a few outbreaks have been documented. Seroprevalence studies with assays for the detection of HEV IgG antibodies, suggest that HEV is more prevalent than previously thought, even in non-endemic regions. ObjectivesThe aim of this study was to characterize an outbreak of hepatitis E (HE) in a nursing home for aged people between February and March 2016. Study designAfter the identification of two cases living in the same nursing home, the presence of antibodies against HEV and HEV RNA were examined in serum samples collected from the other residents and staff members to identify any additional cases. An epidemiological investigation was also carried out. ResultsOnly 4 patients showed mild symptoms such as anorexia, abdominal pain and fatigue. Among the 125 persons tested, 28 residents and one dietitian were confirmed positive for anti-HEV IgA or IgM antibodies, and/or HEV RNA. Eight samples had only IgG antibodies. Finally, 22 cases were notified with HE on the basis of the presence of IgA antibodies. All HEV isolates obtained were 99.8–100% identical and belonged to genotype 3. ConclusionHEV infections seem to be under-reported or underestimated possibly due to cases being generally asymptomatic. Testing for the presence of both anti-HEV antibodies and HEV RNA would be beneficial for both the comprehensive diagnosis of HE infections and the prevention of further infections.

Hepatitis E in blood donors: investigation of the natural course of asymptomatic infection, Germany, 2011.

Asymptomatic hepatitis E virus (HEV) infections have been found in blood donors from various European countries, but the natural course is rarely specified. Here, we compared the progression of HEV viraemia, serostatus and liver-specific enzymes in 10 blood donors with clinically asymptomatic genotype 3 HEV infection, measuring HEV RNA concentrations, plasma concentrations of alanine/aspartate aminotransferase, glutamate dehydrogenase and bilirubin and anti-HEV IgA, IgM and IgG antibodies. RNA concentrations ranged from 77.2 to 2.19×105 IU/mL, with viraemia lasting from less than 10 to 52 days. Donors showed a typical progression of a recent HEV infection but differed in the first detection of anti-HEV IgA, IgM and IgG and seropositivity of the antibody classes. The diagnostic window between HEV RNA detection and first occurrence of anti-HEV antibodies ranged from eight to 48 days, depending on the serological assay used. The progression of laboratory parameters of asymptomatic HEV infection was largely comparable to the progression of symptomatic HEV infection, but only four of 10 donors showed elevated liver-specific parameters. Our results help elucidate the risk of transfusion-associated HEV infection and provide a basis for development of screening strategies. The diagnostic window illustrates that infectious blood donors can be efficiently identified only by RNA screening.

Hepatitis E virus infection and acute-on-chronic liver failure in West Africa: a case-control study from The Gambia.

In sub-Saharan Africa, it is unknown whether hepatitis E virus (HEV) infection is a common precipitating event of acute-on-chronic liver failure (ACLF). To estimate the prevalence of HEV infection in general population and assess whether HEV is a common trigger of ACLF in cirrhotic patients in The Gambia, West Africa. We first conducted an HEV sero-survey in healthy volunteers. We then tested cirrhotic patients with ACLF (cases) and compensated cirrhosis (controls) for anti-HEV IgG as a marker of exposure to HEV, and anti-HEV IgA and HEV RNA as a marker of recent infection. We also described the characteristics and survival of the ACLF cases and controls. In the healthy volunteers (n = 204), 13.7% (95% CI: 9.6-19.2) were positive for anti-HEV IgG, and none had positive HEV viraemia. After adjusting for age and sex, the following were associated with positive anti-HEV IgG: being a Christian, a farmer, drinking water from wells, handling pigs and eating pork. In 40 cases (median age: 45 years, 72.5% male) and 71 controls (39 years, 74.6% male), ≥70% were infected with hepatitis B virus. Although hepatitis B flare and sepsis were important precipitating events of ACLF, none had marker of acute HEV. ACLF cases had high (70.0%) 28-day mortality. Hepatitis E virus infection is endemic in The Gambia, where both faecal-oral route (contaminated water) and zoonotic transmission (pigs/pork meat) may be important. However, acute HEV was not a common cause of acute-on-chronic liver failure in The Gambia.

A Nationwide Survey of Hepatitis E Virus Infection and Chronic Hepatitis E in Liver Transplant Recipients in Japan

BackgroundRecently, chronic hepatitis E has been increasingly reported in organ transplant recipients in European countries. In Japan, the prevalence of hepatitis E virus (HEV) infection after transplantation remains unclear, so we conducted a nationwide cross-sectional study to clarify the prevalence of chronic HEV infection in Japanese liver transplant recipients. MethodsA total of 1893 liver transplant recipients in 17 university hospitals in Japan were examined for the presence of immunoglobulin G (IgG), IgM and IgA classes of anti-HEV antibodies, and HEV RNA in serum. FindingsThe prevalence of anti-HEV IgG, IgM and IgA class antibodies was 2.9% (54/1893), 0.05% (1/1893) and 0% (0/1893), respectively. Of 1651 patients tested for HEV RNA, two patients (0.12%) were found to be positive and developed chronic infection after liver transplantation. In both cases, HEV RNA was also detected in one of the blood products transfused at the perioperative period. Analysis of the HEV genomes revealed that the HEV isolates obtained from the recipients and the transfused blood products were identical in both cases, indicating transfusion-transmitted HEV infection. InterpretationThe prevalence of HEV antibodies in liver transplant recipients was 2.9%, which is low compared with the healthy population in Japan and with organ transplant recipients in European countries; however, the present study found, for the first time, two Japanese patients with chronic HEV infection that was acquired via blood transfusion during or after liver transplantation.

Epidemiology of domestically acquired hepatitis E virus infection in Japan: assessment of the nationally reported surveillance data, 2007-2013.

In recent years, there has been an increase in the number of reported hepatitis E virus (HEV) infections from developed countries. To describe recent trends in notification and potential risk groups and risk factors in Japan, HEV infection cases and demographic, food consumption, clinical and laboratory data reported during 2007-2013 were analysed. In total, 530 HEV infections were reported during 2007-2013. Amongst 462 domestic cases, the mean age was 56.5 years (sd 13.9) and 80.1 % were male. Forty-three cases (9.3 %) were asymptomatic, amongst which 11 were detected from blood donations. Whilst ∼50 cases were reported annually during 2007-2011, the number of reported cases increased to 121 in 2012 and 126 in 2013. The increase was characterized by a rise in the number of domestic, symptomatic cases (P = 0.05) and cases confirmed by anti-HEV IgA detection (P < 0.01). HEV genotypes G3 and G4 were consistently dominant. The major suspected source of infection was food-borne, and the major suspected foods were pig, wild boar and deer meat. The observed increase during 2012-2013 was most likely due to the coverage of the anti-HEV IgA assay by the National Health Insurance system in Japan in October 2011 and its acceptance for surveillance purposes. However, the increase was not associated with detection of asymptomatic cases. Moreover, males aged 50-69 years remained as the high-risk group, and pork and other meats continued to be the most suspected items. Our findings indicated that HEV infection is an emerging and important public health concern in Japan.

Prevalence of hepatitis E virus in slaughter-age pigs in Scotland.

The prevalence of anti-HEV isotype-specific antibodies and viraemia were investigated in serum samples collected from slaughter-age pigs (aged 22-24 weeks) from 23 farms in Scotland. Of 176 serum samples tested, 29·0% (n=51) were anti-HEV IgG positive, 36·9% (n=65) anti-HEV IgA positive and 29·0% (n=51) anti-HEV IgM positive. Overall seroprevalence (anti-HEV IgG+ and/or IgA+ and/or IgM+) was 61·4% (n=108). HEV RNA was detected in 72/162 serum samples (44·4%). Partial sequence of ORF2 (98 nt) was obtained from eight HEV RNA-positive samples and phylogenetic analysis confirmed that they were all of genotype 3. This is the first report on the prevalence of HEV in pigs in Scotland. Given the increasing incidence of locally acquired HEV infection in the UK, evidence that HEV is a foodborne zoonosis emphasizes the need for surveillance in pigs.

Infection by Brazilian and Dutch swine hepatitis E virus strains induces haematological changes in Macaca fascicularis.

BackgroundHepatitis E virus (HEV) has been described as an emerging pathogen in Brazil and seems to be widely disseminated among swine herds. An autochthonous human case of acute hepatitis E was recently reported. To obtain a better understanding of the phenotypic profiles of both human and swine HEV strains, a experimental study was conducted using the animal model, Macaca fascicularis.MethodsSix cynomolgus monkeys (Macaca fascicularis) were inoculated intravenously with swine HEV genotype 3 that was isolated from naturally and experimentally infected pigs in Brazil and the Netherlands. Two other monkeys were inoculated with HEV genotype 3 that was recovered from Brazilian and Argentinean patients with locally acquired acute and fulminant hepatitis E. The haematological, biochemical, and virological parameters of all animals were monitored for 67 days.ResultsSubclinical hepatitis was observed in all monkeys after inoculation with HEV genotype 3 that was recovered from the infected swine and human patients. HEV RNA was detected in the serum and/or faeces of 6 out of the 8 cynomolgus monkeys between 5 and 53 days after inoculation. The mild inflammation of liver tissues and elevations of discrete liver enzymes were observed. Seroconversions to anti-HEV IgM and/or IgG were detected in 7 animals. Reactivities to anti-HEV IgA were also detected in the salivary samples of 3 animals. Interestingly, all of the infected monkeys showed severe lymphopenia and a trend toward monocytosis, which coincided with elevations in alanine aminotransferase and antibody titres.ConclusionsThe ability of HEV to cross the species barrier was confirmed for both the swine (Brazilian and Dutch) and human (Argentinean) strains, thus reinforcing the zoonotic risk of hepatitis E in South America. Cynomolgus monkeys that were infected with HEV genotype 3 developed subclinical hepatitis that was associated with haematological changes. Haematological approaches should be considered in future studies of HEV infection.

A novel indirect immunofluorescence test for the detection of IgG and IgA antibodies for diagnosis of Hepatitis E Virus infections

Hepatitis E Virus (HEV) causes epidemic infections in regions of poor hygiene in the developing world. Over the last years, however, increasing numbers of autochthonous infections in industrialized countries have been described, leading to new interest in this pathogen. Currently available serological test formats to detect IgG and IgM antibodies are mainly based on bacterially expressed ORF2 and ORF3 antigens and often give ambiguous results.The objective of this study was the development of a different assay format for HEV diagnosis—a HEV immunofluorescence test (HEV-IFT) based on mammalian cells transiently expressing recombinant HEV ORF2 protein with a simple production and staining protocol and the investigation of its performance and methodical feasibility under diagnostic laboratory conditions. 31 sera of patients at different phases of HEV infection and 40 control sera from a non-endemic region were analyzed for anti-HEV IgG, IgM, and IgA antibodies.The HEV-IFT detected successfully anti-HEV IgG and IgA, but not anti-HEV IgM antibodies. In the study group the HEV-IFT was able to confirm HEV infections and to support diagnosis when ambiguous results were obtained by commercial assays. Signal localization and staining patterns helped to gather additional information about reactive antibodies present in patient sera.In conclusion the developed IFT for the detection of anti-HEV IgG and IgA antibodies can be used for diagnosis and for the serological confirmation of HEV infections.

A nationwide survey of hepatitis E virus infection in the general population of Japan

To investigate nationwide the prevalence of hepatitis E virus (HEV) infection in the general population of Japan, serum samples were collected from 22,027 individuals (9,686 males and 12,341 females; age, mean +/- standard deviation: 56.8 +/- 16.7 years; range: 20-108 years) who lived in 30 prefectures located in Hokkaido, mainland Honshu, Shikoku, and Kyushu of Japan and underwent health check-ups during 2002-2007, and were tested for the presence of IgG, IgM, and IgA classes of antibodies to HEV (anti-HEV) by in-house ELISA and HEV RNA by nested RT-PCR. Overall, 1,167 individuals (5.3%) were positive for anti-HEV IgG, including 753 males (7.8%) and 414 females (3.4%), the difference being statistically significant (P < 0.0001). The prevalence of anti-HEV IgG generally increased with age and was significantly higher among individuals aged >or=50 years than among those aged <50 years (6.6% vs. 2.7%, P < 0.0001). Although 13 individuals with anti-HEV IgG also had anti-HEV IgM and/or anti-HEV IgA, none of them had detectable HEV RNA. The presence of HEV RNA was further tested in 50 or 49-sample minipools of sera from the remaining 22,014 individuals, and three individuals without anti-HEV antibodies tested positive for HEV RNA. The HEV isolates obtained from the three viremic individuals segregated into genotype 3 and were closest to Japan-indigenous HEV strains. When stratified by geographic region, the prevalence of anti-HEV IgG as well as the prevalence of HEV RNA or anti-HEV IgM and/or anti-HEV IgA was significantly higher in northern Japan than in southern Japan (6.7% vs. 3.2%, P < 0.0001; 0.11% vs. 0.01%, P = 0.0056; respectively).

Clinical Significance of Anti-HEV IgA in Diagnosis of Acute Genotype 4 Hepatitis E Virus Infection Negative for Anti-HEV IgM

Anti-HEV IgM is a diagnostic for recent or ongoing HEV infection. However, some patients with acute hepatitis E (AHE) negative for anti-HEV IgM in acute period were often observed in clinical practice. In this study, we constructed the anti-HEV IgA indirect ELISA assay to evaluate the significance of anti-HEV IgA. The specificity of anti-HEV IgA was 99.6%. Among 245 AHE patients, 84 samples from 84 patients were positive for HEV RNA. The positive rate of anti-HEV IgA, anti-HEV IgM and anti-HEV IgG in 84 samples positive for HEV RNA was 96.3, 97.6, and 88.1%, respectively, and no sample was negative for anti-HEV IgA and anti-HEV IgM simultaneously. Among 245 AHE patients, we found nine samples collected from nine patients in acute period were negative for anti-HEV IgM but positive for anti-HEV IgA and two samples were positive for HEV RNA. Detection of anti-HEV IgA can be a useful supplement for diagnosis of acute HEV infection especially in patients negative for anti-HEV IgM.

Serological Evidence for Hepatitis E Virus Infection in Laboratory Monkeys and Pigs in Animal Facilities in Japan

In laboratory animal facilities, monkeys and pigs are used for animal experiments, but the details of hepatitis E virus (HEV) infection in these animals are unknown. The risk of infection from laboratory animals to humans has become a concern; therefore, much attention should be paid to the handling of these animals during their care and use, including surgical procedures performed on infected animals. In this connection, serum samples collected from 916 monkeys and 77 pigs kept in 23 animal facilities belonging to the Japanese Association of Laboratory Animal Facilities of National University Corporations (JALAN) and the Japanese Association of Laboratory Animal Facilities of Public and Private Universities (JALAP) in Japan were examined for the purpose of detecting antibodies to HEV and HEV RNA by using ELISA and RT-PCR, respectively. One hundred and seven serum samples of 916 (11.7%) monkeys were positive for anti-HEV IgG, and 7 and 17 serum samples of 916 (0.8% and 5.3%) monkeys were positive for anti-HEV IgM and IgA, respectively. Thirty-six samples from 62 (58.1%) farm pigs were positive for anti-HEV IgG, whereas all samples tested from miniature pigs were negative (0/15, 0%). Seven samples from 62 (9.1%) farm pigs and 7 samples from 916 (0.8%) monkeys were positive for IgM antibody, but these HEV-IgM antibody positive serum samples were HEV-RNA negative by RT-PCR. The IgM antibody positive rate (9.1%) of farm pigs was much higher than that of monkeys (0.8%). These results suggest the relative levels of risk of HEV infection from these animals to animal handlers and researchers who work with them in laboratory animal facilities.

Evaluation of anti-hepatitis E virus (HEV) immunoglobulin A in a serological screening for HEV infection

Several formulations of serological diagnostic kits were developed recently in Japan for detecting hepatitis E virus (HEV) infection. The present study was conducted to evaluate a novel anti-HEV serological kit based on detection of class A immunoglobulin antibody (anti-HEV IgA). Serum samples from 81 acute hepatitis (AH) and 112 chronic hepatitis (CH) patients were tested for anti-HEV IgG, anti-HEV IgM, and anti-HEV IgA by enzyme immunoassay, and HEV RNA was detected by reverse transcription-polymerase chain reaction. Eight of 81 (9.9%) AH patients were positive for anti-HEV IgG; 6/81 (7.4%) were positive for anti-HEV IgM; and 3/81 (3.7%) were positive for anti-HEV IgA. HEV RNA was detected only in two patients, and both were positive for anti-HEV IgA and negative for hepatitis A, B, and C virus markers. Of 112 CH patients, reactivity to anti-HEV IgM and anti-HEV IgG was found in two and four patients, respectively. None of these six patients was positive for anti-HEV IgA or HEV RNA. For these six CH patients, serial serum samples stored during the clinical follow-up (1994-2003) were further subjected to anti-HEV IgG, IgM, IgA, and HEV RNA examinations. None of the examined stored samples was reactive for anti-HEV IgA or HEV RNA despite reactivity to anti-HEV IgM and IgG. Serological examination for anti-HEV IgA together with IgM and IgG allows sensitive and specific determination of acute or past infection with HEV. Although its prevalence is low, HEV infection must be investigated in acute hepatitis patients even in nonendemic HEV countries.

Epidemiological study of hepatitis E virus infection in European wild boars ( Sus scrofa) in Spain

Evidence of hepatitis E virus (HEV) infection in Spanish domestic pig has been reported and hence it was advisable to search for this zoonotic pathogen in wild boar populations. A total of 150 wild boar serum samples from eight geographic areas from South-Central Spain were used to investigate HEV infection in European wild boar ( Sus scrofa) by means of serology and PCR and its distribution by age, region and management system. Anti-HEV IgG, IgM and IgA were determined by an in-house ELISA. The overall seroprevalence was 42.7% (range 30.63–55.65%) and 19.6% (range 13.53–27.40%) of the animals tested positive for HEV RNA. Wild boar sequences were clustered within the genotype 3. This is the first description of HEV infection in Spanish wild boar and the results obtained may suggest a possible role of wild boar as a HEV reservoir for both domestic animals and humans.

Ongoing subclinical infection of hepatitis E virus among blood donors with an elevated alanine aminotransferase level in Japan

Ongoing subclinical infection of hepatitis E virus (HEV) has not been fully studied. In the present study, serum samples were collected from 6700 voluntary blood donors with an elevated alanine aminotransferase (ALT) level of 61-476 IU/l at a Japanese Red Cross Blood Center, and were tested for the presence of IgG, IgM and IgA classes of antibodies to HEV (anti-HEV) by in-house ELISA and HEV RNA by nested RT-PCR. Overall, 479 blood donors (7.1%) were positive for anti-HEV IgG, including 8 donors with anti-HEV IgM and 7 donors with anti-HEV IgA. Among the nine donors with anti-HEV IgM and/or anti-HEV IgA, six had detectable HEV RNA. The presence of HEV RNA was further tested in 10-sample minipools of sera from the remaining 6691 donors, and three donors including one without anti-HEV IgG were found to be positive for HEV RNA. When stratified by ALT level, the prevalence of HEV RNA was significantly higher among the 109 donors with ALT > or = 201 IU/l than among the 6591 donors with ALT of 61-200 IU/l (2.8% vs. 0.1%, P < 0.0001). The HEV isolates obtained from the nine viremic donors segregated into genotype 3, shared a wide range of identities of 85.6-98.5% and were 87.3-93.9% similar to the Japan-indigenous HEV strain (JRA1), in the 412-nucleotide sequence of open reading frame 2. This study suggests that approximately 3% of Japanese individuals with ALT > or = 201 IU/l have ongoing subclinical infection with various HEV strains.

Significance of serum IgA in patients with acute hepatitis E virus infection

To study the significance of serum anti-hepatitis E virus (HEV) IgA in patients with hepatitis E. A new method was established to assay anti-HEV IgA, which could be detected in the middle phase of the infection. We compared anti-HEV IgA assay with anti-HEV IgM and anti-HEV IgG assay in sera from 60 patients with positive HEV-RNA. The 60 patients with positive HEV-RNA had both anti-HEV IgA and anti-HEV IgM and 410 patients with negative HEV-RNA were used as control. Periodic serum samples obtained from 60 patients with hepatitis E were tested for HEV RNA, anti-HEV IgM, anti-HEV IgA and anti-HEV IgG. Their HEV-RNA was detectable in the serum until 20 +/- 11 d. We used anti-HEV IgM and anti-HEV IgA assay to detect HEV infection and positive results were found in 90 +/- 15 d and 120 +/- 23 d respectively, the positive rate of anti-HEV IgA was higher than that of anti-HEV IgM and HEV-RNA (P < 0.05). The duration of anti-HEV IgA in serum is longer than that of anti-HEV IgM, and anti-HEV IgA assay is a good method to detect HEV infection.