Expression and immunogenicity of hepatitis E virus-like particles based on recombinant truncated ORF2 capsid protein.

Hepatitis E is an emerging zoonotic disease, posing a severe threat to public health in the world. Since there are no specific treatments available for HEV infection, it is crucial to develop vaccine to prevent this infection. In this study, the truncated ORF2 encoded protein of 439aa∼617aa (HEV3-179) from HEV CCJD-517 isolates was expressed as VLPs in E. coli with diameters of approximate 20 nm. HEV3-179 protein was immunized with mice, and the results showed that a higher titre of antibody was induced in NIH mice in comparison with that of KM mice (P < 0.01) and BALB/c mice (P < 0.01). The induced antibody titer is much higher in subcutaneous immunization mice than that in the mice inoculated via abdominal immunization (P < 0.05) and muscles immunization (P < 0.01). Mice immunized with 12 µg and 6 µg candidate vaccine induced higher level of antibody titer than that of 3 µg dosage group (P < 0.01, P < 0.05). Antibody change curve showed that HEV IgG antibody titer increased from 14 days post immunization (dpi) to 1:262144 and reached the peak level on 42 dpi before gradually retreated with the same level antibody titer with 1:131072 until 84 dpi. Mice inoculated with HEV3-179 produced higher titer of cytokines than the mock group, and the concentration of IL-1ß (P < 0.01) and IFN-γ (P < 0.01) further increased after stimulated by candidate vaccine. The result indicated that HEV3-179 possesses good immunogenicity, which could be used as a potential candidate for future HEV vaccine development.

Induction of Hepatitis E Virus Anti-ORF3 Antibodies from Systemic Administration of a Muscle-Specific Adeno-Associated Virus (AAV) Vector.

The hepatitis E virus (HEV) is a major global health problem, leading to large outbreaks in the developing world and chronic infections in the developed world. HEV is a non-enveloped virus, which circulates in the blood in a quasi-enveloped form. The quasi-envelope protects HEV particles from neutralising anti-capsid antibodies in the serum; however, most vaccine approaches are designed to induce an immune response against the HEV capsid. In this study, we explored systemic in vivo administration of a novel synthetic and myotropic Adeno-associated virus vector (AAVMYO3) to express the small HEV phosphoprotein ORF3 (found on quasi-enveloped HEV) in the musculature of mice, resulting in the robust and dose-dependent formation of anti-ORF3 antibodies. Neutralisation assays using the serum of ORF3 AAV-transduced mice showed a modest inhibitory effect on the infection of quasi-enveloped HEV in vivo, comparable to previously characterised anti-ORF3 antibodies used as a control. The novel AAVMYO3 capsid used in this study can serve as a versatile platform for the continued development of vector-based vaccines against HEV and other infectious agents, which could complement traditional vaccines akin to the current positive experience with SARS-CoV-2.

Hepatitis E virus infection activates NOD-like receptor family pyrin domain-containing 3 inflammasome antagonizing interferon response but therapeutically targetable.

BACKGROUND AND AIMS: HEV infection is the most common cause of liver inflammation, but the pathogenic mechanisms remain largely unclear. We aim to explore whether HEV infection activates inflammasomes, crosstalk with antiviral interferon response, and the potential of therapeutic targeting. APPROACH AND RESULTS: We measured IL-1ß secretion, the hallmark of inflammasome activation, in serum of HEV-infected patients and rabbits, and in cultured macrophage cell lines and primary monocyte-derived macrophages. We found that genotypes 3 and 4 HEV infection in rabbits elevated IL-1ß production. A profound increase of IL-1ß secretion was further observed in HEV-infected patients (1,733 ± 1,234 pg/mL; n = 70) compared to healthy persons (731 ± 701 pg/mL; n = 70). Given that macrophages are the drivers of inflammatory response, we found that inoculation with infectious HEV particles robustly triggered NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation in primary macrophages and macrophage cell lines. We further revealed that the ORF2 capsid protein and the formed integral viral particles are responsible for activating inflammasome response. We also identified NF-κB signaling activation as a key upstream event of HEV-induced NLRP3 inflammasome response. Interestingly, inflammasome activation antagonizes interferon response to facilitate viral replication in macrophages. Pharmacological inhibitors and clinically used steroids can effectively target inflammasome activation. Combining steroids with ribavirin simultaneously inhibits HEV and inflammasome response without cross-interference. CONCLUSIONS: HEV infection strongly activates NLRP3 inflammasome activation in macrophages, which regulates host innate defense and pathogenesis. Therapeutic targeting of NLRP3, in particular when combined with antiviral agents, represents a viable option for treating severe HEV infection.

Hepatitis E virus infection in pigs: a first report from Zambia.

While evidence suggests presence of HEV infection in humans in Zambia, currently, there is no information on its occurrence in domestic pigs. Here, we investigated the presence of HEV antibodies and genome in domestic pigs in Zambia. Sera (n = 484) from domestic pigs were screened for antibodies against HEV by ELISA while genome detection in fecal (n = 25) and liver (n = 100) samples from slaughter pigs was conducted using nested RT-PCR assay. Overall, seroprevalence was 47.7% (231/484) while zoonotic genotype 3 HEV RNA was detected in 16.0% (20/125) of slaughtered pigs. This is the first report to highlight occurrence of HEV infection in domestic pigs in Zambia. This finding suggests possible contamination of the pork supply chain. Moreover, there is a potential risk of zoonotic transmission of HEV to abattoir workers, pig farmers and handlers.

Characterization of rabbit hepatitis E virus isolated from a feral rabbit.

Rabbit hepatitis E virus (HEV) has been detected among rabbits and recently isolated from immunocompromised patients, suggesting zoonotic transmission. In this study, HEV infection among feral rabbits (Oryctolagus cuniculus) was assessed by detection of anti-HEV antibodies and HEV RNA. The prevalence of anti-HEV antibodies in sera was of 33 % (20/60) and HEV RNA was detected from only one of fecal swabs (1.7 %, 1/58). Furthermore, one naïve rabbit was intravenously inoculated with the suspension of the HEV-positive fecal specimen, exhibiting persistent HEV shedding in feces, intermittent viremia, seroconversion to anti-HEV IgM and IgG, and high alanine aminotransferase (ALT) values, indicating persistent HEV infection. The isolate JP-59 had a length of 7,282 bp excluding a poly (A) tail and possessed the characteristic 93 bp-insertion in ORF1. Phylogenetic analysis indicated that JP-59 formed a cluster with other rabbit HEV isolates from rabbits and human origin. The JP-59 shared the nucleotide sequence identities less than 87 % with other rabbit HEVs, suggesting that a novel rabbit HEV strain was circulating in Japan.

Hepatitis E Virus Infection-Immune Responses to an Underestimated Global Threat.

Infection with the hepatitis E virus (HEV) is one of the main ubiquitous causes for developing an acute hepatitis. Moreover, chronification plays a predominant role in immunocompromised patients such as transplant recipients with more frequent severe courses. Unfortunately, besides reduction of immunosuppression and off-label use of ribavirin or pegylated interferon alfa, there is currently no specific anti-viral treatment to prevent disease progression. So far, research on involved immune mechanisms induced by HEV is limited. It is very difficult to collect clinical samples especially from the early phase of infection since this is often asymptomatic. Nevertheless, it is certain that the outcome of HEV-infected patients correlates with the strength of the proceeding immune response. Several lymphoid cells have been identified in contributing either to disease progression or achieving sustained virologic response. In particular, a sufficient immune control by both CD4+ and CD8+ T cells is necessary to prevent chronic viral replication. Especially the mechanisms underlying fulminant courses are poorly understood. However, liver biopsies indicate the involvement of cytotoxic T cells in liver damage. In this review, we aimed to highlight different parts of the lymphoid immune response against HEV and point out questions that remain unanswered regarding this underestimated global threat.

Hepatitis E in Bangladesh: Insights From a National Serosurvey.

BACKGROUND: Hepatitis E virus (HEV) genotypes 1 and 2 are a major cause of avoidable morbidity and mortality in South Asia. Despite the high risk of death among infected pregnant women, scarce incidence data has been a contributing factor to global policy recommendations against the introduction of licensed hepatitis E vaccines, one of the only effective prevention tools. METHODS: We tested serum from a nationally representative serosurvey in Bangladesh for anti-HEV immunoglobulin G and estimated seroprevalence. We used Bayesian geostatistical models to generate high-resolution maps of seropositivity and examined variability in seropositivity by individual-level, household-level, and community-level risk factors using spatial logistic regression. RESULTS: We tested serum samples from 2924 individuals from 70 communities representing all divisions of Bangladesh and estimated a national seroprevalence of 20% (95% confidence interval [CI], 17%-24%). Seropositivity increased with age and male sex (odds ratio, 2.2 male vs female; 95% CI, 1.8-2.8). Community-level seroprevalence ranged widely (0-78%) with higher seroprevalence in urban areas, including Dhaka, with a 3.0-fold (95% credible interval, 2.3-3.7) higher seroprevalence than the rest of the country. CONCLUSIONS: Hepatitis E infections are common throughout Bangladesh. Strengthening surveillance for hepatitis E, especially in urban areas, can provide additional evidence to appropriately target interventions.

Immunogenicity and Antigenicity of Rabbit Hepatitis E Virus-Like Particles Produced by Recombinant Baculoviruses.

Rabbit hepatitis E virus (HEV) is a novel HEV belonging to genotype 3 (HEV-3) in the Orthohepevirus A species of the genus Hepevirus, family Hepeviridae. Rabbit HEV was originally isolated from rabbits and found to cause zoonotic infection. Although rabbit HEV can be successfully grown in culture with several cell lines, including the human carcinoma cell line PLC/PRF/5, it is difficult to obtain the large amounts of viral antigen required for diagnosis and vaccine development. In this study, we expressed N-terminal 13 and 111 aa-truncated rabbit HEV ORF2 proteins using recombinant baculoviruses and obtained two types of virus-like particles (VLPs), RnVLPs and RsVLPs with ~35 and 24 nm diameter, respectively. Anti-rabbit HEV IgG antibodies were induced in high titer by immunizing rabbits with RnVLPs or RsVLPs. The antibody secretion in the serum persisted more than three years. RsVLPs showed stronger antigenic cross-reactivity against HEV-1, HEV-3 and HEV-4 than rat HEV. Moreover, anti-RsVLPs antibodies neutralized not only the cognate virus but also HEV-1, HEV-3 and HEV-4 ex vivo, indicating that rabbit HEV had the same serotype as human HEVs. In contrast, the antibody did not block rat HEV infection, demonstrating that rat HEV belonged to a different serotype. Animal experiments indicated that immunization with either RnVLPs or RsVLPs completely protected the rabbits from challenge by rabbit HEV, suggesting that the VLPs are candidates for rabbit HEV vaccine development.

Antigenic Characterization of ORF2 and ORF3 Proteins of Hepatitis E Virus (HEV).

To evaluate the antigenic properties of Hepatitis E Virus (HEV) Open Reading Frame 2 and 3 (ORF2 and ORF3) codified proteins, we expressed different portions of ORF2 and the entire ORF3 in E. coli, a truncated ORF2, was also expressed in baculovirus. A panel of 37 monoclonal antibodies (MAbs) was raised against ORF2 (1-660 amino acids) and MAbs were mapped and characterized using the ORF2 expressed portions. Selected HEV positive and negative swine sera were used to evaluate ORF2 and ORF3 antigens' immunogenicity. The MAbs were clustered in six groups identifying six antigenic regions along the ORF2. Only MAbs binding to the sixth ORF2 antigenic region (394-608 aa) were found to compete with HEV positive sera and efficiently catch the recombinant antigen expressed in baculovirus. The ORF2 portion from 394-608 aa demonstrated to include most immunogenic epitopes with 85% of HEV positive swine sera reacting against the region from 461-544 aa. Only 5% of the selected HEV sera reacted against the ORF3 antigen.

Prevalence and clinical correlation of hepatitis E virus antibody in the patients' serum samples from a tertiary care hospital in Thailand during 2015-2018.

BACKGROUND: Prevalence and incidence of hepatitis caused by HEV infection are usually higher in developing countries. This study demonstrated the HEV seroprevalence and incidence of HEV infection in patients with clinical hepatitis in a tertiary hospital in Thailand. METHODS: A laboratory-based cross-sectional study was conducted using 1106 serum samples from patients suspected of HEV infection sent to the Serology laboratory, Siriraj Hospital, for detecting HEV antibodies during 2015-2018. Prevalence of anti-HEV IgG and IgM antibodies in general patients, including organ transplant recipients and pregnant women in a hospital setting, were determined using indirect enzyme-linked immunosorbent assay (ELISA) kits. Comparison of laboratory data between groups with different HEV serological statuses was performed. RESULTS: HEV IgG antibodies were detected in 40.82% of 904 serum samples, while HEV IgM antibodies were detected in 11.75% of 1081 serum samples. Similar IgG and IgM antibody detection rates were found in pregnant women. Interestingly, anti-HEV IgM antibodies were detected in 38.5% of patients who underwent organ transplantation. Patients who tested positive for anti-HEV IgM antibodies had higher alanine aminotransferase levels than those who had not. In contrast, patients who tested positive for anti-HEV IgG had more elevated levels of total bilirubin than those who tested negative. CONCLUSIONS: HEV seroprevalence and incidence in patients with clinical hepatitis were relatively high in the Thai population, including the pregnancy and organ transplant subgroups. The results potentially benefit the clinicians in decision-making to investigate HEV antibodies and facilitating proper management for patients.

Limited Value of Single Sampling for IgM Antibody Determination as a Diagnostic Approach for Acute Hepatitis E Virus Infection.

The objective was to evaluate the accuracy of a single determination of IgM antibodies for hepatitis E virus (HEV) diagnosis in patients with acute hepatitis. A prospective study included patients with suspicion of HEV infection, defined as individuals with acute hepatitis showing negative results for serological and molecular markers of other hepatitis viruses. All patients were evaluated for hepatitis E virus infection, including both IgM antibodies and viral RNA determinations. Hepatitis E virus infection was defined as positivity for any of these markers. A total of 182 patients were included in the study, of whom 68 (37.4%) were diagnosed with HEV infection. Of these, 29 (42.6%) were positive for both IgM and HEV RNA, 25 (36.8%) were positive only for IgM antibodies, and 14 (20.6%) were positive only for HEV RNA. Considering only those individuals who were positive for IgM antibodies, 54 of the 68 total cases (79.4%) could be identified, showing a percentage of false-negative individuals of 20.6%. The diagnostic algorithm of hepatitis E virus infection in patients with acute hepatitis should include the determination of both IgM antibodies and HEV RNA because single sampling for IgM antibody determination led to an important proportion of misdiagnosed cases. IMPORTANCE In immunocompetent patients with a suspicion of hepatitis E virus (HEV) infection, single IgM antibody testing is typically applied. In this prospective study, we aimed to evaluate the accuracy of three different HEV screening approaches in patients with acute hepatitis, including approaches based on IgM determination, HEV RNA detection, and the combination of both. Our study shows that any diagnostic algorithm for HEV infection in patients with acute hepatitis should be based on the determination of both markers (IgM antibodies and HEV RNA) because single sampling for IgM antibodies results in an unacceptable number of false-negative results (20%). According to our results, the determination of HEV RNA should not be limited to immunosuppressed individuals because a high proportion of cases could be misdiagnosed.

[Markers of viral hepatitis E (Hepeviridae, Orthohepevirus, Orthohepevirus A) in the imported Old World monkeys].

INTRODUCTION: Viral hepatitis E is a zooanthroponotic disease that occurs in humans and various animals, including monkeys. It is caused by hepatitis E virus (HEV) (Hepeviridae, Orthohepevirus: Orthohepevirus A), for which 8 genotypes have been described to date. Among them, strains of genotypes 1 and 2 have been isolated from humans, strains of genotypes 3 and 4 from humans and animals, and strains of genotypes 5-8 from animals only. The main threat of the disease is associated with the documented zoonotic transmission of HEV genotypes 3, 4, 7, and 8, to humans through infected meat, blood and milk. Thus, monkeys could be involved in the transmission of HEV.The aim of this work was to study serological and molecular genetic markers of HEV infection in strepsirrhines (Old World monkeys, Cercopithecoidea), imported to the Adler Primate Center from various regions of the world (Tanzania, Vietnam, Mauritius). MATERIAL AND METHODS: Fecal (n = 224) and blood serum samples (n = 395) from cynomolgus (Macaca fascicularis) and vervet monkeys (Chlorocebus pygerythrus) were examined by the enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR). RESULTS AND DISCUSSION: The data obtained show the high detection rate (51.8%) of IgG antibodies to HEV among 5 groups of cynomolgus monkeys imported from Vietnam, with a predominance of highly reactive sera (84%). High detection rate of IgM antibodies in these animals (10.4%) was observed, with the large number of IgM-reactive sera in one particular group of animals (36.8%). The fact of detection of HEV RNA in two groups of cynomolgus monkeys (11.9% and 5.7%) is of particular importance. All HEV sequences of isolated from monkeys belonged to genotype 4. CONCLUSION: Our data indicate that monkeys (in particular, cynomolgus monkeys) can serve as a natural reservoir of HEV genotype 4 for humans. This requires an appropriate set of anti-epidemic measures in a number of situations.

Unusual high prevalence of antibodies to hepatitis E virus in South Brazil.

Hepatitis E virus (HEV) is worldwide distributed and might cause acute or chronic hepatitis mainly in immunocompromised individuals. In previous studies we found a high prevalence of antibodies to HEV within blood donors in south Brazil and also within backyard-raised pigs. Here, we aimed to investigate the prevalence of anti-HEV antibody and HEV RNA within the general population from three major municipalities (Caxias do Sul, Passo Fundo and Santa Maria) in south Brazil. A total of 3000 blood samples were randomly obtained from clinical laboratories at each of the three municipality (n = 1000 each) to determine the presence of anti-HEV antibodies and HEV RNA. Overall, anti-HEV antibodies were detected in 574/1000 (57,4%) samples in Caxias do Sul, 655/1000 (65.5%) samples in Passo Fundo and 554/1000 (55.4%) samples in Santa Maria. The prevalence of HEV-positive samples increased steadily and significantly (P < 0,001) with age and was unusually higher within individual over 40 years. Despite of this, none of the pooled serum samples had detectable levels of HEV RNA. The high anti-HEV antibody prevalence suggests that the virus might be present on the environment and/or foodstuff and poses a permanent threat to immune-compromised individuals.

Molybdenum Trioxide Quantum Dot-Encapsulated Nanogels for Virus Detection by Surface-Enhanced Raman Scattering on a 2D Substrate.

The use of nanogels (NGs) to modulate surface-enhanced Raman scattering (SERS) activities is introduced as an innovative strategy to address certain critical issues with SERS-based immunoassays. This includes the chemical deformation of SERS nanotags, as well as their nonspecific interactions and effective "hotspots" formation. Herein, the polymeric cocoon and stimuli-responsive properties of NGs were used to encapsulate SERS nanotags containing plasmonic molybdenum trioxide quantum dots (MoO3-QDs). The pH-controlled release of the encapsulated nanotags and their subsequent localization by maleimide-functionalized magnetic nanoparticles facilitated the creation of "hotspots" regions with catalyzed SERS activities. This approach resulted in developing a biosensing platform for the ultrasensitive immunoassays of hepatitis E virus (HEV) or norovirus (NoV). The immunoassays were optimized using the corresponding virus-like particles to attain limits of detection of 6.5 and 8.2 fg/mL for HEV-LPs and NoV-LPs, respectively. The SERS-based technique achieved a signal enhancement factor of up to ∼108 due to the combined electromagnetic and chemical mechanisms of the employed dual-SERS substrate of MoO3-QDs/2D hexagonal boron nitride nanosheets. The highlight and validation of the developed SERS-based immunoassays was the detection of NoV in infected patients' fecal specimen and clinical HEV G7 subtype. Importantly, this system can be used to maintain the stability of SERS nanotags and improve their reliability in immunoassays.

Progesterone-Mediated Enhancement of Hepatitis E Virus Replication in Human Liver Cells.

Progesterone is crucial for the maintenance of pregnancy. During pregnancy hepatitis E virus (HEV) infection is associated with increased fulminant hepatic failure and mortality rates. In this study, we determined whether progesterone modulates HEV replication and HEV-induced innate cytokine response in Huh7-S10-3 human liver cells. We first demonstrated that Huh7-S10-3 liver cells expressed SH3-domain-containing progesterone receptor membrane component (PGRMC)1/2 receptors involved in the progesterone nonclassical signaling pathway, while the classical progesterone receptor isoforms progesterone receptor-A and -B protein levels were undetectable. We showed that the genotype 3 HEV (strain P6) induced mRNA expression of type III interferon (IFN-λ1), but not other innate cytokines in Huh7-S10-3 cells. Pretreatment with progesterone at concentrations of 80 nM, 160 nM, or 480 nM, which are the physiological concentrations typically seen in the first- to third-trimester during pregnancy, significantly increased HEV replication in Huh7-S10-3 cells. However, pretreatment of cells with progesterone (80 nM) did not affect the level of HEV-induced IFN-λ1 mRNA expression. We further showed that loss of PGRMC1/2 receptors by small interfering RNA (siRNA) knockdown leads to an increase in HEV-induced IFN-λ1 expression levels at early time points via the extracellular signal-regulated kinase pathway and thus resulted in a reduced level of HEV replication. Collectively, the results indicated that progesterone-mediated modulation of HEV replication in human liver cells is plausibly through SH3-domain containing proteins such as PGRMC1/2, but not likely through immunomodulation of HEV-induced interferon response in liver cells. The results have important implications in understanding the underlying mechanisms of high mortality and fulminant hepatitis in HEV-infected pregnant women. IMPORTANCE Hepatitis E is usually a self-limiting acute disease; however, during pregnancy, a severe form of fulminant hepatic failure and high mortality rate are associated with hepatitis E virus (HEV) infection. Increased levels of progesterone and HEV RNA are observed in pregnant women with fulminant hepatic failures. Since progesterone is crucial for maintenance of pregnancy, we investigated the potential role of progesterone in HEV replication and disease pathogenesis. We demonstrated that progesterone at a concentration seen during pregnancy enhances HEV replication in human liver cells, but did not modulate HEV-induced interferon response in human liver cells. We also showed that loss of the progesterone nonclassical receptor, progesterone receptor membrane component (PGRMC)1/2, leads to a reduced level of HEV replication and an increased level of HEV-induced type III interferon (IFN-λ1) mRNA expression via the extracellular signal-regulated kinase pathway. The results from this study will aid our understanding of the underlying mechanism of pathogenesis and HEV-associated severe disease during pregnancy.

Mechanism of Cross-Species Transmission, Adaptive Evolution and Pathogenesis of Hepatitis E Virus.

Hepatitis E virus (HEV) is the leading cause of acute hepatitis worldwide. While the transmission in developing countries is dominated by fecal-oral route via drinking contaminated water, the zoonotic transmission is the major route of HEV infection in industrialized countries. The discovery of new HEV strains in a growing number of animal species poses a risk to zoonotic infection. However, the exact mechanism and the determinant factors of zoonotic infection are not completely understood. This review will discuss the current knowledge on the mechanism of cross-species transmission of HEV infection, including viral determinants, such as the open reading frames (ORFs), codon usage and adaptive evolution, as well as host determinants, such as host cellular factors and the host immune status, which possibly play pivotal roles during this event. The pathogenesis of hepatitis E infection will be briefly discussed, including the special forms of this disease, including extrahepatic manifestations, chronic infection, and fulminant hepatitis in pregnant women.

A surveillance study of hepatitis E virus infection in household cats.

Hepatitis E virus (HEV) typically causes self-limiting acute viral hepatitis, however chronic infection and extrahepatic manifestations have increasingly become a significant health problem. Domestic pigs and wild boars are the main reservoirs of HEV genotype 3 and genotype 4 for human infections in industrialized countries, although molecular and serological evidence suggest that several additional animal species may act as HEV hosts. In this study, by assessing serologically and molecularly the sera of 324 household cats from Apulia region (Italy), HEV antibodies were detected with an overall prevalence of 3.1%. Viral RNA was not detected in the sera of the animals using both HEV-specific assays and a pan-hepevirus broadly reactive set of primers for Hepeviridae. These findings document a low seroprevalence to HEV in cats in the investigated geographical setting. The exact nature of the HEV-like strains circulating in feline population remains to be established.

Multimodal investigation of rat hepatitis E virus antigenicity: Implications for infection, diagnostics, and vaccine efficacy.

BACKGROUND & AIMS: Rat hepatitis E virus (Orthohepevirus species C; HEV-C1) is an emerging cause of viral hepatitis in humans. HEV-C1 is divergent from other HEV variants infecting humans that belong to Orthohepevirus species A (HEV-A). This study assessed HEV-C1 antigenic divergence from HEV-A and investigated the impact of this divergence on infection susceptibility, serological test sensitivity, and vaccine efficacy. METHODS: Immunodominant E2s peptide sequences of HEV-A and HEV-C1 were aligned. Interactions of HEV-C1 E2s and anti-HEV-A monoclonal antibodies (mAbs) were modeled. Recombinant peptides incorporating E2s of HEV-A (HEV-A4 p239) and HEV-C1 (HEV-C1 p241) were expressed. HEV-A and HEV-C1 patient sera were tested using antibody enzymatic immunoassays (EIA), antigen EIAs, and HEV-A4 p239/HEV-C1 p241 immunoblots. Rats immunized with HEV-A1 p239 vaccine (Hecolin), HEV-A4 p239 or HEV-C1 p241 peptides were challenged with a HEV-C1 strain. RESULTS: E2s sequence identity between HEV-A and HEV-C1 was only 48%. There was low conservation at E2s residues (23/53; 43.4%) involved in mAb binding. Anti-HEV-A mAbs bound HEV-C1 poorly in homology modeling and antigen EIAs. Divergence resulted in low sensitivity of commercial antigen (0%) and antibody EIAs (10-70%) for HEV-C1 diagnosis. Species-specific HEV-A4 p239/HEV-C1 p241 immunoblots accurately differentiated HEV-A and HEV-C1 serological profiles in immunized rats (18/18; 100%) and infected-patient sera (32/36; 88.9%). Immunization with Hecolin and HEV-A4 p239 was partially protective while HEV-C1 p241 was fully protective against HEV-C1 infection in rats. CONCLUSIONS: Antigenic divergence significantly decreases sensitivity of hepatitis E serodiagnostic assays for HEV-C1 infection. Species-specific immunoblots are useful for diagnosing HEV-C1 and for differentiating the serological profiles of HEV-A and HEV-C1. Prior HEV-A exposure is not protective against HEV-C1. HEV-C1 p241 is an immunogenic vaccine candidate against HEV-C1. LAY SUMMARY: Rat hepatitis E virus (HEV-C1) is a new cause of hepatitis in humans. Using a combination of methods, we showed that HEV-C1 is highly divergent from the usual cause of human hepatitis (HEV-A). This divergence reduces the capacity of existing tests to diagnose HEV-C1 and also indicates that prior exposure to HEV-A (via infection or vaccination) is not protective against HEV-C1.

Risk of hepatitis-E virus infections among blood donors in a regional blood transfusion centre in western India.

BACKGROUND: Hepatitis-E virus (HEV) is an emerging infectious threat to blood safety. The enormity of the transmission of HEV and its clinical consequence are issues currently under debate. This study aimed to evaluate the prevalence of HEV-RNA in blood donors in western India. MATERIALS AND METHODS: We screened 13 050 blood donors for HEV using HEV-RNA screening of 10 mini-pools using RealStar HEV RT-PCR Kit (95% limit of detection (LOD): 4.7 IU/ml). Furthermore, all HEV-RNA-positive donors were investigated for the presence of IgM/IgG antibody along with liver function tests. RESULTS: Of the 13 050 blood donations, 7 (0.53%) were found to be HEV-RNA positive, and the prevalence of HEV nucleic acid testing yield cases among blood donors was 1 in 1864. All seven HEV-RNA-positive samples were tested with anti-HEV IgM and anti-HEV IgG antibodies; this resulted in two (28.5%) positive anti-HEV IgM and two (28.5%) positive anti-HEV IgG antibodies. Hepatic activity was measured, with two of seven HEV-RNA-positive donors demonstrating abnormal serum glutamic oxaloacetic transaminase (SGOT) andserum glutamic pyruvic transaminase (SGPT). Two HEV-RNA-positive blood donors who had abnormal SGOT and SGPT were found to have a high HEV viral load. Furthermore, we were able to follow up two HEV-RNA donors, and both were HEV-RNA positive and had anti-HEV IgM and anti-HEV IgG antibodies; moreover, their liver function tests were also abnormal. One of the HEV-RNA donors with high viral load did show hepatitis-E-like virus on electron microscopy. CONCLUSION: Our studies indicate that there is a significant risk of blood-borne transmission of HEV. This finding may help to provide a direction towards the safety of blood transfusions in clinical settings in countries like India, which fall under the endemic category for HEV infection.