First case of genotype 4 human hepatitis E virus infection acquired in India

Application of a truncated ORF2 protein-based ELISA for diagnosis of hepatitis E in an endemic area

Enterically transmitted waterborne hepatitis E (HE) caused due to hepatitis E virus (HEV) prevails as a significant public health problem endemic to India. Due to short-term viremia/fecal excretion and poor in vitro transmissibility of HEV, HE diagnosis depends on detection of specific IgM antibodies in serum. Present study evaluated performances of two in-house and six commercial IgM detection enzyme-linked immunosorbent assays (ELISAs) using sera collected from volunteers/acute hepatitis patients (n = 716). The in-house ELISAs were based on complete and truncated open reading frame 2 (ORF2) proteins containing neutralizing epitope/s region of genotype 1 HEV (ORF2p, 1-660 amino acid (a.a.) and T1NEp, 458-607 a.a., respectively). The commercial ELISAs included Wantai (China), MP Diagnostics (MPD) (Singapore), DIA.PRO Diagnostics (Italy), MBS (Italy), abia (Germany), and ImmunoVision (USA). T1NE ELISA showed 97.0% positive percent agreement (PPA), 99.4% negative percent agreement (NPA), and 98.6% concordance (κ = 0.97, P = 0.0000) with ORF2 ELISA. ORF2, T1NE, Wantai, and MPD ELISAs agreed on results for 88% of sera tested. Two percent sera showed reactivity in each combination of three and two of aforementioned four ELISAs. Remaining 8% sera were single ELISA reactive. PPA and NPA value ranges were 76.3-99.0% and 84.8-99.5%, respectively. Pairwise concordances between all the eight ELISAs ranged from 88.0 to 100% (κ: 0.74-1.00). Both the in-house ELISAs agreed better with Wantai over MPD ELISA. In conclusion, both ORF2 and T1NE ELISAs were equally efficient in diagnosing HEV infections. T1NEp proved to be an excellent tool in HE sero-diagnosis and is worth exploring in development of simple rapid tests. KEY POINTS: • In-house ELISA based on bacterially expressed neutralizing epitope/s region protein • In-house ELISA based on complete ORF2 protein expressed in insect cells • Comparison of two in-house and six commercial anti-HEV IgM antibody detection ELISAs.

Serology versus nucleic acid amplification to diagnose acute hepatitis E, United Kingdom, 2014-18

OBJECTIVES

Diagnosing hepatitis E infection usually involves specific IgM testing, but sensitivity/specificity concerns mean many guidelines and practices include confirmatory tests. We studied whether additional information confirmatory tests provide justifies their use.

METHODS

We examined 9,131 records of anti-hepatitis E IgM assays, 7,615 of IgG assays, and 1,726 of RT-PCR assays from our regional laboratory, spanning October 2014-October 2018. We paired 495 IgM assay results with a RT-PCR result. We examined whether IgM results predicted PCR results, reviewed discrepant pairs, and investigated the correlation between IgG and PCR results in patients with strongly reactive IgM assays.

RESULTS

Anti-hepatitis E IgM titres are bimodal. A high cut-off value optimises prediction of RNA detectability. 7/404 low-IgM samples had detectable RNA, 6 from immunosuppressed patients. 26/91 high-IgM samples did not have detectable RNA. In high-IgM samples, RNA detectability was not associated with IgG titre (one-tailed Mann-Whitney U test, p=0.14).

CONCLUSIONS

In immunocompetent patients, tests beyond IgM seldom add clinically useful information. In patients with immunocompromise, IgM and RNA could contribute information. Additional tests' extra costs/intervention delays cannot be justified. IgM assay cut-offs should reflect titres' bimodal distribution, with values standardised using international units.

Rat Hepatitis E Virus as Cause of Persistent Hepatitis after Liver Transplant

All hepatitis E virus (HEV) variants reported to infect humans belong to the species OrthohepevirusA (HEV-A). The zoonotic potential of the species OrthohepevirusC (HEV-C), which circulates in rats and is highly divergent from HEV-A, is unknown. We report a liver transplant recipient with hepatitis caused by HEV-C infection. We detected HEV-C RNA in multiple clinical samples and HEV-C antigen in the liver. The complete genome of the HEV-C isolate had 93.7% nt similarity to an HEV-C strain from Vietnam. The patient had preexisting HEV antibodies, which were not protective against HEV-C infection. Ribavirin was an effective treatment, resulting in resolution of hepatitis and clearance of HEV-C viremia. Testing for this zoonotic virus should be performed for immunocompromised and immunocompetent patients with unexplained hepatitis because routine hepatitis E diagnostic tests may miss HEV-C infection. HEV-C is also a potential threat to the blood product supply.

Genetic Variability and Evolution of Hepatitis E Virus

Hepatitis E virus (HEV) is a single-stranded positive-sense RNA virus. HEV can cause both acute and chronic hepatitis, with the latter usually occurring in immunocompromised patients. Modes of transmission range from the classic fecal–oral route or zoonotic route, to relatively recently recognized but increasingly common routes, such as via the transfusion of blood products or organ transplantation. Extrahepatic manifestations, such as neurological, kidney and hematological abnormalities, have been documented in some limited cases, typically in patients with immune suppression. HEV has demonstrated extensive genomic diversity and a variety of HEV strains have been identified worldwide from human populations as well as growing numbers of animal species. The genetic variability and constant evolution of HEV contribute to its physiopathogenesis and adaptation to new hosts. This review describes the recent classification of the Hepeviridae family, global genotype distribution, clinical significance of HEV genotype and genomic variability and evolution of HEV.

Removal of Enteric Pathogens from Real Wastewater Using Single and Catalytic Ozonation

Water scarcity is one of the main problems of this century. Water reclamation appears as an alternative due to the reuse of treated wastewater. Therefore, effluents treatment technologies (activated sludge, rotary biological discs, percolating beds) must be improved since they are not able to remove emerging contaminants such as enteric pathogens (bacteria and virus). These pollutants are difficult to remove from the wastewater and lead to adverse consequences to human health. Advanced oxidation processes, such as single and catalytic ozonation, appear as suitable complements to conventional processes. Catalytic ozonation was carried out using a low-cost material, a volcanic rock. Single and catalytic ozonation were capable of promoting total Escherichia coli removal from municipal wastewater after 90 min of contact. The presence of volcanic rock increases disinfection efficiency since E. coli regrowth was not observed. The identified viruses (Norovirus genotype I and II and JC virus) were completely removed using catalytic ozonation, whereas single ozonation was not able to eliminate JC virus even after 150 min of treatment. The higher performance of the catalytic process can be explained by the formation of hydroxyl radicals, proving that disinfection occurs in the liquid bulk and not due to adsorption at the volcanic rock.

Short communication: detection and molecular characterization of hepatitis E virus in domestic animals of São Tomé and Príncipe

As in most of the African continent, the status of hepatitis E virus (HEV) infection in domestic animals in São Tomé and Príncipe, an archipelago off the western equatorial coast of Central Africa, is also completely unknown. In the present study, we investigated the presence of HEV among domestic animals in São Tomé and Príncipe. A total of 93 stool samples from different animal species (goat, cow, pig, chicken, duck, and monkey) were tested for HEV RNA using two real-time RT-PCR assays, followed by a nested RT-PCR assay for sequencing and phylogenetic analysis. A total of six samples (1 cow stool and 5 pig stools) were found to be positive for HEV RNA of which one pig stool was positive by broad spectrum nested RT-PCR. Phylogenetic analysis showed that the retrieved sequence clustered within HEV subgenotype 3f, similar to zoonotic strains of European countries and posing interesting questions on past introduction of European HEV into São Tomé and Príncipe archipelago. This is the first report describing the presence and molecular characterization of HEV in São Tomé and Príncipe.

Hepatitis E Virus Genotype 1 Cases Imported to Portugal from India, 2016

Hepatitis E in industrialized countries is mainly associated with genotype 3 hepatitis E virus (HEV) and normally causes a sporadic self-limiting disease in immunocompetent individuals. Unlike genotype 3, genotypes 1 and 2 circulate in developing countries, produce severe disease and occur in the epidemic form. Hepatitis E occurring in travellers returning from endemic areas in developing countries is not a novel epidemiological occurrence, however the vast majority of cases remain to be genetically studied. The present study describes two cases of severe acute hepatitis E that required hospitalization for 6 and 9 days in two individuals of Indian nationality that had recently migrated to Portugal to work. The retrieved HEV sequences both belonged to genotype 1 and had a high degree of nucleotide sequence identity, clustering with strains isolated in India and Nepal, in 2013 and 2014. Confirmed HEV genotypes of increased pathogenicity like genotype 1 are being introduced into otherwise naïve populations of industrialized countries such as European countries with consequences difficult to predict. As far as we know the present study is the first in Portugal to describe and genetically characterize imported cases of hepatitis E infection caused by HEV genotype 1.

Acute hepatitis E in India appears to be caused exclusively by genotype 1 hepatitis E virus

BACKGROUND

Hepatitis E is caused by infection with hepatitis E virus (HEV), which has four well-known genotypes. Genotypes 1 and 2 HEV have been reported from human cases in areas where the disease is highly endemic. By contrast, genotypes 3 and 4 HEV, which primarily infect several animal species worldwide, have been reported mainly from sporadic human cases in non-endemic areas such as Japan and high-income countries of Europe and North America. To determine whether genotype 3/4 HEV cause sporadic disease in India, a disease-endemic area, we determined HEV genotype in a group of patients with such disease.

METHODS

A part of the HEV open reading frame (ORF) 1 was amplified and sequenced from sera of 74 patients with sporadic acute viral hepatitis E from four cities in India. The sequences were compared with prototype sequences for various HEV genotypes and subgenotypes and analyzed using phylogenetic tools to determine the genotype of the isolates. For 12 specimens, a part of HEV ORF2 was also similarly analyzed.

RESULTS

Partial ORF1 sequences of all the 74 isolates belonged to genotype 1 HEV, with 88.2% to 100% nucleotide identity with the prototype genotype 1 isolates. Partial ORF2 sequences for all the 12 isolates also belonged to genotype 1 HEV. On phylogenetic analysis, 71 isolates clustered with prototype genotype 1a HEV; the remaining three isolates were located between subgenotypes 1a and 1c but were closer to the former.

CONCLUSION

Human sporadic acute hepatitis E in India is caused almost exclusively by genotype 1 HEV.

Hepatitis E Virus in Industrialized Countries: The Silent Threat

Hepatitis E virus (HEV) is the main cause of acute viral hepatitis worldwide. Its presence in developing countries has been documented for decades. Developed countries were supposed to be virus-free and initially only imported cases were detected in those areas. However, sporadic and autochthonous cases of HEV infection have been identified and studies reveal that the virus is worldwide spread. Chronic hepatitis and multiple extrahepatic manifestations have also been associated with HEV. We review the data from European countries, where human, animal, and environmental data have been collected since the 90s. In Europe, autochthonous HEV strains were first detected in the late 90s and early 2000s. Since then, serological data have shown that the virus infects quite frequently the European population and that some species, such as pigs, wild boars, and deer, are reservoirs. HEV strains can be isolated from environmental samples and reach the food chain, as shown by the detection of the virus in mussels and in contaminated pork products as sausages or meat. All these data highlight the need of studies directed to control the sources of HEV to protect immunocompromised individuals that seem the weakest link of the HEV epidemiology in industrialized regions.

Host immune status and response to hepatitis E virus infection

Hepatitis E virus (HEV), identified over 30 years ago, remains a serious threat to life, health, and productivity in developing countries where access to clean water is limited. Recognition that HEV also circulates as a zoonotic and food-borne pathogen in developed countries is more recent. Even without treatment, most cases of HEV-related acute viral hepatitis (with or without jaundice) resolve within 1 to 2 months. However, HEV sometimes leads to acute liver failure, chronic infection, or extrahepatic symptoms. The mechanisms of pathogenesis appear to be substantially immune mediated. This review covers the epidemiology of HEV infection worldwide, the humoral and cellular immune responses to HEV, and the persistence and protection of antibodies produced in response to both natural infection and vaccines. We focus on the contributions of altered immune states (associated with pregnancy, human immunodeficiency virus [HIV], and immunosuppressive agents used in cancer and transplant medicine) to the elevated risks of chronic infection (in immunosuppressed/immunocompromised patients) and acute liver failure and mortality (among pregnant women). We conclude by discussing outstanding questions about the immune response to HEV and interactions with hormones and comorbid conditions. These questions take on heightened importance now that a vaccine is available.

Emergence of autochthonous infections with hepatitis E virus of genotype 4 in Europe

In Europe, autochthonous hepatitis E is caused by genotype 3 hepatitis E virus (HEV) in almost all cases. A total of 15 infections with genotype 4 HEV were diagnosed in France from May 2009 to April 2012, and all but one of the HEV-4 strains implicated in these infections were genetically related and highly similar to HEV-4 sequences isolated from swine in Belgium. In addition, 5 autochthonous HEV-4 infections have been described in the region of Lazio, Italy, during March and April 2011, and these HEV sequences were 100% identical to one another but showed relatively low similarity (74-85%) to HEV-4 RNA samples collected in France. We report 6 additional HEV-4 infections that were diagnosed from May to July 2012 which represented 50% of the HEV infections diagnosed during this period in our clinical microbiology laboratory. Five of these HEV-4 strains were associated with autochthonous infections and were clustered together and with the majority of HEV-4 previously described in France, whereas the sixth strain was genetically divergent. Taken together with reports from other teams, these observations indicate that autochthonous infections with HEV-4 are emerging in Europe and have been transmitted by at least two distinct sources.

Autochthonous infections with hepatitis E virus genotype 4, France

During January-March 2011, diagnoses of hepatitis E virus (HEV) infection increased in Marseille University hospitals in southeastern France. HEV genotype 4, which is described almost exclusively in Asia, was recovered from 2 persons who ate uncooked pork liver sausage. Genetic sequences were 96.7% identical to those recently described in swine in Europe.

Circulation of genotype 4 hepatitis E virus in Europe: first autochthonous hepatitis E infection in France

BACKGROUND

Human HEV infections reported in Europe without previous travel to endemic regions are linked to exposure to genotype 3 Hepatitis E virus (HEV).Genotype 3 is widely distributed through human cases and zoonotic reservoir. The geographical distribution of genotype 4 is limited to Asian countries.

OBJECTIVES

The first human case of autochthonous genotype 4 hepatitis E infection was reported in France.

STUDY DESIGN

The HEV infection was described in an immunosuppressed patient, presenting an acute myeloblastic leukemia. Investigation of the case was performed on detection of HEV markers in the patient and in the environment.

RESULTS

Hepatitis E infection was diagnosed on the basis of HEV RNA viremia, and detection of anti-HEV IgM. The prognostic of leukemia was favorable and HEV was cleared without relapsing. HEV isolate was classified into genotype 4.

CONCLUSIONS

The recent characterization of genotype 4 HEV through swine surveillance in Europe and the description of the first human case in France open interesting questions about the circulation of this genotype: health risks in human population, transmission patterns, and zoonotic reservoir.

Hepatitis E virus infections in swine and swine handlers in Vellore, Southern India

Hepatitis E virus (HEV) in industrialized countries is zoonotically transmitted, and swine act as a major reservoir of HEV. Serum samples from 102 swine and plasma from 34 swine handlers in Vellore, India were tested by using a reverse transcription-polymerase chain reaction to detect and genotype HEV. We measured levels of IgG against HEV in swine handlers and in age and geographically matched controls from rural and urban populations in Vellore. HEV was amplified from two pigs and both viruses belonged to genotype 4. No HEV RNA was amplified from any swine handler, but 94.1% of swine handlers were positive for antibodies against HEV, a seroprevalence rate significantly higher than in rural and urban controls. The HEV genotype circulating in swine in India is different from that of humans, but the higher antibody levels in swine handlers support the possibility that zoonotic infections may occur.

The molecular epidemiology of hepatitis E virus infection

Molecular characterization of various hepatitis E virus (HEV) strains circulating among humans and animals (particularly swine, deer and boars) in different countries has revealed substantial genetic heterogeneity. The distinctive four-genotype distribution worldwide of mammalian HEV and varying degrees of genetic relatedness among local strains suggest a long and complex evolution of HEV in different geographic regions. The population expansion likely experienced by mammalian HEV in the second half of the 20th century is consistent with an extensive genetic divergence of HEV strains and high prevalence of HEV infections in many parts of the world, including developed countries. The rate and mechanisms of human-to-human transmission and zoonotic transmission to humans vary geographically, thus contributing to the complexity of HEV molecular evolution.

Prior infection of pigs with a genotype 3 swine hepatitis E virus (HEV) protects against subsequent challenges with homologous and heterologous genotypes 3 and 4 human HEV

Hepatitis E virus (HEV) is an important human pathogen. At least four recognized and two putative genotypes of mammalian HEV have been reported: genotypes 1 and 2 are restricted to humans whereas genotypes 3 and 4 are zoonotic. The current experimental vaccines are all based on a single strain of HEV, even though multiple genotypes of HEV are co-circulating in some countries and thus an individual may be exposed to more than one genotype. Genotypes 3 and 4 swine HEV is widespread in pigs and known to infect humans. Therefore, it is important to know if prior infection with a genotype 3 swine HEV will confer protective immunity against subsequent exposure to genotypes 3 and 4 human and swine HEV. In this study, specific-pathogen-free pigs were divided into 4 groups of 6 each. Pigs in the three treatment groups were each inoculated with a genotype 3 swine HEV, and 12 weeks later, challenged with the same genotype 3 swine HEV, a genotype 3 human HEV, and a genotype 4 human HEV, respectively. The control group was inoculated and challenged with PBS buffer. Weekly sera from all pigs were tested for HEV RNA and IgG anti-HEV, and weekly fecal samples were also tested for HEV RNA. The pigs inoculated with swine HEV became infected as evidenced by fecal virus shedding and viremia, and the majority of pigs also developed IgG anti-HEV prior to challenge at 12 weeks post-inoculation. After challenge, viremia was not detected and only two pigs challenged with swine HEV had 1-week fecal virus shedding, suggesting that prior infection with a genotype 3 swine HEV prevented pigs from developing viremia and fecal virus shedding after challenges with homologous and heterologous genotypes 3 and 4 HEV. The results from this study have important implications for future development of an effective HEV vaccine.

Hepatitis E: Historical, contemporary and future perspectives

Hepatitis E was suspected for the first time in 1980 during a waterborne epidemic of acute hepatitis in Kashmir, India. In the 30 years since then, a small virus with single-stranded RNA genome has been identified as the cause of this disease and named as hepatitis E virus (HEV). The virus has four genotypes; of these, genotypes 1 and 2 are known to infect only humans, whereas genotypes 3 and 4 primarily infect other mammals, particularly pigs, but occasionally cause human disease. In highly-endemic areas, the disease occurs in epidemic and sporadic forms, caused mainly by infection with genotype 1 or 2 virus, acquired through the fecal-oral route, usually through contaminated water supplies. The disease is characterized by particularly severe course and high mortality among pregnant women. In persons with pre-existing chronic liver disease, HEV superinfection can present as acute-on-chronic liver disease. In low-endemic regions, sporadic cases of locally-acquired HEV infection are reported; these are caused mainly by genotype 3 or 4 HEV acquired possibly through zoonotic transmission from pigs, wild boars or deer. In these areas, chronic infection with genotype 3 HEV, which may progress to liver cirrhosis, has been reported among immunosuppressed persons. Two subunit vaccines containing recombinant truncated capsid proteins of HEV have been shown to be highly effective in preventing the disease; however, these are not yet commercially available. These vaccines should be of particular use in groups that are at high risk of HEV infection and/or of poor outcome.