Immunological alterations in pregnant women with acute hepatitis E

Hepatitis E virus: from innate sensing to adaptive immune responses

Hepatitis E virus (HEV) infections are a major cause of acute viral hepatitis in humans worldwide. In immunocompetent individuals, the majority of HEV infections remain asymptomatic and lead to spontaneous clearance of the virus, and only a minority of individuals with infection (5-16%) experience symptoms of acute viral hepatitis. However, HEV infections can cause up to 30% mortality in pregnant women, become chronic in immunocompromised patients and cause extrahepatic manifestations. A growing body of evidence suggests that the host immune response to infection with different HEV genotypes is a critical determinant of distinct HEV infection outcomes. In this Review, we summarize key components of the innate and adaptive immune responses to HEV, including the underlying immunological mechanisms of HEV associated with acute and chronic liver failure and interactions between T cell and B cell responses. In addition, we discuss the current status of vaccines against HEV and raise outstanding questions regarding the immune responses induced by HEV and treatment of the disease, highlighting areas for future investigation.

Fetal Loss in Pregnant Rabbits Infected with Genotype 3 Hepatitis E Virus Is Associated with Altered Inflammatory Responses, Enhanced Virus Replication, and Extrahepatic Virus Dissemination with Positive Correlations with Increased Estradiol Level

Hepatitis E virus (HEV) causes adverse clinical outcomes in pregnant women, but the underlying mechanisms remain poorly understood. To delineate the mechanisms of pregnancy-associated adverse effects during HEV infection, we utilized a genotype 3 HEV from rabbit (HEV-3ra) and its cognate host (rabbits) to systematically investigate the clinical consequences, viral replication dynamics, and host immune and hormonal responses of HEV infection during pregnancy. We found a significant fetal loss of 23% in HEV-infected pregnant rabbits, indicating an early-stage miscarriage. HEV infection in pregnant rabbits was characterized by higher viral loads in feces, intestinal contents, liver, and spleen tissues, as well as a longer and earlier onset of viremia than in infected nonpregnant rabbits. HEV infection altered the pattern of cytokine gene expressions in the liver of pregnant rabbits and caused a transient increase of serum interferon gamma (IFN-γ) shortly after a notable increase in viral replication, which may contribute to early fetal loss. Histological lesions in the spleen were more pronounced in infected pregnant rabbits, although moderate liver lesions were seen in both infected pregnant and nonpregnant rabbits. Total bilirubin was elevated in infected pregnant rabbits. The serum levels of estradiol (E2) in HEV-infected pregnant rabbits were significantly higher than those in mock-infected pregnant rabbits at 14 days postinoculation (dpi) and correlated positively with higher viral loads in feces, liver, and spleen tissues at 28 dpi, suggesting that it may play a role in extrahepatic virus dissemination. The results have important implications for understanding the severe diseases associated with HEV infection during pregnancy. IMPORTANCE HEV causes adverse pregnancy outcomes, with a mortality rate of >30% in pregnant women, but the underlying mechanisms are poorly understood. In this study, we utilized HEV-3ra and its cognate host (pregnant rabbit) to delineate the potential underlying mechanisms of pregnancy-associated adverse outcomes during HEV infection. We found that infected pregnant rabbits had a fetal loss of 23%, which coincided with enhanced viral replication and an elevated systemic IFN-γ response, followed by longer viremia duration and extrahepatic viral dissemination. Estradiol levels were increased in infected pregnant rabbits and correlated positively with higher fecal viral shedding and higher viral loads in liver and spleen tissues. Infected pregnant rabbits had more pronounced splenic lesions, higher serum total bilirubin, and an altered cytokine gene expression profile in the liver. The results will contribute to our understanding of the mechanisms of HEV-associated adverse pregnancy outcomes.

Clinical Manifestations of Hepatitis E

The clinical manifestations of hepatitis E are similar to those of other types of viral hepatitis. While acute hepatitis E is usually self-limited, pregnant women and chronic liver disease patients suffering from acute hepatitis E usually present with severe clinical manifestations that may develop into fulminant hepatic failure. Chronic HEV infection is typically seen in organ transplant patients; most HEV cases are asymptomatic and rarely display jaundice, fatigue, abdominal pain, fever, fatigue, or ascites. The clinical manifestations of HEV infection in neonates are diverse and have varied clinical signs, biochemistry, and virus-biomarkers. Lastly, the extrahepatic manifestations and complications of hepatitis E are in need of further study.

Viral hepatitis in pregnancy

Viral hepatitis is caused by a heterogenous group of viral agents representing a wide range of phylogenetic groups. Many viruses can involve the liver and cause liver injury but only a subset are delineated as 'hepatitis viruses' based upon their primary site of replication and tropism for hepatocytes which make up the bulk of the liver cell population. Since their discovery, beginning with the agent that caused serum hepatitis in the 1960s, the alphabetic designations have been utilized. To date, we have five hepatitis viruses, A through E, though it is postulated that others may exist. This chapter will focus on those viruses. Note that hepatitis D is included as a subset of hepatitis B, as it cannot exist without concurrent hepatitis B infection. Pregnancy has the potential to affect all aspects of these viral agents due to the unique immunologic and physiologic changes that occur during and after the gestational period. In this review, we will discuss the most common viral hepatitis and their effects during pregnancy.

Epidemiology of liver failure in Asia-Pacific region

The global burden of deaths caused by liver failure is substantial. The Asia-Pacific region is home to more than half of the global population and accounted for 62.6% of global deaths because of liver diseases in 2015. The aetiology of liver failure varies in different countries at different times. Viruses (Hepatitis A, B and E), drugs (herbs and anti-tuberculous drugs), toxins (alcohol use) and autoimmune flares are mainly responsible of majority of liver failure in individuals with normal liver (acute liver failure; ALF); else these may precipitate liver failure in those with chronic liver disease (acute-on-chronic liver failure; ACLF). Concomitant increases in alcohol misuse and metabolic syndrome in recent years are concerning. Ongoing efforts to address liver failure-related morbidity and mortality require accurate contemporary estimates of epidemiology and outcomes. In light of the ever-changing nature of liver disease epidemiology, accurate estimates for the burden of liver failure across the countries are vital for setting clinical, research and policy priorities. In this review, we aimed to describe the current as well as changing epidemiological trends of common liver failure syndromes, ALF and ACLF in the Asia-Pacific region.

Distribution and Pathogenicity of Two Cutthroat Trout Virus (CTV) Genotypes in Canada

The sole member of the Piscihepevirus genus (family Hepeviridae) is cutthroat trout virus (CTV) but recent metatranscriptomic studies have identified numerous fish hepevirus sequences including CTV-2. In the current study, viruses with sequences resembling both CTV and CTV-2 were isolated from salmonids in eastern and western Canada. Phylogenetic analysis of eight full genomes delineated the Canadian CTV isolates into two genotypes (CTV-1 and CTV-2) within the Piscihepevirus genus. Hepevirus genomes typically have three open reading frames but an ORF3 counterpart was not predicted in the Canadian CTV isolates. In vitro replication of a CTV-2 isolate produced cytopathic effects in the CHSE-214 cell line with similar amplification efficiency as CTV. Likewise, the morphology of the CTV-2 isolate resembled CTV, yet viral replication caused dilation of the endoplasmic reticulum lumen which was not previously observed. Controlled laboratory studies exposing sockeye (Oncorhynchus nerka), pink (O. gorbuscha), and chinook salmon (O. tshawytscha) to CTV-2 resulted in persistent infections without disease and mortality. Infected Atlantic salmon (Salmo salar) and chinook salmon served as hosts and potential reservoirs of CTV-2. The data presented herein provides the first in vitro and in vivo characterization of CTV-2 and reveals greater diversity of piscihepeviruses extending the known host range and geographic distribution of CTV viruses.

Hepatitis E and Pregnancy: An Unholy Alliance Unmasked from Kashmir, India

The adverse relationship between viral hepatitis and pregnancy in developing countries had been interpreted as a reflection of retrospectively biased hospital-based data collection by the West. However, the discovery of hepatitis E virus (HEV) as the etiological agent of an epidemic of non-A, non-B hepatitis in Kashmir, and the documenting of the increased incidence and severity of hepatitis E in pregnancy via a house-to-house survey, unmasked this unholy alliance. In the Hepeviridae family, HEV-genotype (gt)1 from genus Orthohepevirus A has a unique open reading frame (ORF)4-encoded protein which enhances viral polymerase activity and viral replication. The epidemics caused by HEV-gt1, but not any other Orthohepevirus A genotype, show an adverse relationship with pregnancy in humans. The pathogenesis of the association is complex and at present not well understood. Possibly multiple factors play a role in causing severe liver disease in the pregnant women including infection and damage to the maternal-fetal interface by HEV-gt1; vertical transmission of HEV to fetus causing severe fetal/neonatal hepatitis; and combined viral and hormone related immune dysfunction of diverse nature in the pregnant women, promoting viral replication. Management is multidisciplinary and needs a close watch for the development and management of acute liver failure. (ALF). Preliminary data suggest beneficial maternal outcomes by early termination of pregnancy in patients with lower grades of encephalopathy.

Advances in Hepatitis E Virus Biology and Pathogenesis

Hepatitis E virus (HEV) is one of the causative agents for liver inflammation across the world. HEV is a positive-sense single-stranded RNA virus. Human HEV strains mainly belong to four major genotypes in the genus Orthohepevirus A, family Hepeviridae. Among the four genotypes, genotype 1 and 2 are obligate human pathogens, and genotype 3 and 4 cause zoonotic infections. HEV infection with genotype 1 and 2 mainly presents as acute and self-limiting hepatitis in young adults. However, HEV infection of pregnant women with genotype 1 strains can be exacerbated to fulminant hepatitis, resulting in a high rate of case fatality. As pregnant women maintain the balance of maternal-fetal tolerance and effective immunity against invading pathogens, HEV infection with genotype 1 might dysregulate the balance and cause the adverse outcome. Furthermore, HEV infection with genotype 3 can be chronic in immunocompromised patients, with rapid progression, which has been a challenge since it was reported years ago. The virus has a complex interaction with the host cells in downregulating antiviral factors and recruiting elements to generate a conducive environment of replication. The virus-cell interactions at an early stage might determine the consequence of the infection. In this review, advances in HEV virology, viral life cycle, viral interference with the immune response, and the pathogenesis in pregnant women are discussed, and perspectives on these aspects are presented.

IgG antibody response demonstrates inverse correlation with viral load in Bangladeshi women with acute hepatitis E virus genotype 1 infection

OBJECTIVES

To determine IgG immune responses and hepatitis E virus (HEV) viral load, and to explore the associations with pregnancy.

METHODS

A total of 121 HEV-infected women (57 pregnant, 64 non-pregnant) were analysed. Quantitative reverse transcription PCR (RT-qPCR) was done for 78 HEV IgM-positive patients to determine viral load, and Sanger sequencing was performed for 62 HEV-RNA-positive patients to confirm genotyping. ELISA was conducted to determine HEV antibody and avidity indices.

RESULTS

The HEV genotype was identified as variant 1. Significant negative correlations were observed between log HEV copy number and log hepatitis E virus IgG antibody index in the late acute phase of jaundice for both pregnant women (r = -0.7971, p = 0.0002) and non-pregnant women (r = -0.9117, p = 0.0002). Pregnant women had significantly higher serum log viral copy numbers and lower IgG antibody indices than non-pregnant women in the late acute phase of HEV-induced jaundice (p = 0.0196 and p = 0.0303, respectively). Moreover, pregnant women with acute HEV hepatitis had higher cross-reactive IgG antibodies compared to the non-pregnant women (p = 0.0017). Five patients with HEV hepatitis died, of whom four were pregnant.

CONCLUSIONS

Pregnancy might be associated with higher viral loads and a lower IgG response in the HEV-induced late acute phase of jaundice.

Altered faecal microbiota on the expression of Th cells responses in the exacerbation of patients with hepatitis E infection

Fulminant hepatitis E may lead to acute liver failure (ALF). Perturbations of intestinal microbiota are related to severe liver disease. To study the correlations between faecal microbiota and the occurrence and exacerbation of hepatitis E virus (HEV) infection, we characterized 24 faecal samples from 12 patients with acute hepatitis E (AHE) and 12 patients with HEV-ALF using high-throughput sequencing. We found both the alpha and beta diversity indices showed no significant differences between the AHE and HEV-ALF groups. Several predominant taxa were significantly different between the AHE and HEV-ALF groups. Most notably, the HEV-ALF group had increased levels of Gammaproteobacteria, Proteobacteria, Xanthomonadceae and Stenotrophomonas, but reduced levels of Firmicutes, Streptococcus, Subdoligranulum and Lactobacillus, compared with the AHE group. The levels of Lactobacillaceae and Gammaproteobacteria could be used to distinguish patients with HEV-ALF from those with AHE. In addition, the level of Th lymphocytes was significantly lower in the HEV-ALF group than in the AHE group. The relative abundances of Lactobacillaceae and Gammaproteobacteria were positively correlated with Th lymphocytes, serum international normalized ratio (INR) and hepatic encephalopathy severity. Moreover, surviving patients had higher levels of Lactobacillus mucosae than deceased patients. Our study demonstrated that the presence of altered faecal microbiota is associated with exacerbation of HEV infection; this finding may be useful for exploring the interactions among faecal microbiota, immune responses, mechanisms of infection and progression in patients with HEV, as well as for the development of novel diagnostic and therapeutic strategies.

Vertical transmission of hepatitis E virus in pregnant rhesus macaques

Hepatitis E virus (HEV) is the major pathogen of viral hepatitis. HEV causes high mortality in pregnant women. Its infection during pregnancy usually leads to fulminant hepatic failure, spontaneous abortions, premature delivery, or stillbirth. Vertical transmission of HEV has been reported, but the pathogenesis during pregnancy remains largely elusive. Pregnant rhesus macaques were infected with HEV to explore the pathogenesis of genotype 4 HEV infection during pregnancy. Active HEV infections were established with shedding viruses in the feces and blood, and elevated liver enzymes. Notably, higher viral titers and longer durations of HEV infection were found in HEV-infected pregnant rhesus macaques than in non-pregnant macaques. Premature delivery and fetal death occurred in one of the HEV-infected pregnant rhesus macaques. HEV RNA was detected in the liver, spleen, kidneys, and intestines of the dead fetus. This result strongly indicated vertical HEV transmission from mother to fetus. Maternal-transferred antibodies were observed in one of the babies with poor protection. The expressions of interferon-stimulated genes (ISGs) related to HEV infection were completely different between pregnant and non-pregnant rhesus macaques. During pregnancy, impaired innate immune responses, reduced progesterone levels, and shifts in immune states may aggravate HEV infection and result in adverse pregnancy outcomes.

Indian National Association for the Study of the Liver Consensus Statement on Acute Liver Failure (Part 1): Epidemiology, Pathogenesis, Presentation and Prognosis

Acute liver failure (ALF) is an infrequent, unpredictable, potentially fatal complication of acute liver injury (ALI) consequent to varied etiologies. Etiologies of ALF as reported in the literature have regional differences, which affects the clinical presentation and natural course. In this part of the consensus article designed to reflect the clinical practices in India, disease burden, epidemiology, clinical presentation, monitoring, and prognostication have been discussed. In India, viral hepatitis is the most frequent cause of ALF, with drug-induced hepatitis due to antituberculosis drugs being the second most frequent cause. The clinical presentation of ALF is characterized by jaundice, coagulopathy, and encephalopathy. It is important to differentiate ALF from other causes of liver failure, including acute on chronic liver failure, subacute liver failure, as well as certain tropical infections which can mimic this presentation. The disease often has a fulminant clinical course with high short-term mortality. Death is usually attributable to cerebral complications, infections, and resultant multiorgan failure. Timely liver transplantation (LT) can change the outcome, and hence, it is vital to provide intensive care to patients until LT can be arranged. It is equally important to assess prognosis to select patients who are suitable for LT. Several prognostic scores have been proposed, and their comparisons show that indigenously developed dynamic scores have an edge over scores described from the Western world. Management of ALF will be described in part 2 of this document.

Hepatitis E virus infection during pregnancy

BACKGROUND

Hepatitis E virus (HEV) generally causes self-limiting viral hepatitis. However, in pregnant women, HEV infection can be severe and has been associated with up to 30% mortality in the third trimester. Additionally, HEV infection in pregnancy is also associated with high rates of preterm labor and vertical transmission.

MAIN BODY

HEV is now recognized as a global health problem in both developing and industrialized countries. HEV can be transmitted via the fecal-oral route, zoonotic route, and blood transfusion route. An altered immune status, hormonal levels, and viral factors may be related to the severity of the disease. Currently, no established treatment is available for HEV in pregnant women. A Chinese vaccine has been demonstrated to be protective against HEV in the general population and seems to be safe in pregnancy; however, its safety and efficacy in a large population of pregnant women remain to be determined.

CONCLUSION

This review summarizes the current knowledge about HEV infection during pregnancy and focuses on the epidemiology, clinical manifestations, mechanisms underlying severe liver injury, and management and prevention of HEV infection during pregnancy. Considering that HEV infection during pregnancy may result in poor outcomes, screening for and monitoring HEV infection early in pregnancy should be taken into account. In addition, a better understanding of the pathogenesis will help to develop potential treatment strategies targeting HEV infection in pregnancy.

Clinical Manifestations, Pathogenesis and Treatment of Hepatitis E Virus Infections

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis throughout the world. Most infections are acute but they can become chronic in immunocompromised patients, such as solid organ transplant patients, patients with hematologic malignancy undergoing chemotherapy and those with a human immunodeficiency virus (HIV) infection. Extra-hepatic manifestations, especially neurological and renal diseases, have also been described. To date, four main genotypes of HEV (HEV1-4) were described. HEV1 and HEV2 only infect humans, while HEV3 and HEV4 can infect both humans and animals, like pigs, wild boar, deer and rabbits. The real epidemiology of HEV has been underestimated because most infections are asymptomatic. This review focuses on the recent advances in our understanding of the pathophysiology of acute HEV infections, including severe hepatitis in patients with pre-existing liver disease and pregnant women. It also examines the mechanisms leading to chronic infection in immunocompromised patients and extra-hepatic manifestations. Acute infections are usually self-limiting and do not require antiviral treatment. Conversely, a chronic HEV infection can be cleared by decreasing the dose of immunosuppressive drugs or by treating with ribavirin for 3 months. Nevertheless, new drugs are needed for those cases in which ribavirin treatment fails.

CD8+ lymphocytes but not B lymphocytes are required for protection against chronic hepatitis E virus infection in chickens

Hepatitis E is an important global disease, causing outbreaks of acute hepatitis in many developing countries and sporadic cases in industrialized countries. Hepatitis E virus (HEV) infection typically causes self-limiting acute hepatitis but can also progress to chronic disease in immunocompromised individuals. The immune response necessary for the prevention of chronic infection is T cell-dependent; however, the arm of cellular immunity responsible for this protection is not currently known. To investigate the contribution of humoral immunity in control of HEV infection and prevention of chronicity, we experimentally infected 20 wild-type (WT) and 18 immunoglobulin knockout (JH-KO) chickens with a chicken strain of HEV (avian HEV). Four weeks postinfection (wpi) with avian HEV, JH-KO chickens were unable to elicit anti-HEV antibody but had statistically significantly lower liver lesion scores than the WT chickens. At 16 wpi, viral RNA in fecal material and liver, and severe liver lesions were undetectable in both groups. To determine the role of cytotoxic lymphocytes in the prevention of chronicity, we infected 20 WT and 20 cyclosporine and CD8⁺ antibody-treated chickens with the same strain of avian HEV. The CD8 ⁺ lymphocyte-depleted, HEV-infected chickens had higher incidences of prolonged fecal viral shedding and statistically significantly higher liver lesion scores than the untreated, HEV-infected birds at 16 wpi. The results indicate that CD8 ⁺ lymphocytes are required for viral clearance and reduction of liver lesions in HEV infection while antibodies are not necessary for viral clearance but may contribute to the development of liver lesions in acute HEV infection.

Natural History, Clinical Manifestations, and Pathogenesis of Hepatitis E Virus Genotype 1 and 2 Infections

Infection with genotype 1 or 2 hepatitis E virus (HEV) results primarily from human-to-human transmission through the fecal-oral route in low-resource countries. It presents primarily as "acute viral hepatitis" syndrome, usually a self-limiting illness. A few cases progress to acute liver failure, a serious illness with high fatality. Clinical disease is infrequent among children. Infection during pregnancy is associated with a higher risk of symptomatic disease, severe liver injury, and mortality. Severe disease is also encountered in persons with preexisting chronic liver disease. Some cases have associated extrahepatic features, particularly acute pancreatitis and neurological manifestations. Chronic infection appears to be extremely infrequent with these HEV genotypes. The exact pathogenesis of liver injury remains unknown, although the host immune response appears to be important for viral clearance as well as for induction of liver injury. Hormonal and immune factors appear to be responsible for the severe disease during pregnancy.

The Interplay between Host Innate Immunity and Hepatitis E Virus

Hepatitis E virus (HEV) infection represents an emerging global health issue, whereas the clinical outcomes vary dramatically among different populations. The host innate immune system provides a first-line defense against the infection, but dysregulation may partially contribute to severe pathogenesis. A growing body of evidence has indicated the active response of the host innate immunity to HEV infection both in experimental models and in patients. In turn, HEV has developed sophisticated strategies to counteract the host immune system. In this review, we aim to comprehensively decipher the processes of pathogen recognition, interferon, and inflammatory responses, and the involvement of innate immune cells in HEV infection. We further discuss their implications in understanding the pathogenic mechanisms and developing antiviral therapies.

Epidemiology of Genotype 1 and 2 Hepatitis E Virus Infections

Hepatitis E virus (HEV) genotypes 1 and 2 are responsible for the majority of acute viral hepatitis infections in endemic areas in South Asia and sub-Saharan Africa. In addition to frequent sporadic illnesses throughout the year, these viruses often cause large epidemics in association with monsoon rains in Asia or during humanitarian crises in Africa. Clinical hepatitis commonly involves adults more often than young children, with an overall mortality of ∼1%. However, the mortality among pregnant women is often 30% or higher. HEV infection in pregnant women frequently leads to infant mortality or premature delivery. Hepatitis E is an important, yet largely neglected, global public health problem.

Role of oestrogen and its receptors in HEV-associated feto-maternal outcomes

BACKGROUND

Pregnant women infected with HEV develops adverse pregnancy outcomes like, abortions, intrauterine fetal death, still births, neonatal deaths, preterm delivery and maternal mortality.

AIM

To correlate oestrogen and its receptors ESR1α and ESR2β levels with HEV-associated feto-maternal outcomes.

MATERIAL & METHODS

A total of 142 pregnant women with HEV infection and 142 pregnant controls were included in study from Department of Obstetrics & Gynaecology and Department of Medicine, Maulana Azad Medical College (MAMC) and associated Lok Nayak Hospital (LNH), New Delhi. Three millilitre of blood sample was collected in plain for quantification of oestrogen, and its receptors ESR1α and ESR2β using commercially available third-generation ELISA kits.

RESULTS

The levels of oestrogen, ESR1α and ESR2β were considerably higher in HEV-infected pregnant women (20.11 ± 18.19 ng/mL, 10.58 ± 3.27 ng/mL, 10.42 ± 4.71 ng/mL respectively) than pregnant controls (11.74 ± 6.42 ng/mL, 9.11 ± 1.63 ng/mL, 9.01 ± 1.18 ng/mL respectively)(P < 0.0001). It was found that oestrogen levels were significantly higher in pregnant women infected with HEV who had preterm delivery, low birth weight babies and fetal loss (19.64 ± 17.60 ng/mL, 19.71 ± 17.63 ng/mL, 33.62 ± 23.20 ng/mL respectively) than who had full term delivery, average birth weight babies and live babies (11.71 ± 8.77 ng/mL, 11.99 ± 9.44 ng/mL, 16.58 ± 14.98 ng/mL respectively)(P < 0.05). A significant negative correlation was observed between baby birth weight and oestrogen levels in HEV-infected pregnant women.

CONCLUSION

The high level of oestrogen plays an important role in preterm delivery, low birth weight babies and fetal mortality in pregnant women with HEV infection through placental dysfunction. Moreover, oestrogen level is a significant predictor for preterm delivery and maternal mortality and ESR2β levels is a significant predictor for maternal mortality in pregnant women infected with HEV.

A guide to the management of hepatitis E infection during pregnancy

Hepatitis E virus (HEV) infection has distinct features, depending upon the genotype and geographical area. HEV genotypes 1 and 2 are endemic to various developing countries causing epidemics of acute viral hepatitis with human to human transmission. On the other hand, HEV genotypes 3 and 4 prevalent in developed countries commonly lead to subclinical infection and are transmitted zoonotically. HEV infection typically causes acute self-limiting illness associated with low morbidity and mortality. Infection with HEV genotype 1 or 2 in pregnancy, especially in the third trimester may lead to severe illness and fulminant liver failure. Poor maternal and fetal outcomes have been reported. Areas covered: This review highlights the various aspects of HEV infection in pregnancy including diagnosis, management, and prevention. Expert commentary: Treatment is mainly supportive with diligent monitoring and intensive care. Therapeutic termination of pregnancy cannot be recommended based to the available literature. Early liver transplantation (LT) should be considered in these patients although the indications and timing of LT are still controversial. Prevention of HEV infection or illness by improved sanitation and active/passive immunization needs further research.

Zoonotic Hepatitis E Virus: An Ignored Risk for Public Health

Hepatitis E virus (HEV) is a quasi-enveloped, single-stranded positive-sense RNA virus. HEV belongs to the family Hepeviridae, a family comprised of highly diverse viruses originating from various species. Since confirmation of HEV's zoonosis, HEV-induced hepatitis has been a public health concern both for developing and developed countries. Meanwhile, the demonstration of a broad host range for zoonotic HEV suggests the existence of a variety of transmission routes that could lead to human infection. Moreover, anti-HEV antibody serosurveillance worldwide demonstrates a higher than expected HEV prevalence rate that conflicts with the rarity and sporadic nature of reported acute hepatitis E cases. In recent years, chronic HEV infection, HEV-related acute hepatic failure, and extrahepatic manifestations caused by HEV infection have been frequently reported. These observations suggest a significant underestimation of the number and complexity of transmission routes previously predicted to cause HEV-related disease, with special emphasis on zoonotic HEV as a public health concern. Significant research has revealed details regarding the virology and infectivity of zoonotic HEV in both humans and animals. In this review, the discovery of HEV zoonosis, recent progress in our understanding of the zoonotic HEV host range, and classification of diverse HEV or HEV-like isolates from various hosts are reviewed in a historic context. Ultimately, this review focuses on current understanding of viral pathogenesis and cross-species transmission of zoonotic HEV. Moreover, host factors and viral determinants influencing HEV host tropism are discussed to provide new insights into HEV transmission and prevalence mechanisms.

Impact of maternal nutrition in hepatitis E infection in pregnancy

BACKGROUND AND AIM

The basis of host response in hepatitis E virus (HEV)-related liver disease during pregnancy-is still unclear. The study aims to evaluate anthropometric parameters and biochemical nutritional parameters in hepatitis E infection during pregnancy and correlate it with severity of the disease.

METHODS

A total of consecutive 267 pregnant women with jaundice were recruited. The jaundiced patients were classified as acute viral hepatitis (AVH) or acute liver failure (ALF). The study group included 144 pregnant women with HEV infection and 144 healthy asymptomatic age and gestational age-matched pregnant women as controls. Nutritional factors were evaluated on basis of anthropometric parameters and biochemical factors. Serum prealbumin and folate were assayed by ELISA kit.

RESULTS

All nutritional parameters were significantly lower in pregnant women with HEV infection as compared with healthy pregnant controls. Some of the nutritional parameters significantly lower in ALF pregnant patients compared to AVH pregnant patients in HEV group. Linear regression analysis of the AVH group showed that serum total protein and mid-upper arm circumference (MUAC) were significant predictors for bilirubin, body mass index (BMI) could significantly predict viral load level, and total protein, prealbumin, folate, and tricep skin fold thickness (TSFT) could significantly predict prothrombin time. In ALF group, serum prealbumin could significantly predict bilirubin levels and MUAC could significantly predict prothrombin time.

CONCLUSION

Malnutrition might confer a higher predisposition for HEV infection during pregnancy and is associated with increased severity of disease in terms of occurrence of ALF.

Hepatitis E: prevention and treatment

PURPOSE OF REVIEW

Infection with the hepatitis E virus (HEV) is very common worldwide. The epidemiology, viral genotypes, and transmission routes differ between low-resource countries and economically developed countries. These differences have resulted in the design of diverse prevention and treatment strategies to combat HEV.

RECENT FINDINGS

The population seroprevalence of HEV immunoglobulin G varies between 5 and 50%. However, the diagnosis of acute hepatitis from HEV has not been common in the United States or Western Europe. Chronic progressive HEV infections have been reported among patients who are immunocompromised. Successful treatment of patients with chronic hepatitis from HEV infection with antiviral agents, such as ribavirin or interferon-α, has been reported. Extrahepatic manifestations of HEV infection are common. Large epidemics of hundreds or thousands of cases continue to be reported among populations in Asia and Africa. A subunit peptide HEV vaccine has been found to be highly efficacious in a large clinical trial. However, the vaccine has not been evaluated in populations of pregnant women or other risk groups and is only available in China.

SUMMARY

Although HEV infections are increasingly recognized as a global public health problem, there are few methods for prevention and treatment that are widely available.

Clinical Manifestations of Hepatitis E

The clinical manifestations of hepatitis E are similar to those of other types of viral hepatitis. While acute hepatitis E is usually self-limited, pregnant women and chronic liver disease patients suffering from acute hepatitis E usually present with severe clinical manifestations that may develop into fulminant hepatic failure. Chronic HEV infection is typically only seen in organ transplant patients; most HEV cases are asymptomatic and rarely display jaundice, fatigue, abdominal pain, fever, fatigue, or ascites. The clinical manifestations of HEV infection in neonates are diverse and have varied clinical signs, biochemistry, and virus biomarkers. Lastly, the extrahepatic manifestations and complications of hepatitis E are in need of further study.

Fetomaternal outcomes in pregnant women with hepatitis E infection; still an important fetomaternal killer with an unresolved mystery of increased virulence in pregnancy

Objective:

Hepatitis is a prevalent infection in developing countries. While hepatitis B and C are deepening their roots in the developed world, hepatitis A and E are common in the developing world. The uniqueness of hepatitis is in its transformation from a relatively self-limiting disease in the non-pregnant state, to a highly virulent disease during pregnancy.

Materials and Methods:

This retrospective observational study was conducted in the Department of Obstetrics and Gynecology, King George’s Medical University, Lucknow, for a period of six months from June 2016 to November 2016 [probably during an endemic peak of hepatitis E virus (HEV)] to observe the clinical outcomes in HEV-infected pregnant women.

Results:

A total of 32 anti-HEV immunoglobulin M-positive pregnant women were included, and fetomaternal outcomes were analyzed. Hepatitis E positivity was significantly associated with maternal mortality, intrauterine demise with prematurity, and premature rupture of membranes was the most common fetal complication noted.

Conclusion:

The difference in extent of virulence of infection and variations in maternal morbidity, mortality, and rates of intrauterine demise, signify the presence of some factors that play a role and need to be further studied and evaluated.

Hepatitis E and pregnancy: current state

Hepatitis E virus (HEV) is responsible for more than 50% of acute viral hepatitis cases in endemic countries. Approximately 2 billion individuals live in hepatitis E-endemic areas and, therefore, are at risk of infection. According to World Health Organization, HEV causes about 20.1 million infections and 70 000 deaths every year. In developing countries with poor sanitation, this disease is transmitted through contaminated water and is associated with large outbreaks, affecting hundreds or thousands of people. In developed countries, autochthonous cases of HEV have been increasingly recognized in the past several years. Hepatitis E virus typically causes an acute, self-limiting illness similar to other acute viral hepatitis, such as hepatitis A or B, with about 0.2% to 1% mortality rate in the general population. However, the course of hepatitis E in pregnancy is different than the mild self-constraining infection described in other populations. During pregnancy, HEV infection can take a fulminant course, resulting in fulminant hepatic failure, membrane rupture, spontaneous abortions, and stillbirths. Studies from various developing countries have shown a high incidence of HEV infection in pregnancy with a significant proportion of pregnant women progressing to fulminant hepatitis with a fatality rate of up to 30%. The present review will highlight new aspects of the HEV infection and pregnancy.

The global burden of hepatitis E outbreaks: a systematic review

Hepatitis E virus (HEV) is responsible for repeated water-borne outbreaks since the past century, representing an emerging issue in public health. However, the global burden of HEV outbreak has not been comprehensively described. We performed a systematic review of confirmed HEV outbreaks based on published literatures. HEV outbreaks have mainly been reported from Asian and African countries, and only a few from European and American countries. India represents a country with the highest number of reported HEV outbreaks. HEV genotypes 1 and 2 were responsible for most of the large outbreaks in developing countries. During the outbreaks in developing countries, a significantly higher case fatality rate was observed in pregnant women. In fact, outbreaks have occurred both in open and closed populations. The control measures mainly depend upon improvement of sanitation and hygiene. This study highlights that HEV outbreak is not new, yet it is a continuous global health problem.

Characterization of the Specificity, Functionality, and Durability of Host T-Cell Responses Against the Full-Length Hepatitis E Virus

The interplay between host antiviral immunity and immunopathology during hepatitis E virus (HEV) infection determines important clinical outcomes. We characterized the specificity, functionality, and durability of host T-cell responses against the full-length HEV virus and assessed a novel "Quantiferon" assay for the rapid diagnosis of HEV infection. Eighty-nine volunteers were recruited from Oxford, Truro (UK), and Toulouse (France), including 44 immune-competent patients with acute HEV infection, 18 HEV-exposed immunosuppressed organ-transplant recipients (8 with chronic HEV), and 27 healthy volunteers. A genotype 3a peptide library (616 overlapping peptides spanning open reading frames [ORFs] 1-3) was used in interferon-gamma (IFN-γ) T-cell ELISpot assays. CD4⁺ /CD8⁺ T-cell subsets and polyfunctionality were defined using ICCS and SPICE analysis. Quantification of IFN-γ used whole-blood stimulation with recombinant HEV-capsid protein in the QuantiFERON kit. HEV-specific T-cell responses were detected in 41/44 immune-competent HEV exposed volunteers (median magnitude: 397 spot-forming units/10⁶ peripheral blood mononuclear cells), most frequently targeting ORF2. High-magnitude, polyfunctional CD4 and CD8⁺ T cells were detected during acute disease and maintained to 12 years, but these declined over time, with CD8⁺ responses becoming more monofunctional. Low-level responses were detectable in immunosuppressed patients. Twenty-three novel HEV CD4⁺ and CD8⁺ T-cell targets were mapped predominantly to conserved genomic regions. QuantiFERON testing demonstrated an inverse correlation between IFN-γ production and the time from clinical presentation, providing 100% specificity, and 71% sensitivity (area under the receiver operator characteristic curve of 0.86) for HEV exposure at 0.3 IU/mL.

CONCLUSION

Robust HEV-specific T-cell responses generated during acute disease predominantly target ORF2, but decline in magnitude and polyfunctionality over time. Defining HEV T-cell targets will be important for the investigation of HEV-associated autoimmune disease. (Hepatology 2016;64:1934-1950).

Advances in hepatitis E - I: virology, pathogenesis and diagnosis

INTRODUCTION

Infection with hepatitis E virus (HEV) is the commonest cause of acute hepatitis worldwide. HEV was discovered in 1980s and is known to have small non-enveloped virions with single-stranded RNA genome of positive polarity. In recent years. In recent years, availability of new information has changed our understanding of this virus and the pathogenesis of the related disease.

AREAS COVERED

This article reviews the current knowledge about structure, genomic organization, taxonomy, genetic epidemiology, host specificity and replication of the human HEV and of various closely-related viruses that infect other animals. In addition, the models available for the study of HEV infection, the available information on the pathogenesis of this infection and the techniques available for its diagnosis are also reviewed. Expert commentary: A circulating, enveloped form of the human HEV has been recently recognized. Originally believed to naturally infect only humans and possibly primates, HEV-like viruses are now known to infect several vertebrate animals. Based on this, phylogenetic classification of these viruses has recently been revised. In vitro replicons and infection systems have been developed, which have improved our understanding about the virus and the pathogenesis of infection with it. Recent development of mouse models with chimeric livers that contain human hepatocytes provides another avenue for further advancement of this knowledge.

Hepatitis E Pathogenesis

Although most hepatitis E virus (HEV) infections are asymptomatic, some can be severe, causing fulminant hepatitis and extra-hepatic manifestations, including neurological and kidney injuries. Chronic HEV infections may also occur in immunocompromised patients. This review describes how our understanding of the pathogenesis of HEV infection has progressed in recent years.

Serum Levels of Soluble CD26, A Novel Prognostic Marker for Hepatitis E Infection

Background:

Even without treatment, most acute hepatitis E virus (HEV) infected patients resolve HEV but sometimes the disease leads to acute liver failure, chronic infection, or extrahepatic symptoms. The mechanisms of HEV pathogenesis appear to be substantially immune mediated. However, the immune responses to HEV are not precisely identified.

Objectives:

This study aimed to evaluate the Th1/Th2 ratio by investigating serum soluble markers from Th1 and Th2 cells in acute HEV infected patients.

Patients and Methods:

This case-control study included 35 acute HEV infected patients and 35 age and gender matched anti-HEV negative healthy controls. The serum levels of Interferon (IFN)-γ, IL-4, soluble CD26 (sCD26) and sCD30 were determined by the enzyme-linked immunosorbent assay.

Results:

The results showed a significant difference in IFN-γ and sCD26 (P < 0.0001 and P = 0.001) yet not IL-4 and sCD30 (P = 0.354 and P = 0.159) between acute HEV patients and controls, respectively. There was a positive direct correlation between serum levels of sCD26 and IFN-γ in acute HEV patients (r = 0.64, P = 0.001). In addition, the ratio of sCD26/sCD30 in the acute HEV group was more than two folds higher than in the HEV negative controls.

Conclusions:

Acute HEV infection shows a pattern of Th1-type immune response, and the direct significant positive correlation between the serum level of sCD26 and IFN-γ in acute HEV infected patients, suggests that the trend of sCD26 levels is a valuable marker for predicting hepatic inflammation in hepatitis E.

Prophylaxis against hepatitis E: at risk populations and human vaccines

Hepatitis E is an emerging global disease caused by hepatitis E virus (HEV) infection. While in developing countries the infection was primarily due to poor sanitary conditions through intake of contaminated water or undercooked meats of infected animals, increasing cases of chronic hepatitis E resulting in rapidly progressive liver cirrhosis and end-stage liver disease have been reported in organ transplant patients or in immune compromised patients in developed countries. Fortunately, hepatitis E is now a vaccine preventable disease with a HEV239 based vaccine licensed for human use. Much work is needed to enable its use outside China. This review recounted the development process of the vaccine, outlined the critical quality attributes of the vaccine antigen and, most importantly, listed the populations at risk for HEV infection and the subsequent disease. These at risk populations could benefit the most from the vaccination if the vaccine is widely adopted.

Impaired monocyte-macrophage functions and defective Toll-like receptor signaling in hepatitis E virus-infected pregnant women with acute liver failure

Acute viral hepatitis resulting due to hepatitis E viral infection (AVH-E) is often serious in pregnancy and could result in acute liver failure (ALF). The role of monocytes and macrophages (mono-macs) in the pathogenesis of AVH-E and development of ALF-E in pregnancy is unclear. We investigated the functions of mono-macs in pregnant (P), AVH-E (n = 44), ALF-E (n = 12), healthy controls (HC; n = 20) and compared with nonpregnant (NP) AVH-E (n = 10), ALF-E (n = 5), and HC (n = 10). We also recruited non-hepatitis E virus-related pregnant (P), ALF-NE (n = 5) and non-pregnant (NP), ALF-NE (n = 12) patients with ALF. Mono-macs, dendritic cell (DC) phenotypes, and Toll-like receptor (TLR) expressions were studied by flow cytometry and reverse-transcriptase polymerase chain reaction. Mono-macs functionality was determined by analyzing their phagocytic activity and reactive oxygen species (ROS) generation by using flow cytometry. Frequency of mono-macs and DCs was increased during HEV infection compared to HC (P < 0.001). Macrophages were increased (P < 0.002) in ALF-E(P) compared to ALF-NE(P). The macrophage phagocytic activity and Escherichia coli-induced ROS production was significantly impaired in ALF-E(P) compared to AVH-E(P) (P < 0.001), ALF-E(NP), and ALF-NE(P) patients (P < 0.02). TLR3 and TLR9 expression and downstream MYD88 signalling molecules IRF3 and IRF7 were significantly down-regulated in ALF-E(P) (P < 0.00) compared to AVH-E(P) and ALF-NE(P).

CONCLUSION

Functionality of mono-macs is impaired in pregnant ALF-E patients compared to AVH-E(P). Reduced TLR3 and TLR7 expression and TLR downstream-signaling molecules in pregnant ALF-E patients suggests inadequate triggers for the innate immune responses contributing to development and severity of ALF-E. Studies using TLR agonists to activate mono-macs may be of use and in vitro studies should be undertaken using patient samples.

The Association of Cytokines and Micronutrients with Hepatitis E Virus Infection During Pregnancy and the Postpartum Period in Rural Bangladesh

Hepatitis E virus (HEV) infection is severe during pregnancy, with a pregnant case fatality rate around 30%. In Bangladesh, plasma samples from 1,100 women during the first trimester (TM) and third TM of pregnancy and 3 months postpartum (PP) were tested for anti-HEV IgG. During this time, 40 women developed antibody responses to HEV. These seroconverters are classified as the cases (incidence = 46 infections per 1,000 person-years). All except one seroconversion occurred between the third TM and 3 months PP. The cases and 40 matched non-seroconverters (controls) underwent analysis of a panel of 10 cytokines, 12 vitamins and minerals, and two markers of inflammation. Throughout pregnancy, seroconverting cases displayed higher concentrations of both pro- and anti-inflammatory cytokines compared with the non-seroconverting controls, even prior to infection. In the first TM, seroconverters had lower circulating zinc concentrations (P = 0.03), an increased prevalence of vitamin D deficiency (25-hydroxy vitamin D [25(OH)2D] < 50 nmol/L, P = 0.08), and anemia (hemoglobin < 110 g/L, P = 0.05) compared with controls. There were no differences in C-reactive protein or α-1-acid glycoprotein. Antecedent micronutrient deficiencies may lead to dysregulated cytokine expression and immunologic compromise, increasing the risk of HEV infection, especially during pregnancy. This exploratory analysis reveals potential novel associations that deserve further study.

Cytokine Profiles and Cell Proliferation Responses to Truncated ORF2 Protein in Iranian Patients Recovered from Hepatitis E Infection

Background. The aim of this study was to evaluate hepatitis E virus (HEV) specific cellular immune responses to truncated ORF2 protein in Iranian patients recovered from HEV infection. Information about HEV-specific immune responses could be useful in finding an effective way for development of HEV vaccine. Methods. A truncated form of HEV ORF2 protein containing amino acids 112-608 was used to stimulate peripheral blood mononuclear cells (PBMCs) separated from HEV-recovered and control groups. Finally, the levels of four cytokines, IFN-γ ELISPOT, and cell proliferative responses following stimulation with the truncated ORF2 protein were assessed in the both groups. Results. The truncated ORF2 protein was able to induce IFN-γ ELISPOT and cell proliferation responses and to produce significant amounts of IFN-γ and IL-12 cytokines, but low amounts of IL-10 and IL-4 cytokines in vitro. These responses were significantly higher in the recovered group compared to the control group. These results indicate the antigenic nature of the truncated ORF2 protein and production of T helper type 1 cytokines. Conclusion. The truncated ORF2 protein can effectively induce significant cellular immune responsesand can be introduced as a potential vaccine candidate. However, further studies are required to evaluate this protein in vivo.

Changes in gene expression in liver tissue from patients with fulminant hepatitis E

AIM: To study host gene expression and number of immune cells in liver tissues from patients with fulminant hepatitis E (FH-E).

METHODS: Microarray-based expression profiling was done using Illumina Human WG-6_v3_BeadChip arrays on post-mortem liver tissue from 5 patients with FH-E, and compared with similar tissue from 6 patients with fulminant hepatitis B (FH-B; disease controls) and normal liver tissue from 6 persons. Differential expression was defined as ≥ 2.0-fold change with Benjamini-Hochberg false discovery rate below 0.05 using t-test in liver tissue from FH-B and FH-E, than healthy liver tissue. For some genes that showed differential expression in FH-E, microarray data were validated using quantitative reverse transcription PCR. Differentially expressed gene lists were then subjected to “Gene Ontology” analysis for biological processes, and pathway analysis using BioCarta database on the DAVID server. In addition, tissue sections were stained for CD4⁺, CD8⁺ and CD56⁺ cells using indirect immunohistochemistry; cells staining positive for each of these markers were counted and compared between groups.

RESULTS: Compared to normal livers, those from patients with FH-E and FH-B showed differential expression of 3377 entities (up-regulated 1703, downregulated 1674) and 2572 entities (up 1164, down 1408), respectively. This included 2142 (up 896, down 1246) entities that were common between the two sets; most of these belonged to metabolic, hemostatic and complement pathways, which are active in normal livers. Gene expression data from livers of patients with FH-E but not those of FH-B showed activation of several immune response pathways, particularly those involving cytotoxic T cells. The fold-change values of mRNA for selected genes in livers from FH-E than in normal liver tissue determined using quantitative reverse transcription PCR showed excellent concordance with microarray analysis. At immunohistochemistry, CD8⁺ T cells showed an increase in liver biopsies from both FH-E [median 53.4 per arbitrary unit area (range 31.2-99.9)] and FH-B [median 49.3 (19.3-51.0); P = 0.005] compared to control liver tissue [median 6.9 (3.1-14.9)].

CONCLUSION: FH-E patients show CD8⁺ T cell infiltration and increased gene expression of cytotoxic T cell pathways in liver, suggesting a possible pathogenetic role for these cells.

Clinical course and management of acute and chronic viral hepatitis during pregnancy

Pregnancy is a para-physiologic condition, which usually evolves without any complications in the majority of women, even if in some circumstances moderate or severe clinical problems can also occur. Among complications occurring during the second and the third trimester very important are those considered as concurrent to pregnancy such as hyperemesis gravidarum, intrahepatic cholestasis of pregnancy, HELLP syndrome and acute fatty liver of pregnancy. The liver diseases concurrent to pregnancy typically occur at specific times during the gestation and they may lead to significant maternal and foetal morbidity and mortality. Commonly, delivery of the foetus, even preterm, usually terminates the progression of these disorders. All chronic liver diseases, such as chronic viral hepatitis, autoimmune hepatitis, Wilson's disease, and cirrhosis of different aetiologies may cause liver damage, independently from pregnancy. In this review we will also comment the clinical implications of pregnancies occurring in women who received a orthotopic liver transplantation (OLT) Therefore, the management of immunosuppressive therapy before and after the delivery in women who received liver transplant is becoming a relevant clinical issue. Finally, we will focus on acute and chronic viral hepatitis occurring during pregnancy, on management of advanced liver disease and we will review the literature on the challenging issue regarding pregnancy and OLT.

Association of cytokines in hepatitis E with pregnancy outcome

AIMS

The aim of this study was to evaluate tumour necrosis factor-alpha (TNF-α), interleukin (IL)-6, interferon gamma (IFN-γ) and transforming growth factor-beta1 (TGF-β1) in hepatitis E infection during pregnancy and its relation with pregnancy outcome.

METHODS

A total of 272 pregnant and 219 non-pregnant women with hepatitis and 262 age and gestational age matched healthy pregnant women and 208 age matched, healthy non-pregnant women were evaluated on the basis of history, clinical examination, liver function profile. Serological tests of hepatitis A, B, C and E and cytokines using commercially available (ELISA) kits. The patients with hepatitis E were further evaluated for viral load by Real Time PCR. All these were followed till delivery for pregnancy outcome.

RESULTS

HEV viral load in acute viral hepatitis (AVH) and fulminant hepatic failure (FHF) of pregnant women were comparatively higher than non-pregnant women. Significantly higher levels of TNF-α, IL-6, IFN-γ and TGF-β1 were present in HEV infected pregnant women compared to non-pregnant women and controls. TNF-α, IL-6 and IFN-γ had significant positive correlation with viral load, serum bilirubin and prothrombin time in pregnant women. Higher levels of all four cytokines were found in pregnant women with HEV infection having adverse pregnancy outcome compared to that of pregnant women with non-HEV infection and controls.

CONCLUSION

In conclusion, severity of HEV infection and associated adverse pregnancy outcome might be mediated by cytokine in pregnancy.

Hepatitis E virus infection

Hepatitis E virus (HEV) infection is a worldwide disease. An improved understanding of the natural history of HEV infection has been achieved within the last decade. Several reservoirs and transmission modes have been identified. Hepatitis E is an underdiagnosed disease, in part due to the use of serological assays with low sensitivity. However, diagnostic tools, including nucleic acid-based tests, have been improved. The epidemiology and clinical features of hepatitis E differ between developing and developed countries. HEV infection is usually an acute self-limiting disease, but in developed countries it causes chronic infection with rapidly progressive cirrhosis in organ transplant recipients, patients with hematological malignancy requiring chemotherapy, and individuals with HIV. HEV also causes extrahepatic manifestations, including a number of neurological syndromes and renal injury. Acute infection usually requires no treatment, but chronic infection should be treated by reducing immunosuppression in transplant patients and/or the use of antiviral therapy. In this comprehensive review, we summarize the current knowledge about the virus itself, as well as the epidemiology, diagnostics, natural history, and management of HEV infection in developing and developed countries.

Evidence of extrahepatic replication of hepatitis E virus in human placenta

The incidence and severity of hepatitis E virus (HEV) infection in pregnant women is high in developing countries. Transplacental transmission of HEV in the third trimester of pregnancy has been found to be associated with high fetal mortality. Based on this evidence and in the absence of reports on HEV replication in extrahepatic sites, this study was carried out to investigate if HEV replication occurs in the placenta of infected mothers. The study included 68 acute viral hepatitis (AVH) and 22 acute liver failure (ALF) pregnant patients. Viral RNA was extracted from blood and placenta. HEV replication in placenta was confirmed by a replicative negative-strand-specific reverse transcriptase PCR. Viral load was estimated by real-time PCR. Immunohistochemical studies were also carried out for in situ detection of HEV in placental tissue sections. Replicative HEV RNA was detectable only in the placenta in ALF and AVH cases and not in blood samples. Positive staining of placental tissue sections with HEV antibody against the viral structural protein ORF3 was observed. HEV replication in placenta also correlated with fetal and maternal mortality in ALF patients. It is demonstrated for the first time that HEV replication occurs in human placenta and that placenta may be a site of extrahepatic replication of HEV in humans.

Hepatitis E: an emerging disease

Currently, the infection with the hepatitis E virus represents the most frequent cause for acute hepatitis and jaundice in the world. According to WHO estimations, around two billion people, representing one third of the world's population, live in endemic areas for HEV and, therefore, are at risk of infection. In developed countries, the circulation of the virus in both human and animal (swine, boar, deer) sewage has been confirmed; however, the incidence rate is low compared to that of developing countries where outbreaks of acute hepatitis transmitted via the fecal-oral route are originated, more frequently in the flooding season or after natural disasters, combined with deficient sanitary conditions. There are currently 4 known genotypes of HEV. Genotypes 1 and 2 are isolated in all human epidemic outbreaks in developing countries, while genotypes 3 and 4 are isolated not only in humans but also in animals, in both developing and industrialized countries. These data support genotypes 3 and 4 having zoonotic nature. The diagnosis of this disease is based in the detection of anti-HEV IgG and IgM in blood serum using enzyme-linked immunosorbent methods. However, the method that best confirms the diagnosis is the RT-PCR, which detects HEV RNA in blood serum and also provides the genotype. The clinical course is generally that of an acute hepatitis which in some cases may require hospitalization and that, in transplant patients or HIV infected individuals can become a chronic hepatitis. Furthermore, the virus constitutes an important risk for pregnant women. The hepatitis E can present a wide range of symptoms, from a subclinical case to chronic liver disease with extrahepatic manifestations. For this reason, the diagnostic is challenging if no differential diagnosis is included. There is no specific antiviral drug for hepatitis E, but satisfactory results have been observed in some patients treated with pegylated interferon alfa2a and/or ribavirin. This revision is an update of all the molecular, epidemiological, clinic and preventive knowledge on this emergent disease up to date.

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.

Clinicolaboratory study of mother-to-neonate transmission of hepatitis E virus in Egypt

OBJECTIVES

To study the presence of hepatitis E viremia in neonates with congenital infections.

METHODS

We included 29 neonates with clinical signs and symptoms suggesting congenital infections, along with their mothers. The control group comprised 29 healthy neonates and their mothers. Laboratory evaluations were performed for each sample for liver function profiles and virological studies for hepatitis viruses B, C, and E.

RESULTS

The most common viral markers in mothers were for hepatitis C immunoglobulin G (IgG) (41%), followed by hepatitis B surface antigen (34%) and hepatitis E virus (HEV) IgG (31%). The most common presentations in neonates were respiratory distress syndrome, followed by preterm birth and signs of sepsis (both 41%) and hepatosplenomegaly (13%).

CONCLUSIONS

This study highlights the occurrence of HEV infection among other etiological conditions causing congenital infections. Vertical transmission from mothers was common in our patients. Although HEV ran a milder course, more studies are needed.

Hepatitis e and acute liver failure in pregnancy

Hepatitis E virus is a positive strand RNA virus with three open reading frames which is transmitted predominantly through the fecal contamination of water and food. It is the most common cause of acute liver failure in endemic areas. Pregnant women especially from the Indian subcontinent and Africa are at increased risk of contracting acute HEV infection as well as developing severe complications including ALF. Transmission of HEV occurs from mother to unborn child. Both maternal and fetal complications may occur, including abortion, fetal demise, preterm labor and maternal or neonatal death. The precise reasons for increased susceptibility to HEV infection during pregnancy and associated severe disease are still an enigma. Management is supportive and termination of pregnancy is not recommended as a general rule. Prevention of infection is of vital importance, as availability of clean drinking water can reduce the burden of this disease in the community. There is a need for future research to focus on prevention of ALF in pregnancy and to study the disease pathogenesis, which is not explicitly understood at present. The availability of a vaccine may alter the natural course of the disease in this select population which is at risk.