Use of hepatitis E IgG avidity for diagnosis of hepatitis E infection

The significance of antigen-antibody-binding avidity in clinical diagnosis

Immunoglobulin G (IgG) and immunoglobulin M (IgM) testing are commonly used to determine infection status. Typically, the detection of IgM indicates an acute or recent infection, while the presence of IgG alone suggests a chronic or past infection. However, relying solely on IgG and IgM antibody positivity may not be sufficient to differentiate acute from chronic infections. This limitation arises from several factors. The prolonged presence of IgM can complicate diagnostic interpretations, and false positive IgM results often arise from antibody cross-reactivity with various antigens. Additionally, IgM may remain undetectable in prematurely collected samples or in individuals who are immunocompromised, further complicating accurate diagnosis. As a result, additional diagnostic tools are required to confirm infection status. Avidity is a measure of the strength of the binding between an antigen and antibody. Avidity-based assays have been developed for various infectious agents, including toxoplasma, cytomegalovirus (CMV), SARS-CoV-2, and avian influenza, and are promising tools in clinical diagnostics. By measuring the strength of antibody binding, they offer critical insights into the maturity of the immune response. These assays are instrumental in distinguishing between acute and chronic or past infections, monitoring disease progression, and guiding treatment decisions. The development of automated platforms has optimized the testing process by enhancing efficiency and minimizing the risk of manual errors. Additionally, the recent advent of real-time biosensor immunoassays, including the label-free immunoassays (LFIA), has further amplified the capabilities of these assays. These advances have expanded the clinical applications of avidity-based assays, making them useful tools for the diagnosis and management of various infectious diseases. This review is structured around several key aspects of IgG avidity in clinical diagnosis, including: (i) a detailed exposition of the IgG affinity maturation process; (ii) a thorough discussion of the IgG avidity assays, including the recently emerged biosensor-based approaches; and (iii) an examination of the applications of IgG avidity in clinical diagnosis. This review is intended to contribute toward the development of enhanced diagnostic tools through critical assessment of the present landscape of avidity-based testing, which allows us to identify the existing knowledge gaps and highlight areas for future investigation.

Laboratory Diagnosis of HEV Infection

Serological and nucleic acid tests for detecting hepatitis E virus (HEV) have been developed for both epidemiologic and diagnostic purposes. The laboratory diagnosis of HEV infection depends on the detection of HEV antigen or HEV RNA in the blood, stool, and other body fluids, and serum antibodies against HEV (immunoglobulin [Ig]A, IgM, and IgG). Anti-HEV IgM antibodies and low avidity IgG can be detected during the acute phase of the illness and can last approximately 12 months, representing primary infection, whereas anti-HEV IgG antibodies can last more than several years, representing remote exposure. Thus, the diagnosis of acute infection is based on the presence of anti-HEV IgM, low avidity IgG, HEV antigen, and HEV RNA, while epidemiological investigations are mainly based on anti-HEV IgG. Although significant progress has been made in developing and optimizing different formats of HEV assays, improving their sensitivity and specificity, there are many shortcomings and challenges in inter-assay concordance, validation, and standardization. This article reviews the current knowledge on the diagnosis of HEV infection, including the most common available laboratory diagnostic techniques.

Hepatitis E Infection in a Longitudinal Cohort of Hepatitis C Virus and HCV/HIV Coinfected Persons

Hepatitis E virus (HEV) is thought to be common in the United States with increased prevalence in those with concomitant hepatitis C virus (HCV) or HCV/HIV coinfection. Little is known regarding true prevalence, incidence, and antibody seroreversion in these populations. We sought to define these rates among HCV and HCV/HIV coinfected persons in the Washington, DC area. Two longitudinal cohorts of HCV and HCV/HIV coinfected subjects from the Washington, DC area were evaluated. Multiple HEV test modalities were deployed including immunoglobulin G (IgG) and immunoglobulin M (IgM) antibody testing, evaluation of antibody avidity, HEV RNA testing, and HEV enzyme-linked immune absorbent spot (ELISPOT) analysis. A total of 379 individuals were evaluated including 196 who were HCV monoinfected and 183 HCV/HIV coinfected. Anti-HEV IgG was detected and confirmed in 18.7% of the cohort at baseline. None demonstrated anti-HEV IgM positive or HEV RNA positive results. Proportions of HEV antibody prevalence did not significantly differ between groups. Longitudinal follow-up samples were available for 226 individuals with a mean follow-up time of 24 months. Seroreversion was noted in 1.8%. One HCV/HIV infected person seroconverted to HEV IgG positivity in the followed cohort. About 40% of the positive population demonstrated high avidity suggestive of more remote exposure. Interferon gamma ELISPOT was performed in 70 subjects and false negative and false positive HEV enzyme-linked immunosorbent assay antibodies were identified. In HIV-infected persons in the United States HEV exposure and seroconversion is frequent enough that HEV should be considered in the differential diagnosis of acute hepatitis. Seroreversion may lead to underestimation of true infection risk.

Anti-HEV IgG Avidity Testing: Utility for Diagnosing Acute and Resolved Genotype 3 Infections

European Association of the Study of the Liver (EASL) guidelines specify HEV RNA, as well as anti-HEV IgG and IgM as positive markers for acute HEV infection. HEV RNA assay sensitivity limitations may lead to false negative test results in patients with low levels of viremia. Moreover, anti-HEV IgM positivity is not a reliable indicator for distinguishing between acute and resolved infections given the ability of this antibody to persist several months after a resolved infection. Our study aims were to assess HEV IgG avidity for diagnosing acute and resolved infections, regardless of the anti-HEV IgM serostatus, and examine assay reliability when evaluating different genotype 3 (GT3) HEV subtypes. Patient serum samples (n = 104) were tested for HEV IgG avidity by utilizing the DIA.PRO kit on a DSX automated instrument. Among patients identified with acute HEV infections, 32 were infected with GT3: GT3c (n = 5), GT3e (n = 8), 3f (n = 17) and GT3-unsubtyped (n = 2). Avidity sensitivity was 91.2% and specificity was 100%. For patients with long-lasting anti-HEV IgM persistence, an Avidity Index >70% was observed. Thus, the DIA.PRO avidity assay may be utilized to distinguish between recently acquired and resolved HEV GT3 infections. However, for equivocal results (Avidity Index > 40–70%), HEV RNA molecular testing will be required to confirm a recent infection.

Parsonage-Turner syndrome associated with hepatitis E infection in immunocompetent patients

Introduction The hepatitis E virus (HEV) is the leading cause of acute hepatitis around the world. In recent years, knowledge has increased concerning extrahepatic manifestations caused by HEV, including neurological manifestations such as Parsonage-Turner syndrome (PTS). PTS is characterized by severe shoulder or arm pain and patchy paresis with muscle weakness. The aim of the present study was to assess the association between HEV and PTS. Materials and Methods We reported two cases of PTS associated with HEV, which were diagnosed in a short period of time in the same village. PTS was diagnosed by physical examination and electrophysiological studies, and serology testing for IgM, low-avidity IgG, and RNA of HEV established the diagnosis of acute HEV infection. Results A 44-year-old man who presented cervicobrachial pain accompanied by paresthesia, dyspnea, and isolated derangement of liver enzymes and 57-year-old women with cervical pain radiated to upper limbs, paresthesia, and liver cytolysis, although, this patient was initially diagnosed as having drug-induced hepatitis. Finally, the diagnosis was Parsonage- Turner syndrome associated with hepatitis e virus. In both patients, symptoms were bilateral and they required hospital admission. Both consumed vegetables are grown in a local patch and the phylogenetic analysis showed genotype 3f. Then, we reviewed the literature on PTS and HEV and we found 62 previously described cases that were more likely to be men (86.20 %) with more frequent bilateral symptoms (85.71 %). Genotype 3 is the most commonly associated. Three of those cases were diagnosed in Spain. Conclusions According to our findings, HEV should be considered in patients with neuralgic amyotrophy, including those with the absence of liver cytolysis.

Quantitative evaluation of protective antibody response induced by hepatitis E vaccine in humans

Efficacy evaluation through human trials is crucial for advancing a vaccine candidate to clinics. Next-generation sequencing (NGS) can be used to quantify B cell repertoire response and trace antibody lineages during vaccination. Here, we demonstrate this application with a case study of Hecolin®, the licensed vaccine for hepatitis E virus (HEV). Four subjects are administered the vaccine following a standard three-dose schedule. Vaccine-induced antibodies exhibit a high degree of clonal diversity, recognize five conformational antigenic sites of the genotype 1 HEV p239 antigen, and cross-react with other genotypes. Unbiased repertoire sequencing is performed for seven time points over six months of vaccination, with maturation pathways characterize for a set of vaccine-induced antibodies. In addition to dynamic repertoire profiles, NGS analysis reveals differential patterns of HEV-specific antibody lineages and highlights the necessity of the long vaccine boost. Together, our study presents a quantitative strategy for vaccine evaluation in small-scale human studies.

Analysis of IgG Anti-HEV Antibody Protective Levels During Hepatitis E Virus Reinfection in Experimentally Infected Rhesus Macaques

BACKGROUND

Secondary spread of hepatitis E virus (HEV) infection occurs often in endemic settings in developing countries. The host immune signatures contributing to protection against subsequent HEV reinfection are unknown.

METHODS

Twelve seroconverted rhesus macaques were reinoculated with homologous HEV genotype 1 (gt1, Sar-55) and followed for 115 days. HEV RNA, HEV-specific T-cell responses, IgG anti-HEV antibody, and the IgG anti-HEV avidity index were tested.

RESULTS

Four animals with baseline IgG anti-HEV levels from 1.5 to 13.4 World Health Organization (WHO) U/mL evidenced reinfection as determined by HEV RNA in stool, and increase in IgG anti-HEV levels between 63- and 285-fold (P = .003). Eight animals with baseline IgG anti-HEV levels from 2.8 to 90.7 WHO U/mL did not develop infection or shed virus in feces, and IgG anti-HEV antibody levels were unchanged (P = .017). The 4 reinfected animals showed a lower HEV-IgG avidity index (average 35.5%) than the 8 protected animals (average 62.1%). HEV-specific interferon-gamma-producing T cells were 2-fold higher in reinfected animals (P = .018).

CONCLUSIONS

Preexisting antibody and high IgG avidity index (>50%) are important factors for protection against HEV reinfection. HEV-specific T-cell responses were elevated in reinfected animals after subsequent exposure to HEV.

Evaluation of protective efficacy induced by different heterologous prime-boost strategies encoding triosephosphate isomerase against Schistosoma japonicum in mice

BACKGROUND

In China, schistosomiasis japonica is a predominant zoonotic disease, and animal reservoir hosts in the environment largely sustain infections. The development of transmission-blocking veterinary vaccines is urgently needed for the prevention and efficient control of schistosomiasis. Heterologous prime-boost strategy is more effective than traditional vaccination and homologous prime-boost strategies against multiple pathogens infection. In the present study, to further improve protective efficacy, we immunized mice with three types of heterologous prime-boost combinations based on our previously constructed vaccines that encode triosphate isomerase of Schistosoma japonicum, tested the specific immune responses, and evaluated the protective efficacy through challenge infection in mice.

METHODS

DNA vaccine (pcDNA3.1-SjTPI.opt), adenoviral vectored vaccine (rAdV-SjTPI.opt), and recombinant protein vaccine (rSjTPI) were prepared and three types of heterologous prime-boost combinations, including DNA i.m. priming-rAdV i.m. boosting, rAdV i.m. priming-rAdV s.c. boosting, and rAdV i.m. priming-rSjTPI boosting strategies, were carried out. The specific immune responses and protective efficacies were evaluated in BALB/c mice RESULTS: Results show that different immune profiles and various levels of protective efficacy were elicited by using different heterologous prime-boost combinations. A synergistic effect was observed using the DNA i.m. priming-rAdV i.m. boosting strategy; however, its protective efficacy was similar to that of rAdV i.m. immunization. Conversely, an antagonistic effect was generated by using the rAd i.m. priming-s.c. boosting strategy. However, the strategy, with rAdV i.m. priming- rSjTPI s.c. boosting, generated the most optimal protective efficacy and worm or egg reduction rate reaching up to 70% in a mouse model.

CONCLUSIONS

A suitable immunization strategy, rAdV i.m. priming-rSjTPI boosting strategy, was developed, which elicits a high level of protective efficacy against Schistosoma japonicum infection in mice.

Current Knowledge on Hepatitis E

Although only a single serotype of hepatitis E virus (HEV), the causative agent of hepatitis E, has been identified, there is great genetic variation among the different HEV isolates reported. There are at least four major recognized genotypes of HEV: genotypes 1 and 2 are mainly restricted to humans and linked to epidemic outbreaks in nonindustrialized countries, whereas genotypes 3 and 4 are zoonotic in both developing and industrialized countries. Besides human strains, genotype 3 and 4 strains of HEV have been genetically characterized from swine, sika deer, mongooses, sheep, and rabbits. Currently, there are approximately 11,000 human and animal sequences of HEV available at the International Nucleotide Sequence Database Collaboration. HEV is the major cause of waterborne outbreaks of hepatitis in areas of poor sanitation. Additionally, it is responsible for sporadic cases of viral hepatitis in not only endemic but industrialized countries as well. Transmission of HEV occurs predominantly by the fecal-oral route, although parenteral and perinatal routes have been reported. HEV infection develops in most individuals as a self-limiting, acute, icteric hepatitis; with mortality rates around 1%. However, some affected individuals will develop fulminant hepatic failure, a serious condition that is frequently fatal without a liver transplant. This complication is particularly common when the infection occurs in pregnant women, where mortality rates rise dramatically to up to 25%. Among the preventive measures available to avoid HEV infection, two separate subunit vaccines containing recombinant truncated capsid proteins of HEV have been shown to be highly effective in the prevention of disease. One of them, HEV 239, was approved in China, and its commercialization by Innovax began in November 2012 under the name Hecolin(®).

Enhancement of protective efficacy through adenoviral vectored vaccine priming and protein boosting strategy encoding triosephosphate isomerase (SjTPI) against Schistosoma japonicum in mice

Background

Schistosomiasis japonica is a zoonotic parasitic disease; developing transmission blocking veterinary vaccines are urgently needed for the prevention and control of schistosomiasis in China. Heterologous prime-boost strategy, a novel vaccination approach, is more effective in enhancing vaccine efficacy against multiple pathogens. In the present study, we established a novel heterologous prime-boost vaccination strategy, the rAdV-SjTPI.opt intramuscular priming and rSjTPI subcutaneous boosting strategy, and evaluated its protective efficacy against Schistosoma japonicum in mice.

Methodology/Principal Findings

Adenoviral vectored vaccine (rAdV-SjTPI.opt) and recombinant protein vaccine (rSjTPI) were prepared and used in different combinations as vaccines in a mouse model. The specific immune responses and protective efficacies were evaluated. Furthermore, the longevity of protective efficacy was also determined. Results showed that the rAdV-SjTPI.opt priming-rSjTPI boosting strategy elicited higher levels of specific IgG responses and broad-spectrum specific cellular immune responses. The protective efficacy could reach up to nearly 70% and 50% of protection could be observed at 10 weeks after the last immunization in mice.

Conclusions/Significance

The rAdV-SjTPI.opt intramuscular priming-rSjTPI subcutaneous boosting vaccination strategy is a novel, highly efficient, and stable approach to developing vaccines against Schistosoma japonicum infections in China.

Detailed investigation of ongoing subclinical hepatitis E virus infections; occurring in outbreak settings of North India

BACKGROUND & AIMS

Every year globally WHO reports 20 million Hepatitis E virus (HEV) infections. The disease occurs as sporadic cases or focused outbreaks and has potentials to cause massive epidemics. The reservoir of HEV during inter-epidemic period is not well characterized. The sporadic cases usually lack history of contact with clinically overt HEV patients. In the present context we evaluated the occurrence of subclinical HEV as a possible reservoir in endemic region.

METHODS

Blood samples were collected from 67 apparently healthy individuals and 10 acute viral hepatitis (AVH) patients during two HEV outbreaks in North India. The serum samples were tested for anti-HEV IgM, IgG, HEV-IgG avidity index, HEV viral load and conventional-PCR followed by sequencing and phylogenetic analysis.

RESULTS

A total of 14 (20.89%) apparently healthy individuals showed the presence of anti-HEV IgM and IgG. Of 14 based on HEV-IgG avidity index, 9 (64.28%) had secondary-exposure, 4 (28.57%) had primary exposure, while one patient had intermediate avidity. Subclinical subjects with primary exposure had significantly higher anti-HEV IgM index as compared to secondary-exposure (P = 0.0028). Viral load in clinically jaundiced patients was significantly higher as compared to subclinical subjects (P < 0.0001). Phylogenetic analysis showed HEV sequences retrieved from subclinical individuals clustered along with AVH patients, suggesting matched source. The significantly low viral load in subclinical subjects hints towards the dose dependency for progression of clinical manifestation.

CONCLUSION

We document subclinical HEV with low level viremia occurs during outbreak settings and goes un-noticed, which helps maintaining the virus in nature possibly leading to its endemicity.

Hepatitis E virus reinfections in solid-organ-transplant recipients can evolve into chronic infections

BACKGROUND

Hepatitis E virus (HEV) infections are a major cause of acute hepatitis in developing and industrialized countries. Little is known about anti-HEV immunity in solid-organ recipients.

METHODS

We screened 263 solid-organ recipients for anti-HEV immunoglobulin G (IgG) at transplantation. They were followed up for 1 year and tested for HEV RNA and anti-HEV antibodies 1 year after transplantation and if their liver enzyme activities increased.

RESULTS

A total of 38.4% had anti-HEV IgG at transplantation. The mean concentrations (±SD) of anti-HEV IgG at transplantation (8 ± 17.5 U/mL) and 1 year later (6.4 ± 12.0 U/mL, P = .4) were similar. There were 3 de novo HEV infections during the 1-year follow-up among patients who were HEV seronegative before transplantation, giving an annual incidence of 2.1%. We also identified 3 HEV reinfections among patients who were seropositive before transplantation through detection of HEV RNA, for an annual incidence of 3.3%. Their anti-HEV IgG concentrations were 0.3, 2.1, and 6.2 World Health Organization (WHO) units/mL before transplantation. Reinfection of the patient with the lowest IgG concentration at transplantation had evolved to a chronic infection.

CONCLUSIONS

Low anti-HEV antibodies (<7 WHO units/mL) seemed not to protect solid-organ recipients. HEV reinfection in immunocompromised patients can lead to chronic infection, as in primary infections.

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.

Hepatitis E: current status

Acute hepatitis E is a very common disease in developing countries, to the point that, according to World Health Organization estimates, one third of the world's population has been exposed to HEV. It also causes outbreaks in refugee camps or after natural disasters such as floods or earthquakes. Sporadic cases of acute hepatitis have been observed in practically all European countries and other developed geographical areas, not only in travelers from endemic countries but also in people with no risk factors. But, lately, new aspects of this infection are appearing in industrialized countries such as the possibility of the disease becoming chronic in transplant patients, the immunocompromised in general, and even in patients with previous liver disease who are immunocompetent. In this comprehensive review, we summarize the current knowledge on HEV infection.

An analysis of the benefit of using HEV genotype 3 antigens in detecting anti-HEV IgG in a European population

Background

The benefit of using serological assays based on HEV genotype 3 in industrialised settings is unclear. We compared the performance of serological kits based on antigens from different HEV genotypes.

Methods

Taking 20 serum samples from patients in southwest France with acute HEV infection (positive PCR for HEV genotype 3) and 550 anonymised samples from blood donors in southwest Switzerland, we tested for anti-HEV IgG using three enzyme immunoassays (EIAs) (MP Diagnostics, Dia.Pro and Fortress) based on genotype 1 and 2 antigens, and one immunodot assay (Mikrogen Diagnostik recomLine HEV IgG/IgM) based on genotype 1 and 3 antigens.

Results

All acute HEV samples and 124/550 blood donor samples were positive with ≥1 assay. Of PCR-confirmed patient samples, 45%, 65%, 95% and 55% were positive with MP Diagnostics, Dia.Pro, Fortress and recomLine, respectively. Of blood donor samples positive with ≥1 assay, 120/124 (97%), were positive with Fortress, 19/124 (15%) were positive with all EIAs and 51/124 (41%) were positive with recomLine. Of 11/20 patient samples positive with recomLine, stronger reactivity for HEV genotype 3 was observed in 1/11(9%), and equal reactivity for both genotypes in 5/11 (45.5%).

Conclusions

Although recomLine contains HEV genotype 3, it has lower sensitivity than Fortress in acute HEV infection and fails to identify infection as being due to this genotype in approximately 45% of patients. In our single blood donor population, we observe wide variations in measured seroprevalence, from 4.2% to 21.8%, depending on the assay used.

Antigenic determinants of hepatitis E virus and vaccine-induced immunogenicity and efficacy

There is emerging evidence for an under-recognized hepatitis E virus (HEV) as a human pathogen. Among different reasons for this neglect are the unsatisfactory performance and under-utilization of commercial HEV diagnostic kits; for instance, the number of anti-HEV IgM kits marketed in China is about one-fifth of that of hepatitis A kits. Over the last two decades, substantial progress has been achieved in furthering our knowledge on the HEV-specific immune responses, antigenic features of HEV virions, and development of serological assays and more recently prophylactic vaccines. This review will focus on presenting the evidence of the importance of HEV infection for certain cohorts such as pregnant women, the key antigenic determinants of the virus, and immunogenicity and clinical efficacy conferred by a newly developed prophylactic vaccine. Robust immunogenicity, greater than 195-fold and approximately 50-fold increase of anti-HEV IgG level in seronegative and seropositive vaccinees, respectively, as well as impressive clinical efficacy of this vaccine was demonstrated. The protection rate against the hepatitis E disease and the virus infection was shown to be 100% (95% CI 75-100) and 78% (95% CI 66-86), respectively.

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.

Serological diagnostics of hepatitis E virus infection

Development of accurate diagnostic assays for the detection of serological markers of hepatitis E virus (HEV) infection remains challenging. In the course of nearly 20 years after the discovery of HEV, significant progress has been made in characterizing the antigenic structure of HEV proteins, engineering highly immunoreactive diagnostic antigens, and devising efficient serological assays. However, many outstanding issues related to sensitivity and specificity of these assays in clinical and epidemiological settings remain to be resolved. Complexity of antigenic composition, viral genetic heterogeneity and varying epidemiological patterns of hepatitis E in different parts of the world present challenges to the refinement of HEV serological diagnostic assays. Development of antigens specially designed for the identification of serological markers specific to acute infection and of IgG anti-HEV specific to the convalescent phase of infection would greatly facilitate accurate identification of active, recent and past HEV infections.

Hepatitis E virus infection in HIV-infected patients with elevated serum transaminases levels

Increases in aminotransferases levels are frequently encountered in HIV-positive patients and often remain unexplained. The role in this setting and natural history of hepatitis E in HIV-infected patients are unknown. The aim of the study was to assess HEV infection in HIV-infected patients attending a Parisian hospital, with a current or previous cryptogenic hepatitis.191 plasma samples collected from 108 HIV-infected patients with elevated aminotransferases levels were retrospectively tested for the presence of hepatitis E virus (HEV) infection markers: anti-HEV IgM antibodies, anti-HEV IgG antibodies, anti-HEV IgG avidity index and plasma HEV RNA.One acute infection, documented by positive tests for anti-HEV IgM antibody, low anti-HEV IgG avidity index and plasma HEV RNA (genotype 3e), and three past infections were diagnosed, without any observed case of persistent infection. The acute hepatitis was benign and resolved spontaneously within two weeks. This infection was probably contracted locally. Acute HEV hepatitis can occur in HIV-infected patients but rarely explains cryptogenic hepatitis, at least in an urban HIV population, regardless geographic origin and CD4 counts.

Hepatitis E virus in HIV-infected patients

OBJECTIVES

Many cases of acute autochthonous hepatitic E virus (HEV) hepatitis have been reported in France, mainly from the south. Chronic HEV infection has recently been described in immunosuppressed patients. Although a potential risk of chronicity exists in HIV-infected patients, no survey has been conducted in this population. The aim of this study was to assess the sero-virological prevalence of HEV in French HIV-infected patients.

METHODS

Two hundred and forty-five HIV-infected patients followed at two Infectious Diseases Departments (one in the south, one in the north) were included from January to March 2009. Sera were collected from all patients and tested using anti-HEV IgG and IgM kits. HEV RNA was systematically amplified in the ORF2 region with an in-house method. The IgG avidity index of all IgG-positive samples was determined.

RESULTS

Three of the 133 southern patients showed both anti-HEV IgG and IgM positivities, along with cytolysis and biological cholestasis; HEV RNA was amplified in two of these cases, whereas a low IgG avidity index was observed in all three samples. Twelve of the 130 remaining southern patients (9%) showed anti-HEV IgG positivity. The serological prevalence in the 112 northern patients was 3%, which was significantly lower than in the southern patients (P=0.04). No case of acute hepatitis was reported in the north, whereas the prevalence of patients with biochemical liver abnormalities was similar in both areas (P=0.22).

CONCLUSIONS

In France, HIV-infected patients are at risk of HEV infection with a serological north-to-south gradient. No case of chronic HEV infection was detected in this study.

Zoonotic hepatitis E: animal reservoirs and emerging risks

Hepatitis E virus (HEV) is responsible for enterically-transmitted acute hepatitis in humans with two distinct epidemiological patterns. In endemic regions, large waterborne epidemics with thousands of people affected have been observed, and, in contrast, in non-endemic regions, sporadic cases have been described. Although contaminated water has been well documented as the source of infection in endemic regions, the modes of transmission in non-endemic regions are much less known. HEV is a single-strand, positive-sense RNA virus which is classified in the Hepeviridae family with at least four known main genotypes (1–4) of mammalian HEV and one avian HEV. HEV is unique among the known hepatitis viruses, in which it has an animal reservoir. In contrast to humans, swine and other mammalian animal species infected by HEV generally remain asymptomatic, whereas chickens infected by avian HEV may develop a disease known as Hepatitis-Splenomegaly syndrome. HEV genotypes 1 and 2 are found exclusively in humans while genotypes 3 and 4 are found both in humans and other mammals. Several lines of evidence indicate that, in some cases involving HEV genotypes 3 and 4, animal to human transmissions occur. Furthermore, individuals with direct contact with animals are at higher risk of HEV infection. Cross-species infections with HEV genotypes 3 and 4 have been demonstrated experimentally. However, not all sources of human infections have been identified thus far and in many cases, the origin of HEV infection in humans remains unknown.