Analysis of full-length hepatitis A virus genome in sera from patients with fulminant and self-limited acute type A hepatitis

Artificial intelligence and machine learning could support drug development for hepatitis A virus internal ribosomal entry sites

Hepatitis A virus (HAV) infection is still an important health issue worldwide. Although several effective HAV vaccines are available, it is difficult to perform universal vaccination in certain countries. Therefore, it may be better to develop antivirals against HAV for the prevention of severe hepatitis A. We found that several drugs potentially inhibit HAV internal ribosomal entry site-dependent translation and HAV replication. Artificial intelligence and machine learning could also support screening of anti-HAV drugs, using drug repositioning and drug rescue approaches.

Outbreak of hepatitis A virus infection in Taiwan, June 2015 to September 2017

The Taiwan Centers for Disease Control (CDC) were notified of increasing acute hepatitis A (AHA) in June 2015. Serum and/or stool from AHA patients and sewage samples were tested for hepatitis A virus (HAV). We defined outbreak cases as AHA patients with illness onset after June 2015 and with an HAV sequence less than 0.5% different from that of the TA-15 outbreak strain. We analysed characteristics and food exposures between outbreak and non-outbreak cases between January 2014 (start of enhanced surveillance) and February 2016. From June 2015 to September 2017, there were 1,563 AHA patients with a median age of 31 years (interquartile range (IQR): 26–38); the male-to-female ratio was 8.8 and 585 (37%) had human immunodeficiency virus (HIV) infection. TA-15 was detected in 82% (852/1,033) of AHA patients, and 14% (74/540) of sewage samples tested since July 2015. Infection with the TA-15 strain was associated with having HIV, sexually transmitted infections (STI), recent oral-anal sex and men who have sex with men (MSM). The Taiwan CDC implemented an HAV vaccine campaign starting from October 2016 where 62% (15,487/24,879) of people at risk were vaccinated against HAV. We recommend HAV vaccination for at-risk populations and continuous surveillance to monitor control measures.

Origin of HAV strains responsible for 2016-2017 outbreak among MSM: Viral phylodynamics in Lazio region

In Europe HAV infection occurs mainly among specific risk groups, such as consumers of specific food. Sexual transmission of HAV has been demonstrated, particularly among Men-Who-Have-Sex-With-Men (MSM), causing MSM-specific outbreaksin Europe. Here we report a molecular epidemiologic and phylodynamic analysis on HAV sequences in Lazio (central Italy)to identify genetic background and the phylogenetic relations, and test the HAV infection dynamics during a large outbreak through phylodynamic model.Among all HAV sequences found during 2013-2018 in Lazio, low genetic diversity was observed in HAV population in 2016 and 2017, along with high frequenciesVRD_521_2016and RIVM-HAV16-090, suggesting a large expansion event of viral population. The initial expansion of both VRD_521_2016 and RIVM-HAV16-090 clusters dated back to 2012 (95% HPD:2006-2015). During the2016-2017outbreak in Lazio region, the Re peaked around mid-2016, with a value of 1.73 (95% HPD: 1.03-2.37), consistent with incidence trend of AHA cases in Lazio between 2016 and mid-2017. This study showed the magnitude of HAV outbreak in Lazio during 2016-2017, demonstrating the epidemic continuity to MSM-specific outbreak in Europe. The HAV dataset is available on interactive phylodynamic platform https://nextstrain.org to real-time update of future outbreaks.

Human genetic basis of fulminant viral hepatitis

In rare cases, hepatitis A virus (HAV) and hepatitis B virus (HBV) can cause fulminant viral hepatitis (FVH), characterized by massive hepatocyte necrosis and an inflammatory infiltrate. Other viral etiologies of FVH are rarer. FVH is life-threatening, but the patients are typically otherwise healthy, and normally resistant to other microbes. Only a small minority of infected individuals develop FVH, and this is the key issue to be addressed for this disease. In mice, mouse hepatitis virus 3 (MHV3) infection is the main model for dissecting FVH pathogenesis. Susceptibility to MHV3 differs between genetic backgrounds, with high and low mortality in C57BL6 and A/J mice, respectively. FVH pathogenesis in mice is related to uncontrolled inflammation and fibrinogen deposition. In humans, FVH is typically sporadic, but rare familial forms also exist, suggesting that there may be causal monogenic inborn errors. A recent study reported a single-gene inborn error of human immunity underlying FVH. A patient with autosomal recessive complete IL-18BP deficiency was shown to have FVH following HAV infection. The mechanism probably involves enhanced IL-18- and IFN-γ-dependent killing of hepatocytes by NK and CD8 T cytotoxic cells. Proof-of-principle that FVH can be genetic is important clinically, for the affected patients and their families, and immunologically, for the study of immunity to viruses in the liver. Moreover, the FVH-causing IL18BP genotype suggests that excessive IL-18 immunity may be a general mechanism underlying FVH, perhaps through the enhancement of IFN-γ immunity.

Emerging hepatitis E virus compared with hepatitis A virus: A new sanitary challenge

Hepatitis A (HAV) and E (HEV) viruses are able to cause liver disease in humans. Among the five classical hepatotropic viruses, they are mainly transmitted via the fecal-oral route. Historically, many similarities have thus been described between them according to their incidence and their pathogenicity, especially in countries with poor sanitary conditions. However, recent advances have provided new insights, and the gap is widening between them. Indeed, while HAV infection incidence tends to decrease in developed countries along with public health improvement, HEV is currently considered as an underdiagnosed emerging pathogen. HEV autochthonous infections are increasingly observed and are mainly associated with zoonotic transmissions. Extra hepatic signs resulting in neurological or renal impairments have also been reported for HEV, as well as a chronic carrier state in immunocompromised patients, arguing in favor of differential pathogenesis between those two viruses. Recent molecular tools have allowed studies of viral genome variability and investigation of links between viral plasticity and clinical evolution. The identification of key functional mutations in viral genomes may improve the knowledge of their clinical impact and is analyzed in depth in the present review.

Inherited IL-18BP deficiency in human fulminant viral hepatitis

Fulminant viral hepatitis (FVH) is a devastating and unexplained condition that strikes otherwise healthy individuals during primary infection with common liver-tropic viruses. We report a child who died of FVH upon infection with hepatitis A virus (HAV) at age 11 yr and who was homozygous for a private 40-nucleotide deletion in IL18BP, which encodes the IL-18 binding protein (IL-18BP). This mutation is loss-of-function, unlike the variants found in a homozygous state in public databases. We show that human IL-18 and IL-18BP are both secreted mostly by hepatocytes and macrophages in the liver. Moreover, in the absence of IL-18BP, excessive NK cell activation by IL-18 results in uncontrolled killing of human hepatocytes in vitro. Inherited human IL-18BP deficiency thus underlies fulminant HAV hepatitis by unleashing IL-18. These findings provide proof-of-principle that FVH can be caused by single-gene inborn errors that selectively disrupt liver-specific immunity. They also show that human IL-18 is toxic to the liver and that IL-18BP is its antidote.

Classification and Genomic Diversity of Enterically Transmitted Hepatitis Viruses

Hepatitis A virus (HAV) and hepatitis E virus (HEV) are significant human pathogens and are responsible for a substantial proportion of cases of severe acute hepatitis worldwide. Genetically, both viruses are heterogeneous and are classified into several genotypes that differ in their geographical distribution and risk group association. There is, however, little evidence that variants of HAV or HEV differ antigenically or in their propensity to cause severe disease. Genetically more divergent but primarily hepatotropic variants of both HAV and HEV have been found in several mammalian species, those of HAV being classified into eight species within the genus Hepatovirus in the virus family Picornaviridae. HEV is classified as a member of the species Orthohepevirus A in the virus family Hepeviridae, a species that additionally contains viruses infecting pigs, rabbits, and a variety of other mammalian species. Other species (Orthohepevirus B-D) infect a wide range of other mammalian species including rodents and bats.

Detection and characterization of hepatitis A virus circulating in Egypt

Hepatitis A virus (HAV) still poses a considerable problem worldwide. In the current study, hepatitis A virus was recovered from wastewater samples collected from three wastewater treatment plants over one year. Using RT-PCR, HAV was detected in 43 out of 68 samples (63.2%) representing both inlet and outlet. Eleven positive samples were subjected to sequencing targeting the VP1-2A junction region. Phylogenetic analysis revealed that all samples belonged to subgenotype IB with few substitutions at the amino acid level. The complete sequence of one isolate (HAV/Egy/BI-11/2015) showed that the similarity at the amino acid level was not reflected at the nucleotide level. However, the deduced amino acid sequence derived from the complete nucleotide sequence showed distinct substitutions in the 2B, 2C, and 3A regions. Recombination analysis revealed a recombination event between X75215 (subgenotype IA) and AF268396 (subgenotype IB) involving a portion of the 2B nonstructural protein coding region (nucleotides 3757-3868) assuming the herein characterized sequence an actual recombinant. Despite the role of recombination in picornaviruses evolution, its involvement in HAV evolution has rarely been reported, and this may be due to the limited available complete HAV sequences. To our knowledge, this represents the first characterized complete sequence of an Egyptian isolate and the described recombination event provides an important update on the circulating HAV strains in Egypt.

Hepatitis A virus genotype IA-infected patient with marked elevation of aspartate aminotransferase levels

We describe a case of acute liver failure (ALF) without hepatic encephalopathy with marked elevation of aminotransferase due to hepatitis A, according to the revised Japanese criteria of ALF. This liver biopsy of the patient showed compatible to acute viral hepatitis and she immediately recovered without intensive care. She had no comorbid disorders. Of interest, phylogenetic tree analysis using almost complete genomes of hepatitis A virus (HAV) demonstrated that the HAV isolate from her belonged to the HAV subgenotype IA strain and was similar to the HAJFF-Kan12 strain (99% nucleotide identity) or FH1 strain (98% nucleotide identity), which is associated with severe or fulminant hepatitis A. Careful interpretation of the association between HAV genome variations and severity of hepatitis A is needed and the mechanism of the severe hepatitis should be explored.

Molecular analysis of hepatitis A virus strains obtained from patients with acute hepatitis A in Mongolia, 2004-2013

Despite the high endemicity of hepatitis A virus (HAV) in Mongolia, the genetic information on those HAV strains is limited. Serum samples obtained from 935 patients with acute hepatitis in Ulaanbaatar, Mongolia during 2004-2013 were tested for the presence of HAV RNA using reverse transcription-PCR with primers targeting the VP1-2B region (481 nucleotides, primer sequences at both ends excluded). Overall, 180 patients (19.3%) had detectable HAV RNA. These 180 isolates shared 94.6-100% identity and formed four phylogenetic clusters within subgenotype IA. One or three representative HAV isolates from each cluster exhibited 2.6-3.9% difference between clusters over the entire genome. Cluster 1 accounted for 65.0% of the total, followed by Cluster 2 (30.6%), Cluster 3 (3.3%), and Cluster 4 (1.1%). Clusters 1 and 2 were predominant throughout the observation period, whereas Cluster 3 was undetectable in 2009 and 2013 and Cluster 4 became undetectable after 2009. The Mongolian HAV isolates were closest to those of Chinese or Japanese origin (97.7-98.5% identities over the entire genome), suggesting the evolution from a common ancestor with those circulating in China and Japan. Further molecular epidemiological analyses of HAV infection are necessary to investigate the factors underlying the spread of HAV and to implement appropriate prevention measures in Mongolia.

Clinical Factors and Viral Load Influencing Severity of Acute Hepatitis A

Background and Aims

Clinical manifestations of hepatitis A virus (HAV) infection vary from mild to fulminant hepatic failure (FHF) in adults. We investigated the relationship between laboratory findings, including viral load, and clinical outcomes in patients with acute hepatitis A (AHA) and evaluated predictive factors for severe acute hepatitis (s-AH).

Methods

We analyzed the clinical manifestations of AHA in 770 patients. Patients with a prothrombin time (PT) of less than 40% of normal were classified as s-AH and included 4 patients with FHF, 11 patients with acute renal failure, and 3 patients with prolonged jaundice (n = 128). Other patients were defined as mild acute hepatitis (m-AH) (n = 642). Serum samples were obtained from 48 patients with acute hepatitis A. Among them, 20 with s-AH, and 28 with m-AH, were tested for HAV RNA titer.

Results

In a multivariate analysis, age (HR = 1.042, P = 0.041), peak creatinine (HR = 4.014, P = 0.001), bilirubin (HR = 1.153, P = 0.003), alanine aminotransferase (ALT) (HR = 1.001, P<0.001), initial lactate dehydrogenase (LDH) (HR = 1.000, P = 0.045) and total cholesterol (HR = 0.978, P<0.001) were independent factors for s-AH. Serum HAV RNA was detected in 20/20 (100%) patients with s-AH and 22/28 (78.6%) patients with m-AH. In a multivariate analysis of the 48 patients who were tested for HAV RNA, peak ALT (HR = 1.001, P = 0.004) and HAV RNA titer (HR = 2.076, P = 0.012) were independent factors for s-AH.

Conclusions

Clinical factors including age, peak creatinine, bilirubin, ALT, initial LDH and total cholesterol were independent factors for s-AH in a multivariate analysis. In particular, HAV load strongly correlated with the severity of hepatitis A.

Ultra-deep sequencing analysis of the hepatitis A virus 5'-untranslated region among cases of the same outbreak from a single source

Hepatitis A virus (HAV) is a causative agent of acute viral hepatitis for which an effective vaccine has been developed. Here we describe ultra-deep pyrosequences (UDPSs) of HAV 5'-untranslated region (5'UTR) among cases of the same outbreak, which arose from a single source, associated with a revolving sushi bar. We determined the reference sequence from HAV-derived clone from an attendant by the Sanger method. Sixteen UDPSs from this outbreak and one from another sporadic case were compared with this reference. Nucleotide errors yielded a UDPS error rate of < 1%. This study confirmed that nucleotide substitutions of this region are transition mutations in outbreak cases, that insertion was observed only in non-severe cases, and that these nucleotide substitutions were different from those of the sporadic case. Analysis of UDPSs detected low-prevalence HAV variations in 5'UTR, but no specific mutations associated with severity in these outbreak cases. To our surprise, HAV strains in this outbreak conserved HAV IRES sequence even if we performed analysis of UDPSs. UDPS analysis of HAV 5'UTR gave us no association between the disease severity of hepatitis A and HAV 5'UTR substitutions. It might be more interesting to perform ultra-deep sequencing of full length HAV genome in order to reveal possible unknown genomic determinants associated with disease severity. Further studies will be needed.

Genetic relatedness among hepatitis A virus strains associated with food-borne outbreaks

The genetic characterization of hepatitis A virus (HAV) strains is commonly accomplished by sequencing subgenomic regions, such as the VP1/P2B junction. HAV genome is not extensively variable, thus presenting opportunity for sharing sequences of subgenomic regions among genetically unrelated isolates. The degree of misrepresentation of phylogenetic relationships by subgenomic regions is especially important for tracking transmissions. Here, we analyzed whole-genome (WG) sequences of 101 HAV strains identified from 4 major multi-state, food-borne outbreaks of hepatitis A in the Unites States and from 14 non-outbreak-related HAV strains that shared identical VP1/P2B sequences with the outbreak strains. Although HAV strains with an identical VP1/P2B sequence were specific to each outbreak, WG were different, with genetic diversity reaching 0.31% (mean 0.09%). Evaluation of different subgenomic regions did not identify any other section of the HAV genome that could accurately represent phylogenetic relationships observed using WG sequences. The identification of 2–3 dominant HAV strains in 3 out of 4 outbreaks indicates contamination of the implicated food items with a heterogeneous HAV population. However, analysis of intra-host HAV variants from eight patients involved in one outbreak showed that only a single sequence variant established infection in each patient. Four non-outbreak strains were found closely related to strains from 2 outbreaks, whereas ten were genetically different from the outbreak strains. Thus, accurate tracking of HAV strains can be accomplished using HAV WG sequences, while short subgenomic regions are useful for identification of transmissions only among cases with known epidemiological association.

Hepatitis A virus: host interactions, molecular epidemiology and evolution

Infection with hepatitis A virus (HAV) is the commonest viral cause of liver disease and presents an important public health problem worldwide. Several unique HAV properties and molecular mechanisms of its interaction with host were recently discovered and should aid in clarifying the pathogenesis of hepatitis A. Genetic characterization of HAV strains have resulted in the identification of different genotypes and subtypes, which exhibit a characteristic worldwide distribution. Shifts in HAV endemicity occurring in different parts of the world, introduction of genetically diverse strains from geographically distant regions, genotype displacement observed in some countries and population expansion detected in the last decades of the 20th century using phylogenetic analysis are important factors contributing to the complex dynamics of HAV infections worldwide. Strong selection pressures, some of which, like usage of deoptimized codons, are unique to HAV, limit genetic variability of the virus. Analysis of subgenomic regions has been proven useful for outbreak investigations. However, sharing short sequences among epidemiologically unrelated strains indicates that specific identification of HAV strains for molecular surveillance can be achieved only using whole-genome sequences. Here, we present up-to-date information on the HAV molecular epidemiology and evolution, and highlight the most relevant features of the HAV-host interactions.

Complete coding sequence and molecular analysis of hepatitis A virus from a chimpanzee with fulminant hepatitis

BACKGROUND

Hepatitis A virus (HAV) infects both humans and non-human primates, in experimentally infected chimpanzees is typically milder than in humans. In 1982, Abe and Shikata reported a first case of a chimpanzee with fulminant hepatitis caused by spontaneous HAV infection, and the underlying mechanisms of the disease remain unknown.

METHODS

To characterize denoted CFH-HAV, we conducted cloning and near full-length sequence analysis.

RESULTS

Phylogenetic analyses of VP1-2A and complete sequence comparison between various genotypes and the sample sequence showed clustering in genotype IB. Based on BLAST analysis, the sequence was most closely related to the wild-type (HM175/WT) isolate. Amino acid and nucleic acid similarities were 99.8% and 94.41%, respectively.

CONCLUSIONS

The chimpanzee may have been infected with human HAV genotype IB. The substitutions in VP2, VP4, 2B, 2C, and 3D, which may enhance virus proliferation, contributed to disease severity culminating in fulminant hepatic failure.

Clinical features and outcomes of acute kidney injury among patients with acute hepatitis A

BACKGROUND

Although acute hepatitis A is usually self-limited, the clinical manifestations can vary from mild to severe liver dysfunction. However, little is known about risk factors for and outcomes of acute kidney injury (AKI) in acute hepatitis A.

OBJECTIVES

To identify the risk factors for and outcomes of AKI in acute hepatitis A.

STUDY DESIGN

We identified 396 patients with acute hepatitis A, which registered between January 2006 and June 2009 at a tertiary care university hospital. Retrospective case-control studies were conducted in order to identify risk factors for AKI.

RESULTS

Thirty patients (7.6%) developed AKI. On multivariate analysis, fulminant hepatitis, leukocytosis, and elevated CRP were independent risk factors for AKI associated with hepatitis A, and higher total bilirubin, leukocytosis, and elevated CRP were independent risk factor for AKI within nonfulminant hepatitis A. Of the 30 patients with AKI, 23 (76.7%) patients fully recovered, 2 patients maintained hemodialysis after hospital discharge and 5 patients died due to hepatic failure without recovery from AKI. Among 20 patients with AKI in nonfulminant subgroup, 19 patients (95%) recovered without hemodialysis.

CONCLUSIONS

AKI is not a rare complication of acute hepatitis A and severity of hepatitis and hepatic injury influence the development of AKI in acute hepatitis A.

What factors determine the severity of hepatitis A-related acute liver failure?

The reason(s) that hepatitis A virus (HAV) infection may progress infrequently to acute liver failure are poorly understood. We examined host and viral factors in 29 consecutive adult patients with HAV-associated acute liver failure enrolled at 10 sites participating in the US ALF Study Group. Eighteen of twenty-four acute liver failure sera were PCR positive while six had no detectable virus. HAV genotype was determined using phylogenetic analysis and the full-length genome sequences of the HAV from a cute liver failure sera were compared to those from self-limited acute HAV cases selected from the CDC database. We found that rates of nucleotide substitution did not vary significantly between the liver failure and non-liver failure cases and there was no significant variation in amino acid sequences between the two groups. Four of 18 HAV isolates were sub-genotype IB, acquired from the same study site over a 3.5-year period. Sub-genotype IB was found more frequently among acute liver failure cases compared to the non-liver failure cases (chi-square test, P < 0.01). At another centre, a mother and her son presented with HAV and liver failure within 1 month of each other. Predictors of spontaneous survival included detectable serum HAV RNA, while age, gender, HAV genotype and nucleotide substitutions were not associated with outcome. The more frequent appearance of rapid viral clearance and its association with poor outcomes in acute liver failure as well as the finding of familial cases imply a possible host genetic predisposition that contributes to a fulminant course. Recurrent cases of the rare sub-genotype IB over several years at a single centre imply a community reservoir of infection and possible increased pathogenicity of certain infrequent viral genotypes.

Scientific Opinion on an update on the present knowledge on the occurrence and control of foodborne viruses

A review of the biology, epidemiology, diagnosis and public health importance of foodborne viruses was performed. Data needs to support a risk assessment were also identified. In addition possible control options and their anticipated impact to prevent or reduce the number of foodborne viral human infections were identified, including the scientific reasons for and against the establishment of food safety criteria and process hygiene criteria for viruses for certain food categories. Food may be contaminated by virus during all stages of the food supply chain, and transmission can occur by consumption of food contaminated during the production process (primary production, or during further processing), or contaminated by infected food handlers. Transmission of zoonotic viruses (e.g. HEV) can also occur by consumption of products of animal origin. Viruses do not multiply in foods, but may persist for extended periods of time as infectious particles in the environment, or in foods. At the EU-level it is unknown how much viral disease can be attributed to foodborne spread. The relative contribution of different sources (shellfish, fresh produce, food handler including asymptomatic shedders, food handling environment) to foodborne illness has not been determined. The Panel recommends focusing controls on preventive measures to avoid viral contamination rather than trying to remove/inactivate these viruses from food. Also, it is recommended to introduce a microbiological criteria for viruses in bivalve molluscs, unless they are labelled "to be cooked before consumption". The criteria could be used by food business operators to validate their control options. Furthermore, it is recommended to refine the regulatory standards and monitoring approaches in order to improve public health protection. Introduction of virus microbiological criteria for classification of bivalve molluscs production areas should be considered. A virus monitoring programme for compliance with these criteria should be risk based according to the findings of a sanitary survey.

Genus-specific substitution rate variability among picornaviruses

Picornaviruses have some of the highest nucleotide substitution rates among viruses, but there have been no comparisons of evolutionary rates within this broad family. We combined our own Bayesian coalescent analyses of VP1 regions from four picornaviruses with 22 published VP1 rates to produce the first within-family meta-analysis of viral evolutionary rates. Similarly, we compared our rate estimates for the RNA polymerase 3D(pol) gene from five viruses to four published 3D(pol) rates. Both a structural and a nonstructural gene show that enteroviruses are evolving, on average, a half order of magnitude faster than members of other genera within the Picornaviridae family.

Genotyping of acute hepatitis a virus isolates from China, 2003-2008

Hepatitis A virus (HAV) is usually transmitted by an oral-fecal route and is prevalent not only in developing countries but also in developed countries. In the present study, the phylogenetic characterization of the VP1/2A junction region (321 nucleotides) of China HAV isolates was examined. Anti-HAV IgM-positive serum samples were collected from 8 provinces, including 20 cities or counties in China from 2003 to 2008; 337 isolates from 406 HAV patients' serum samples were amplified by RT-PCR, sequenced at the VP1/2A junction region and aligned with the published sequences from GenBank to establish phylogenetic analysis. All China HAV isolates in this study belonged to genotype I, with 98.8% (333/337) of samples clustering in sub-genotype IA and 1.2% (4/337) in sub-genotype IB. In addition, sub-genotype IA isolates clustered into four groups (92.7-100% nucleotide identity), and the samples collected from all China HAV isolates in this investigation showed 87.5-100% nucleotide identity, but the amino acids in this region were more conserved (95.2-100% identity). Few unique amino acid changes could be deduced (VP1-253: Glu → Gly; 2A-34: Pro → Ala; 2A-33: Leu → Phe). Genetically identical or similar HAV strains existed in some investigated areas in China during different years, suggesting that an indigenous strain has been circulating in those regions. This report provides new data on the genetic relatedness and molecular epidemiology of HAV isolates from China as well as the distribution of sub-genotype IA and IB in this part of the world.

Hepatitis A viral load in relation to severity of the infection

A correlation between hepatitis A virus (HAV) genomes and the clinical severity of hepatitis A has not been established. The viral load in sera of hepatitis A patients was examined to determine the possible association between hepatitis A severity and HAV replication. One hundred sixty-four serum samples from 91 Japanese patients with sporadic hepatitis A, comprising 11 patients with fulminant hepatitis, 10 with severe acute hepatitis, and 70 with self-limited acute hepatitis, were tested for HAV RNA. The sera included 83 serial samples from 20 patients. Viral load was measured by real-time RT-PCR. The detection rates of HAV RNA from fulminant, severe acute, and acute hepatitis were 10/11 (91%), 10/10 (100%), and 55/70 (79%), respectively. Mean values of HAV RNA at admission were 3.48 ± 1.30 logcopies/ml in fulminant, 4.19 ± 1.03 in severe acute, and 2.65 ± 1.64 in acute hepatitis. Patients with severe infection such as fulminant hepatitis and severe acute hepatitis had higher initial viral load than patients with less severe infection (P < 0.001). Viremia persisted for 14.2 ± 5.8 days in patients with severe infection and 21.4 ± 10.6 days in those with acute hepatitis after clinical onset (P = 0.19). HAV RNA was detectable quantitatively in the majority of the sera of hepatitis A cases during the early convalescent phase by real-time PCR. Higher initial viral replication was found in severely infected patients. An excessive host immune response might follow, reducing the viral load rapidly as a result of the destruction of large numbers of HAV-infected hepatocytes, and in turn severe disease might be induced.

[Genetic diversity of a rare hepatitis A virus genotype]

PURPOSE OF THE STUDY

Very few is known on genotype II hepatitis A virus (HAV) since it is rarely isolated. From 2002 to 2007, the French observatory of HAV identified six sub-genotype IIA strains of which one from a patient having travelled to West Africa. To investigate the possible African origin of sub-genotype IIA, we determined its prevalence among French travellers in 2008 and characterised its genetic variability.

PATIENTS AND METHODS

The 2008 mandatory notification records were screened for travel to Africa. Viral genotype was determined on the nucleotide sequencing of the VP1/2A junction region. The P1 region coding for capsid proteins was used to compare the genetic diversity of IIA isolates to those of other genotypes.

RESULTS

In 2008, five out of 54 patients returning from West Africa were infected by IIA strains and an additional "autochthonous" case was identified. Two more African cases were identified in 2009. A total of 14 IIA isolates (eight African and six "autochthonous") were analysed. Nucleotide and amino-acid variability of IIA sequences was lower than that of the other genotypes. Phylogenetic analysis revealed the clustering of two "autochthonous" cases with African isolates whereas the other ones belonged to a different lineage.

CONCLUSION

Most IIA strains isolated in France are imported by travellers returning from West Africa. However, the unexplained contamination mode of some "autochthonous" cases suggests another geographical origin to discover or a French reservoir to explore.

Nucleotide variability and translation efficiency of the 5' untranslated region of hepatitis A virus: update from clinical isolates associated with mild and severe hepatitis

Mutations in the internal ribosome entry site (IRES) of hepatitis A virus (HAV) have been associated with enhanced in vitro replication and viral attenuation in animal models. To address the possible role of IRES variability in clinical presentation, IRES sequences were obtained from HAV isolates associated with benign (n = 8) or severe (n = 4) hepatitis. IRES activity was assessed using a bicistronic dual-luciferase expression system in adenocarcinoma (HeLa) and hepatoma (HuH7) cell lines. Activity was higher in HuH7 than in HeLa cells, except for an infrequently isolated genotype IIA strain. Though globally low, significant variation in IRES-dependent translation efficiency was observed between field isolates, reflecting the low but significant genetic variability of this region (94.2% +/- 0.5% nucleotide identity). No mutation was exclusive of benign or severe hepatitis, and variations in IRES activity were not associated with a clinical phenotype, indirectly supporting the preponderance of host factors in determining the clinical presentation.

Epidemiology and genetic characterization of hepatitis A virus genotype IIA

Three hepatitis A virus (HAV) genotypes, I, II, and III, divided into subtypes A and B, infect humans. Genotype I is the most frequently reported, while genotype II is hardly ever isolated, and its genetic diversity is unknown. From 2002 to 2007, a French epidemiological survey of HAV identified 6 IIA isolates, mostly from patients who did not travel abroad. The possible African origin of IIA strains was investigated by screening the 2008 mandatory notification records of HAV infection: 171 HAV strains from travelers to West Africa and Morocco were identified. Genotyping was performed by sequencing of the VP1/2A junction in 68 available sera. Entire P1 and 5' untranslated regions of IIA strains were compared to reference sequences of other genotypes. The screening retrieved 5 imported IIA isolates. An additional autochthonous case and 2 more African cases were identified in 2008 and 2009, respectively. A total of 14 IIA isolates (8 African and 6 autochthonous) were analyzed. IIA sequences presented lower nucleotide and amino acid variability than other genotypes. The highest variability was observed in the N-terminal region of VP1, while for other genotypes the highest variability was observed at the VP1/2A junction. Phylogenetic analysis identified 2 clusters, one gathering all African and two autochthonous cases and a second including only autochthonous isolates. In conclusion, most IIA strains isolated in France are imported by travelers returning from West Africa. However, the unexplained contamination mode of autochthonous cases suggests another, still to be discovered geographical origin or a French reservoir to be explored.

Clinical implications of hepatitis A virus ribonucleic acid detection and genotyping in acute liver failure in children in Argentina

OBJECTIVES

To investigate the detection of hepatitis A virus ribonucleic acid in patients with acute liver failure and to assess if the results have any clinical implications for the evolution of acute liver failure in children. Hepatitis A infection, a vaccine-preventable disease, is an important cause of acute liver failure in children in Argentina. Universal vaccination in 1-yr-old children was implemented in June 2005.

DESIGN

Observational study in which patients were divided into Group 1 consisting of positive hepatitis A virus ribonucleic acid and Group 2 consisting of negative hepatitis A virus ribonucleic acid.

SETTING

Pediatric intensive care unit in National Pediatric Hospital "Dr. J. P. Garrahan," Buenos Aires, Argentina.

PATIENTS

Thirty-three patients with the diagnosis of acute liver failure secondary to hepatitis A virus infection and admitted to the Garrahan Pediatric Hospital between September 2003 and September 2005 were enrolled in the study. Twenty of these children were admitted to the pediatric intensive care unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Samples for total ribonucleic acid detection and genotyping were obtained from serum and/or stools on admission. We found positive hepatitis A virus ribonucleic acid in 13 patients and negative hepatitis A virus ribonucleic acid in 20 patients. The following clinical variables were evaluated: time of evolution, hospital stay, admission to the pediatric intensive care unit, pediatric intensive care unit stay, time on mechanical ventilation, criteria for orthotopic liver transplantation, and mortality. Characterization of the isolates did not reveal differences related to genotype; all cases were IA. No statistical significance was found as to the variables. However, positive hepatitis A virus ribonucleic acid showed lower percentages of pediatric intensive care unit admissions, criteria for orthotopic liver transplantation, number of orthotopic liver transplantation, and mortality than the group of patients with negative hepatitis A virus ribonucleic acid.

CONCLUSIONS

Hepatitis A virus genotyping studies did not show any particularities, all cases were IA and, thus, apparent associations between genotype and the clinical presentation of acute liver failure could not be found.

Phylogenetic analysis of hepatitis A virus in sera from patients with hepatitis A of various severities

BACKGROUND

We analysed the association of the 5' nontranslated region (5'NTR), nonstructural proteins 2B and 2C of the hepatitis A virus (HAV) genome, whose mutations have previously been shown to be important for enhanced replication in cell culture systems, in order to align all our data and examine whether genomic differences in HAV are responsible for the range of clinical severities.

METHODS

Our accumulated HAV strains of 5'NTR [nucleotide(nt) 200 and 500], entire 2B and 2C from 25 Japanese patients with sporadic hepatitis A, consisting of seven patients with fulminant hepatitis (FH), five with severe acute hepatitis (AHs) and 13 with self-limited acute hepatitis (AH), in whom the sequences of all three regions were available, were subjected to phylogenetic analysis.

RESULTS

Fulminant hepatitis patients had fewer nucleotide substitutions in 5'NTR, had a tendency to have more amino acid (aa) substitutions in 2B and had fewer aa substitutions in 2C than AH patients. Four FH and two AHs with a higher viral replication were located in the near parts of the phylogenetic trees, indicating the association between the severity of hepatitis A and genomic variations in 5'NTR, 2B and 2C of HAV.

CONCLUSIONS

Our study suggests that genetic variations in HAV not in one specific region but in 5'NTR, 2B and 2C might cooperatively influence replication of the virus, and thereby affect virulence. Viral factors should be considered and examined when discussing the mechanisms responsible for the severity of hepatitis A.

Hepatitis A outbreaks in China during 2006: application of molecular epidemiology

BACKGROUND

In China, hepatitis is a huge public health problem. Outbreaks of hepatitis A are the most frequent cause of acute hepatitis, and to date, few epidemiologic investigations or molecular surveillance studies have been performed.

MATERIALS AND METHODS

In 2006, two major outbreaks of hepatitis A occurred, one in Guigang City, southern China, and the other in Hetian City, northwestern China. Field and molecular epidemiologic investigations were conducted.

RESULTS

In Guigang, a single outbreak occurred in a school; 35 patients and 25 asymptomatic individuals were infected with 1 strain of hepatitis A virus (HAV). A case-control study showed that contaminated water was the likely transmission source. In Hetian, the epidemic of hepatitis A consisted of sporadic, small outbreaks involving as many as 20 wild HAV strains. A molecular epidemiology approach allowed us to identify two groups infected by individual HAV strains. Further fieldwork and a case-control study showed that ice cream was the suspected transmission source in one group. Our molecular epidemiology study showed that genetic variability between the HAV strains isolated from Guigang and Hetian and previously reported HAV strains was at least 4.3%.

CONCLUSION

Contaminated water and suspected ice cream were associated with outbreaks of hepatitis A. Viral genetic analysis may advance field investigations in complex situations.

Detection of hepatitis A virus RNA from children patients with acute and fulminant hepatitis of unknown etiology in Vietnam: Genomic characterization of Vietnamese HAV strain

BACKGROUND

Although it is thought that Vietnam is a high endemic region of hepatitis A virus (HAV) infection, there is no report on genomic characterization of HAV spread in Vietnam. The purpose of the present paper was therefore to identify various virus infections from 33 children with acute or fulminant hepatitis of unknown etiology admitted to Children's Hospital No.1 in Ho Chi Minh City, Vietnam.

METHODS

Anti-HAV IgM and IgG were assayed by ELISA. Viral RNA and DNA were determined by PCR method. HAV genes isolated by PCR were sequenced and characterized by phylogenetic analysis.

RESULTS

Anti-HAV IgM was detected in 18 of 26 acute hepatitis (69.2%) and one of seven (14.3%) fulminant hepatitis patients. Furthermore, HAV-RNA in serum was identified in five of 26 acute (19.2%) and two of seven (28.6%) fulminant hepatitis patients, respectively, on nested reverse transcription-polymerase chain reaction. Among the seven HAV-RNA-positive patients tested, two (28.6%) were negative for anti-HAV IgM. We also obtained seven isolates containing the HAV genome with the viral protein 1 (VP1) region sequence. All Vietnamese HAV isolates formed a cluster and belonged to genotype IA according to phylogenetic analysis based on the short sequences of VP1-2A junction region.

CONCLUSION

HAV is an important agent with regard to fulminant hepatitis among children in Vietnam. To the authors' knowledge this is the first report on Vietnamese HAV strain confirmed on sequencing.

Experiences with acute kidney injury complicating non-fulminant hepatitis A

AIM

To describe the clinical features and to identify factors related to development of acute kidney injury in acute hepatitis A patients.

METHODS

The study and control groups consisted of 21 and 425 patients who did or did not develop acute kidney injury, respectively, after acute hepatitis A from January 1997 to May 2007.

RESULTS

There were 13 men and eight women; their mean age at diagnosis was 28.8 +/- 8.2 years in the study group. Peak values for renal and liver function impairment consisted of a median serum creatinine of 4.6 mg/dL (range, 1.5-15.3 mg/dL) on day 6 (range, days 1-20) and a median total bilirubin of 10.7 mg/dL (range, 2.6-57.5 mg/dL) on day 8 (range, day 1-19). Serum creatinine concentrations returned to baseline level by a median of 16 days and total bilirubin levels returned to normal by a median of 62 days. Six of 21 (29%) patient underwent haemodialysis. Renal biopsies performed in two patients showed acute tubular necrosis and interstitial nephritis, respectively. Logistic regression analysis showed that a lower haematocrit, the presence of coagulopathy and high C-reactive protein concentration on admission, and higher peak bilirubin value during the illness were associated with development of acute kidney injury.

CONCLUSION

Acute hepatitis A should be considered in the differential diagnosis of patients with acute kidney injury, even without fulminant hepatic failure. A lower haematocrit, the presence of coagulopathy and high C-reactive protein level at presentation, and higher peak bilirubin level during the illness were associated with development of acute kidney injury in acute hepatitis A patients.

Molecular characterization of hepatitis A virus in children with fulminant hepatic failure in Argentina

BACKGROUND

Hepatitis A infection, a vaccine-preventable disease, is an important cause of fulminant hepatic failure (FHF) in children in Argentina. Universal vaccination in 1-year-old children was implemented in June 2005. The limited studies about the correlation between the characteristics of the hepatitis A virus (HAV) and FHF have been carried out in adults.

METHODS

Samples from 41 children with FHF were studied from September 2003 to January 2006 and HAV RNA was detected, sequenced and analysed in the 5' non-coding region and VP1/2A region.

RESULTS

Eighteen HAV strains were characterized and found to be different at the nucleotide level from the self-limited acute infection strains that have been circulating in Argentina with no temporal or geographical pattern. They did not form a genetic cluster, but some of them were identical in the largest fragment characterized and some of them seemed to be more closely related in time and/or geographically.

CONCLUSION

Our results suggest that viral factors could be involved in the severity of the clinical presentation of HAV infection in children in Argentina.

Initial thrombocytopenia as a simple, valuable predictor for clinical manifestation in acute hepatitis A

OBJECTIVE

Although acute hepatitis A (AH-A) is usually self-limited, the clinical manifestations can vary from mild to severe liver dysfunction. However, little is known about the simple, valuable predictors for clinical manifestation in AH-A. The objective of this study was to identify the simple clinical predictors for severe liver dysfunction and its clinical course.

MATERIAL AND METHODS

A total of 162 IgM anti-hepatitis A virus (HAV) positive patients were enrolled in the study. Severe AH-A was defined as a prothrombin time <40% of control activity. Various liver-unrelated and liver-related parameters at presentation were compared separately between the severe AH-A group and the non-severe group.

RESULTS

Mean age (+/-SD) was 27.5 (+/-7.1) years and the proportion of males was 54% (88/162). Fourteen patients (8.7%) experienced severe AH-A. Of the liver-unrelated parameters, leukopenia (<4000/microl), thrombocytopenia (<150,000/microl), and high serum C-reactive protein levels (>8 mg/l) at presentation were significant predictors for severe AH-A in a univariate analysis (p<0.05). On multivariate analysis, only thrombocytopenia was an independent predictor for severe AH-A (odds ratio (OR) 5.562, 95% confidence interval (CI) 1.153-26.834, p=0.033). Of the liver-related parameters, there were no independent predictors, as shown by multivariate analysis. The thrombocytopenia group (33%, 54/162) not only had a longer recovery time (28 days (range, 14-140) versus 37 days (20-128), p<0.001), but also more frequent complications (OR 4.632, 95% CI 1.886-11.372, p=0.001) than the non-thrombocytopenia group.

CONCLUSIONS

Initial thrombocytopenia may be a simple, valuable predictor for severity and clinical course in AH-A.

Silencing of hepatitis A virus infection by small interfering RNAs

Infection by hepatitis A virus (HAV) can cause acute hepatitis and, rarely, fulminant liver failure, in particular in patients chronically infected with hepatitis C virus. Based on our previous observation that small interfering RNAs (siRNAs) can silence translation and replication of the firefly luciferase-encoding HAV replicon, we now exploited this technology to demonstrate the effect of siRNAs on viral infection in Huh-7 cells. Freshly and persistently infected cells were transfected with siRNAs targeting various sites in the HAV nonstructural genes. Compared to a single application, consecutive siRNA transfections targeting multiple sequences in the viral genome resulted in a more efficient and sustained silencing effect than a single transfection. In most instances, multiple applications of a single siRNA led to the emergence of viral escape mutants with mutated target sites that rendered these genomes resistant to RNA interference (RNAi). Efficient and sustained suppression of the viral infectivity was achieved after consecutive applications of an siRNA targeting a computer-predicted hairpin structure. This siRNA holds promise as a therapeutic tool for severe courses of HAV infection. In addition, the results provide new insight into the structural bases for sequence-specific RNAi.

Analysis of hepatitis A virus protein 2B in sera of hepatitis A of various severities

BACKGROUND

In our recent study of the full-length hepatitis A virus (HAV) genome from some patients with fulminant hepatitis and acute hepatitis, possible associations were suggested between the severity of hepatitis A and the amino acid substitutions in the nonstructural protein 2B. We therefore analyzed HAV 2B from many patients with various clinical disease severities.

METHODS

Serum samples from 30 Japanese patients with sporadic hepatitis A from five widely separated regions of Japan, comprising nine patients with fulminant hepatitis (FH), six with severe acute hepatitis (AHs), and 15 with acute hepatitis (AH), were examined for HAV RNA. The entire sequences of HAV 2B were analyzed.

RESULTS

Compared with the sequence of the wild-type HAV strain GBM, nucleotide sequences of 2B had homology of 94.5 +/- 1.0% in FH, 95.2 +/- 1.2% in AHs, and 95.1 +/- 1.8% in AH. Deduced amino acid sequences had homology of 97.5 +/- 2.1% in FH, 97.9 +/- 2.4% in AHs, and 98.5 +/- 1.3% in AH. Differences were not statistically significant among the three groups. The average number of amino acid mutations between amino acids 100 and 200 was 5.0 +/- 5.2 per case in FH, 4.0 +/- 6.0 in AHs, and 1.9 +/- 2.9 in AH. The differences between FH and AH, AHs and AH, and between severe cases (FH and AHs) and nonsevere cases (AH) were not statistically significant (P = 0.13, P = 0.45, and P = 0.10, respectively).

CONCLUSIONS

There were no obvious differences in the sequences among FH, AHs, and AH throughout the 2B region, but there seemed to be more mutations in the strains obtained from FH and AHs patients than in those obtained from AH patients in the central part of HAV 2B.

Genetic variability of hepatitis A virus strain HAF-203 isolated in Brazil and expression of the VP1 gene in Escherichia coli

The hepatitis A virus (HAV) HAF-203 strain was isolated from an acute case of HAV infection. The primary isolation of HAF-203 in Brazil and its adaptation to the FRhK-4 cell lineage allowed the production of large amounts of viral particles enabling molecular characterization of the first HAV isolate in Brazil. The aim of our study was to determine the nucleotide sequence of the HAF-203 strain genome, compare it to other HAV genomes and highlight its genetic variability. The complete nucleotide sequence of the HAF-203 strain (7472 nucleotides) was compared to those obtained earlier by others for other HAV isolates. These analyses revealed 19 HAF-specific nucleotide sequence differences with 10 amino acid substitutions. Most of the non-conservative changes were located at VP1, 2C, and 3D genes, but the 3B region was the most variable. The availability of HAF-203 complementary DNA was useful for the production of the recombinant VP1 protein, which is a major determinant of viral infectivity. This recombinant protein was shown by enzyme-linked immunoassay and blotting, to be immunogenic and resemble the native protein, therefore suggesting its value as a reagent for incorporation into diagnostic tests.

Acute Hepatitis with Severe Cholestasis and Prolonged Clinical Course Due to Hepatitis A Virus Ia and Ib Coinfection

BACKGROUND

Acute viral hepatitis due to hepatitis A virus is a self-limited illness that infrequently has a severe clinical course.

METHODS

We analyzed the virological characteristics of acute hepatitis A in a patient with a severe clinical presentation (peak total and conjugated bilirubin levels, 65.5 mg/dL and 40.1 mg/dL, respectively) and a course of disease that lasted 7 months.

RESULTS

Hepatitis A virus sequencing revealed coinfection with 2 subgenotypes of hepatitis A virus (Ia and Ib) as etiological factors of the illness.

CONCLUSIONS

Hepatitis A virus Ia and Ib coinfection may have accounted for the prolonged and severe course of illness.

Genetic analysis of HAV strains in Tunisia reveals two new antigenic variants

To evaluate the genetic variability of hepatitis A virus (HAV) isolates in Tunisia, serum samples were collected from 99 patients in different Tunisian areas in 2003 containing 92 cases with acute hepatitis, five with severe acute hepatitis and two with fulminant hepatitis. The entire VP1 gene was amplified and sequenced. Sequences were then aligned and a phylogenetic analysis was performed. Additionally, the amino acid (aa) sequence of the VP1 was determined. The analysis of Tunisian HAV isolates revealed that all the isolates were sub-genotype IA with 96.4%-99.8% of identity and showed the emergence of two novel antigenic variants. The Tun31-03 antigenic variant, with a 38 aa deletion containing Met156, Val171, Leu174 and Ala176 and located between 150 and 187 aa of the VP1 protein where neutralization escape mutations, was found. The second antigenic variant, Tun36-03, was isolated from a patient with fulminant hepatitis and presented a substitution of Thr by Pro at position 10 of the VP1 protein. This amino acid is located in a peptide presenting an antigenically reactive epitope of the VP1 protein. This substitution has never been described previously.

Genetic variability and evolution of hepatitis E virus

Hepatitis E virus (HEV) is the sole member of the genus Hepevirus in the family Hepeviridae. HEV is transmitted primarily by the fecal-oral route, and water-borne epidemics are characteristic of hepatitis E in many developing countries in Asia, Africa and Latin America where sanitation conditions are suboptimal. Accumulating lines of evidence indicate that HEV-associated hepatitis also occurs domestically among individuals in industrialized countries, that there are animal reservoirs of HEV such as domestic pigs and wild boars, and that hepatitis E is a zoonosis. Based on the extensive genomic variability among HEV isolates, HEV sequences have been classified into four genotypes: genotype 1 consists of epidemic strains in developing countries in Asia and Africa; genotype 2 has been described in Mexico and several African countries; genotype 3 HEV is widely distributed and has been isolated from sporadic cases of acute hepatitis E and/or domestic pigs in many countries in the world, except for countries in Africa; and genotype 4 contains strains isolated from humans and/or domestic pigs exclusively in Asian countries. This paper reviews current knowledge on the genomic variability, geographic distribution and zoonotic aspects of HEV as well as the clinical significance of genotype and evolution of HEV.

Cocirculation of and coinfections with hepatitis A virus subgenotypes IIIA and IB in patients from Pune, western India

AIM

During the 1990s, a changing pattern of epidemiology of hepatitis A was reported in different populations of India. The present study was undertaken to investigate the molecular epidemiology of hepatitis A virus (HAV) strains over a period of 10 years.

METHODS

Stool/serum samples were collected from hepatitis A patients clinically presenting acute viral hepatitis and hepatic encephalopathy. Reverse transcriptase polymerase chain reaction (RT-PCR) was performed to detect HAV-RNA. HAV genomes were examined by sequencing PCR products of VP1/2A junction (168 bp) and RNA polymerase (116 bp) regions.

RESULTS

Subgenotype IIIA and IB were detected in 74.2% and 9.7% of specimens, respectively, while 16.1% of patients had mixed infections. Sewage samples also showed presence of both IIIA (9/10) and IB (1/10) subgenotypes. RNA polymerase region showed two clusters constituting 51.6% and 19.4% strains closer to Nor21 and HM175 strains, respectively, in clinical specimens. Three isolates appeared as discordant subgenotypes in VP1/2A and RNA polymerase regions.

CONCLUSION

The data revealed cocirculation of and coinfection with subgenotypes IIIA and IB, with predominance of IIIA and genetic heterogeneity of HAV strains in western India.

Analysis of the full-length genome of genotype 4 hepatitis E virus isolates from patients with fulminant or acute self-limited hepatitis E

It was suggested that hepatitis E virus (HEV) genotype 4 is associated more closely with the severity of hepatitis E than genotype 3, although the virological basis remains unknown. The aim of this study was to examine whether genomic differences among genotype 4 HEVs are responsible for the development of fulminant hepatitis. Full-length sequences of genotype 4 HEVs from three patients with fulminant hepatitis and six patients with acute self-limited hepatitis were determined. The sequences were analyzed with those of 13 genotype 4 HEV isolates whose entire nucleotide sequence is known. Analysis of 22 full-length sequences (fulminant hepatitis, 5; acute hepatitis, 17) revealed that C at nt 1816 and U at nt 3148 (U3148), both of which do not change the amino acid sequences, were significantly associated with fulminant hepatitis (P = 0.0489, respectively). When partial nucleotide sequences containing nt 1816 or nt 3148 were determined in 16 additional HEV isolates of genotype 4, a closer association between U3148 and fulminant hepatitis (P = 0.0018) was observed. The comparison of 86 HEV isolates of all four genotypes showed that U3148 had a stronger association with fulminant hepatitis than other nucleotides at nt 3148 (P = 0.0006). Patients infected with HEV with U3148 had a significantly lower value of the lowest prothrombin activity (P = 0.0293). Nt 3148 is located within the RNA helicase domain, and 22-nt sequence including nt 3148 was well conserved among all genotypes. A silent substitution of U3148 in HEV may be associated with the development of fulminant hepatitis. Further studies are needed to clarify the underlying mechanism.

Diagnosis of hepatitis a virus infection: a molecular approach

Current serologic tests provide the foundation for diagnosis of hepatitis A and hepatitis A virus (HAV) infection. Recent advances in methods to identify and characterize nucleic acid markers of viral infections have provided the foundation for the field of molecular epidemiology and increased our knowledge of the molecular biology and epidemiology of HAV. Although HAV is primarily shed in feces, there is a strong viremic phase during infection which has allowed easy access to virus isolates and the use of molecular markers to determine their genetic relatedness. Molecular epidemiologic studies have provided new information on the types and extent of HAV infection and transmission in the United States. In addition, these new diagnostic methods have provided tools for the rapid detection of food-borne HAV transmission and identification of the potential source of the food contamination.