Genetic, antigenic and biological differences between strains of hepatitis A virus

A new genotype of hepatitis A virus causing transient liver enzyme elevations in Mauritius-origin laboratory-housed Macaca fascicularis

Hepatitis A virus (HAV) infects humans and nonhuman primates, typically causing an acute self-limited illness. Three HAV genotypes have been described so far for humans, and three genotypes have been described for nonhuman primates. We observed transiently elevated liver enzymes in Mauritius-origin laboratory-housed macaques in Germany and were not able to demonstrate an etiology including HAV by serology and polymerase chain reaction (PCR). HAV is a rare pathogen in cynomolgus macaques, and since all employees were routinely vaccinated against HAV, it was not a part of the routine vaccination and screening program. A deep sequencing approach identified a new HAV genotype (referred to as Simian_HAV_Macaca/Germany/Mue-1/2022) in blood samples from affected animals. This HAV was demonstrated by reverse transcription PCR in blood and liver and by in situ hybridization in liver, gall bladder, and septal ducts. A commercial vaccine was used to protect animals from liver enzyme elevation. The newly identified simian HAV genotype demonstrates 80% nucleotide sequence identity to other simian and human HAV genotypes. There was deeper divergence between Simian_HAV_Macaca/Germany/Mue-1/2022 and other previously described HAVs, including both human and simian viruses. In situ hybridization indicated persistence in the biliary epithelium up to 3 months after liver enzymes were elevated. Vaccination using a commercial vaccine against human HAV prevented reoccurrence of liver enzyme elevations. Because available assays for HAV did not detect this new HAV genotype, knowledge of its existence may ameliorate potential significant epidemiological and research implications in laboratories globally.

Epidemiological characteristics of acute hepatitis A, 2013-2016: a cross-sectional study in Morocco

BACKGROUND

Hepatitis A virus (HAV) is the common cause of acute hepatitis worldwide. Indeed, hepatitis A is endemic in developing countries such in Morocco and most residents are exposed in childhood. The characterisation of circulating strains of HAV remains crucial to understand the virological evolution and geo-temporal characteristics, which are essential for controlling infections and outbreaks. The purpose of the current study was the detection and characterisation of HAV strains circulating in Morocco by performing serological test, RT-PCR, sequencing and phylogenetic analysis.

METHODS

In this cross-sectional study, 618 suspected acute hepatitis cases were examined by Architect HAV abIgM. Of the 162 positives, 64 underwent RNA extraction. None of the suspected cases was immune to HAV and none of them had received a blood transfusion. Samples found positive by RT-PCR using primers targeting the VP1/VP2A junction and the VP1/VP3 capsid region of HAV were subjected to sequencing and phylogenetic analyses.

RESULTS

HAV Acute infection rate was 26.2% [95% CI, 22.8-29.9], while viraemia reached 45% (29/64) after amplification of the VP3/VP1 region. Phylogenetic analysis of the VP1/2A segment revealed the presence of sub-genotypes IA and IB. Eighty-seven percent of the strains belonged to the subgenotype IA, while twelve percent to IB subgenotype.

CONCLUSION

This first molecular study of acute hepatitis A in Morocco provided information about genetic diversity of HAV, revealing the co-circulating of only two subgenotypes (IA and IB). Notably, subgenotype IA was found to be the predominant subgenotype in Morocco.

Development of enhanced primer sets for detection of Norovirus and Hepatitis A in food samples from Guayaquil (Ecuador) by reverse transcriptase-heminested PCR

Norovirus (NV) is an infectious biological agent that causes gastrointestinal problems of the original nonbacterial appearance of foodborne illnesses. The genotype of NV responsible for the most frequent NV disease outbreaks is GII, accounting for 60–80% of the cases. Moreover, original and new NV variants are continuously emerging, concurrent with the recent global increase in NV infections. Hepatitis A virus (HAV) is another foodborne pathogen frequently implicated in acute gastroenteritis cases around the world. The virus is transmitted among humans via the fecal-oral route, and infection by HAV causes the most severe form of viral illness acquired from foods. In this study, we implemented primer sets to detect NV genotypes I and II. We also developed primer sets for the detection of HAV. The primers were used in a heminested reverse transcriptase PCR (hnRT-PCR) protocol that was rapid and sensitive for detecting NVG1, NVGII and HAV virus in food. The hnRT-PCR was applied successfully to strawberries and spinach obtained from a local fresh-food market, where we could see NVGI, NVGII and HAV. Keywords: Norovirus1; Hepatitis A2; gastroenteritis3; genotypes4; NVG15; NVGII6; hnRT-PCR7.

Inactivation of Foodborne Viruses by UV Light: A Review

Viruses on some foods can be inactivated by exposure to ultraviolet (UV) light. This green technology has little impact on product quality and, thus, could be used to increase food safety. While its bactericidal effect has been studied extensively, little is known about the viricidal effect of UV on foods. The mechanism of viral inactivation by UV results mainly from an alteration of the genetic material (DNA or RNA) within the viral capsid and, to a lesser extent, by modifying major and minor viral proteins of the capsid. In this review, we examine the potential of UV treatment as a means of inactivating viruses on food processing surfaces and different foods. The most common foodborne viruses and their laboratory surrogates; further explanation on the inactivation mechanism and its efficacy in water, liquid foods, meat products, fruits, and vegetables; and the prospects for the commercial application of this technology are discussed. Lastly, we describe UV’s limitations and legislation surrounding its use. Based on our review of the literature, viral inactivation in water seems to be particularly effective. While consistent inactivation through turbid liquid food or the entire surface of irregular food matrices is more challenging, some treatments on different food matrices seem promising.

A new assay for quantitative detection of hepatitis A virus

Hepatitis A virus (HAV) is mainly transmitted via contaminated food or water or through person-to-person contact. Here, we describe development and evaluation of a reverse transcription droplet digital PCR (RT-ddPCR) and reverse transcription real-time PCR (RT-qPCR) assay for detection of HAV in food and clinical specimens. The assay was evaluated by assessing limit of detection, precision, matrix effects, sensitivity and quantitative agreement. The 95 % limit of detection (LOD95 %) was 10 % higher for RT-ddPCR than for RT-qPCR. A Bayesian model was used to estimate precision on different target concentrations. From this, we found that RT-ddPCR had somewhat greater precision than RT-qPCR within runs and markedly greater precision between runs. By analysing serum from naturally infected persons and a naturally contaminated food sample, we found that the two methods agreed well in quantification and had comparable sensitivities. Tests with artificially contaminated food samples revealed that neither RT-ddPCR nor RT-qPCR was severely inhibited by presence of oysters, raspberries, blueberries or leafy-green vegetables. For this assay, we conclude that RT-qPCR should be considered if rapid, qualitative detection is the main interest and that RT-ddPCR should be considered if precise quantification is the main interest. The high precision of RT-ddPCR allows for detection of small changes in viral concentration over time, which has direct implications for both food control and clinical studies.

Improving preparedness to respond to cross-border hepatitis A outbreaks in the European Union/European Economic Area: towards comparable sequencing of hepatitis A virus

IntroductionSequence-based typing of hepatitis A virus (HAV) is important for outbreak detection, investigation and surveillance. In 2013, sequencing was central to resolving a large European Union (EU)-wide outbreak related to frozen berries. However, as the sequenced HAV genome regions were only partly comparable between countries, results were not always conclusive.AimThe objective was to gather information on HAV surveillance and sequencing in EU/European Economic Area (EEA) countries to find ways to harmonise their procedures, for improvement of cross-border outbreak responses.MethodsIn 2014, the European Centre for Disease Prevention and Control (ECDC) conducted a survey on HAV surveillance practices in EU/EEA countries. The survey enquired whether a referral system for confirming primary diagnostics of hepatitis A existed as well as a central collection/storage of hepatitis A cases' samples for typing. Questions on HAV sequencing procedures were also asked. Based on the results, an expert consultation proposed harmonised procedures for cross-border outbreak response, in particular regarding sequencing. In 2016, a follow-up survey assessed uptake of suggested methods.ResultsOf 31 EU/EEA countries, 23 (2014) and 27 (2016) participated. Numbers of countries with central collection and storage of HAV positive samples and of those performing sequencing increased from 12 to 15 and 12 to 14 respectively in 2016, with all countries typing an overlapping fragment of 218 nt. However, variation existed in the sequenced genomic regions and their lengths.ConclusionsWhile HAV sequences in EU/EEA countries are comparable for surveillance, collaboration in sharing and comparing these can be further strengthened.

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.

Main Groups of Microorganisms of Relevance for Food Safety and Stability

Microbiology is important to food safety, production, processing, preservation, and storage. Microbes such as bacteria, molds, and yeasts are employed for the foods production and food ingredients such as production of wine, beer, bakery, and dairy products. On the other hand, the growth and contamination of spoilage and pathogenic microorganisms is considered as one of the main causes to loss of foodstuff nowadays. Although technology, hygienic strategies, and traceability are important factors to prevent and delay microbial growth and contamination, food remains susceptible to spoilage and activity of pathogen microorganisms. Food loss by either spoilage or contaminated food affects food industry and consumers leading to economic losses and increased hospitalization costs. This chapter focuses on general aspects, characteristics, and importance of main microorganisms (bacteria, yeasts, molds, virus, and parasites) involved in food spoilage or contamination: known and recently discovered species; defects and alterations in foodstuff; most common food associated with each foodborne disease; resistance to thermal processing; occurrence in different countries; outbreaks; and associated symptoms.

Clinical Features and Transmission Pattern of Hepatitis A: An Experience from a Hepatitis A Outbreak Caused by Two Cocirculating Genotypes in Sri Lanka

Sri Lanka is one of the intermediate-endemic areas for hepatitis A virus (HAV), and concerns exist about the increasing HAV-susceptible population. In fact, Sri Lanka recorded a large hepatitis outbreak, possibly hepatitis A, around the end of the Sri Lankan war. It included more than 14,000 patients consisting of local residents, internally displaced personnel, and military personnel in the main combat zone. The outbreak had slowed down by October 2009; however, acute viral hepatitis continued to occur sequentially among military personnel. We obtained clinical information and serum samples from 222 patients with acute hepatitis who visited the Military Hospital Anuradhapura between January and September 2010. Samples were subjected to laboratory testing including HAV-immunoglobulin M and genotyping. Most patients (98.2%) were confirmed as having hepatitis A belonging to two subgenotypes: IA and IIIA. We did not observe any differences in clinical or biochemical features among patients with subgenotypes IA and IIIA except for pale stools and upper abdominal discomfort. During the investigation period, we observed a serial outbreak caused by identical HAV strains with an interval in line with that of typical HAV incubation periods. Most patients in the first outbreak were found in the training center, and patients in the second outbreak were found in multiple places where soldiers were assigned after the training center. These findings indicate that a strain of HAV diffused from one place to another along with movement of infected persons among the HAV-susceptible population. HAV vaccination for high-risk groups, such as young soldiers, is necessary.

Hepatitis A Virus Infection, Vaccination and Iranian Healthcare Workers

CONTEXT

Hepatitis A virus (HAV) infection is an important public health problem. It is estimated that about 1.4 million cases of HAV infection occur every year worldwide. Non-immune healthcare workers (HCWs) can be at higher risk of HAV infection in comparison to general population and an appropriate preventive method should be considered for them.

EVIDENCE ACQUISITION

For finding related articles, a comprehensive search was performed in Scopus, PubMed and Google Scholar and all appropriate combinations of following keywords were considered; "healthcare provider", "healthcare personnel", "healthcare worker", "nurse" "medical students", "Iran", "Hepatitis A" and "vaccination". Also we did a search in Persian language in Google scholar and scientific information database (SID) to find related Persian literature.

RESULTS

A gradual shift in age of HAV infection has been seen from childhood toward adulthood. Data about HAV seropositivity among Iranian HCWs are very limited. However based on the recent studies, it seems that HAV seropositivity has been reduced among HCWs in comparison with the past. All recent studies have suggested HAV vaccination for HCWs.

CONCLUSIONS

Available limited studies show that Iranian healthcare personnel need HAV vaccination. However, for selecting an appropriate preventive method for this high risk group, more original studies are still needed.

Isolation and genomic sequence of hepatitis A virus from mixed frozen berries in Italy

Hepatitis A virus (HAV) was detected in two samples of mixed frozen berries linked to Italian hepatitis A outbreak in April and September 2013. Both viruses were fully sequenced by next-generation sequencing and the genomes clustered with HAV complete genomes of sub-genotype IA with nucleotide identities of 95-97%.

Minimum Infective Dose of the Major Human Respiratory and Enteric Viruses Transmitted Through Food and the Environment

Viruses are a significant cause of morbidity and mortality around the world. Determining the minimum dose of virus particles that can initiate infection, termed the minimum infective dose (MID), is important for the development of risk assessment models in the fields of food and water treatment and the implementation of appropriate infection control strategies in healthcare settings. Both respiratory and enteric viruses can be shed at high titers from infected individuals even when the infection is asymptomatic. Presence of pre-existing antibodies has been shown to affect the infectious dose and to be protective against reinfection for many, but not all viruses. Most respiratory viruses appear to be as infective in humans as in tissue culture. Doses of <1 TCID50 of influenza virus, rhinovirus, and adenovirus were reported to infect 50% of the tested population. Similarly, low doses of the enteric viruses, norovirus, rotavirus, echovirus, poliovirus, and hepatitis A virus, caused infection in at least some of the volunteers tested. A number of factors may influence viruses' infectivity in experimentally infected human volunteers. These include host and pathogen factors as well as the experimental methodology. As a result, the reported infective doses of human viruses have to be interpreted with caution.

Heat Inactivation of Hepatitis A Virus in Shellfish Using Steam

Shellfish are an important cause of foodborne viral illness. Consumer-friendly cooking recommendations for shellfish could improve food safety and decrease the risk for infection from contaminated products. Thermal inactivation parameters were established for hepatitis A virus (HAV) in mussels and validated with cooking experiments. Steaming for only 2-5 min was not sufficient to inactivate HAV in mussels in all layers of a steamer. Steaming mussels for 6 min was sufficient to inactivate HAV in all layers. These cooking guidelines produce shellfish with a reduced risk for foodborne virus transmission.

Analysis of 5' nontranslated region of hepatitis A viral RNA genotype I from South Korea: comparison with disease severities

The aim of the study was to analyze genotype I hepatitis A virus (HAV) 5' nontranslated region (NTR) sequences from a recent outbreak in South Korea and compare them with reported sequences from Japan. We collected a total of 54 acute hepatitis A patients' sera from HAV genotype I [27 severe disease (prothrombin time INR ≥ 1.50) and 27 mild hepatitis (prothrombin time INR <1.00)], performed nested RT-PCR of 5' NTR of HAV directly sequenced from PCR products (∼ 300 bp), and compared them with each other. We could detect HAV 5'NTR sequences in 19 of the 54 (35.1%) cases [12 of 27 severe cases (44.4%) and 7 of 27 self-limited cases (25.9%)], all of which were subgenotype IA. Sequence analysis revealed that sequences of severe disease had 93.6%-99.0% homology and of self-limited disease 94.3%-98.6% homology, compared to subgenotype IA HAV GBM wild-type IA sequence. In this study, confirmation of the 5'NTR sequence differences between severe disease and mild disease was not carried out. Comparison with Japanese HAV A10 revealed (222)C to G or T substitution in 8/12 cases of severe disease and (222)C to G or T and (392)G to A substitutions in 5/7 and 4/7 cases of mild disease, respectively, although the nucleotide sequences in this study showed high homology (93.6%-100%). In conclusion, HAV 5'NTR subgenotype IA from Korea had relatively high homology to Japanese sequences previously reported from Japan, and this region would be considered one of the antiviral targets. Further studies will be needed.

[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.

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.

Hepatitis A virus: serology and molecular diagnostics

The diagnosis of hepatitis A virus (HAV) infection is based on the detection of anti-HAV IgM. Shortcomings of this serological approach include the persistence of IgM after normalization of liver enzymes or its detection during polyclonal activation of the immune system due to unrelated viral infection or autoimmune diseases. Molecular diagnosis of HAV along with anti-HAV IgG avidity measurement are helpful in case of positive IgM where laboratory evidence of acute hepatitis is absent and there is no epidemiologic link to other cases. Molecular epidemiology allows us to determine whether viruses from different locations are related to each other and provides further understanding of viral epidemiology by identifying sources and transmission modes. It has been demonstrated that the rapid turnover of HAV strains in low-endemicity countries is caused by their introduction by travelers. Growing sequence databases allow for the identification of geographic origin of viral strains. Collaboration between surveillance laboratories, including database sharing, should be promoted for deeper investigation of outbreaks and improved prevention approaches.

Viral Inactivation in Foods: A Review of Traditional and Novel Food-Processing Technologies

  Over one-half of foodborne illnesses are believed to be viral in origin. The ability of viruses to persist in the environment and foods, coupled with low infectious doses, allows even a small amount of contamination to cause serious problems. An increased incidence of foodborne illnesses and consumer demand for fresh, convenient, and safe foods have prompted research into alternative food-processing technologies. This review focuses on viral inactivation by both traditional processing technologies such as use of antimicrobial agents and the application of heat, and also novel processing technologies including high-pressure processing, ultraviolet- and gamma-irradiation, and pulsed electric fields. These industrially applicable control measures will be discussed in relation to the 2 most common causes of foodborne viral illnesses, hepatitis A virus and human noroviruses. Other enteric viruses, including adenoviruses, rotaviruses, aichi virus, and laboratory and industrial viral surrogates such as feline caliciviruses, murine noroviruses, bacteriophage MS2 and ΦX174, and virus-like particles are also discussed. The basis of each technology, inactivation efficacy, proposed mechanisms of viral inactivation, factors affecting viral inactivation, and applicability to the food industry with a focus on ready-to-eat foods, produce, and shellfish, are all featured in this review.

Rapid detection of anti-hepatitis A virus neutralizing antibodies in a microplate enzyme immunoassay

The slow growth of hepatitis A virus (HAV) in cell culture is one of the primary pitfalls in the development of sensitive and rapid methods for the detection and quantification of HAV and associated neutralizing antibodies. Currently, in vitro assays frequently require 8 days or more to detect and quantify the presence of HAV neutralizing antibodies. This study describes a rapid immunoassay that allowed the detection of anti-HAV neutralizing antibodies in only 3 days. This microplate-based enzymic assay may be applicable in virological diagnostics, in evaluating the immunogenicity of HAV vaccines and in quantifying neutralizing antibodies during the course of HAV infection.

Molecular characterization of hepatitis A virus isolated from acute gastroenteritis patients in the Seoul region of Korea

Hepatitis A virus (HAV) is a major public health problem throughout the world. As a result of declining HAV endemic in Korea, an increasing number of children and adolescents have become susceptible to HAV infection. HAV is related with sanitation conditions of the environment and is transmitted via the fecal-oral route, either through person-to-person contact or by contaminated water and food. The present study has been carried out to determine the phylogenetic analysis and circulating patterns of HAV strains detected from hospitalized patients with acute gastroenteritis (AGE) in the Seoul region of Korea. In total, 2,782 stool specimens from hospitalized patients with AGE collected in October 2006 to September 2007 in Seoul were tested for HAV. A pair comparison of the nucleic acid sequence of a 159-bp base region at the putative VP1/2A junction of 85 Seoul isolates revealed that the most common HAV strain circulating in the region during 2006-2007 was subgenotype IA. HAV phylogenetic studies can provide important information on the genetic characteristics of HAV from AGE patients who may subsequently become the source of infection in Korea.

Efficient neutralizing activity of cocktailed recombinant human antibodies against hepatitis A virus infection in vitro and in vivo

Hepatitis A virus (HAV) is the major pathogen responsible for acute infectious hepatitis A, a disease that is prevalent worldwide. Although HAV immunization effectively prevents infection, primary immunizations must be administered at least 2 weeks prior to HAV exposure. In contrast, passive immunization with pooled human immunoglobulin (Ig) can provide immediate and rapid protection from HAV infection. Because the use of human sera-derived Igs carries the risk of contamination, we sought to develop recombinant HAV-neutralizing human antibodies. We prepared a combinatorial phage display library of recombinant human anti-HAV antibodies from RNA extracted from the blood lymphocytes of a convalescent hepatitis A patient. Two recombinant human IgG antibodies, HAIgG16 and HAIgG78, were screened from the antibody library by their ability to bind with high affinity to purified, inactivated HAV virions. These antibodies recognized different epitopes of the HAV virion capsid, and competed with both patient sera and well-characterized neutralizing mouse monoclonal antibodies. A cocktailed mixture of HAIgG16 and HAIgG78 at a 3:1 ratio was prepared to compare its combined biological activity with that conferred by each antibody individually. The cocktailed antibodies displayed a stronger neutralizing activity in vitro than that observed with either HAIgG16 and HAIgG78 alone. To determine the in vivo neutralizing abilities of these antibodies, rhesus monkeys were inoculated with cocktailed antibodies and challenged with HAV. Whereas control animals developed hepatitis A and seroconverted to the HAV antibody, animals receiving cocktailed antibodies were protected either from viral infection or from developing clinical hepatitis. These results demonstrate that recombinant human antibody preparations could be used to prevent or treat early-stage HAV infection.

Molecular epidemiology of hepatitis A in St. Petersburg, Russia, 1997-2003

The molecular epidemiology of hepatitis A virus (HAV) strains circulating in the St. Petersburg and Karelia regions was studied during 1997-2003. Hepatitis A virus RNA was isolated from both clinical samples (stools or sera) and environmental samples (sewage water). RT-PCR was carried out using different primer pairs from the VP1/2A and VP1 genomic regions, the variable parts of the HAV genome. PCR products were sequenced and 306 nucleotides from the VP1/2A and 332 nucleotides from the VP1 region were used for phylogenetic analysis. The results show that the IA subtype was the most common during the follow-up period: >90% of the isolated HAV strains belonged to that subtype. The HAV strains found in intravenous drug users belonged to subtypes IA and IIIA. Only one out of a total of 88 sequenced strains was of the IB subtype. The subtypes IB and IIIA were found only in 2001-2003, which suggests that new strains were introduced into the endemic situation. The results indicate the usefulness of molecular epidemiological methods in studying changes in the circulating HAV strains and in tracing transmission routes.

Molecular epidemiology of hepatitis A virus in a group of Portuguese citizens living in Lisbon area

Hepatitis A virus (HAV) is the most important cause of acute infectious hepatitis worldwide. In Portugal, due to improvements in sanitation epidemic outbreaks of HAV infection have become less frequent. This report is the first, to our knowledge that characterized HAV in Portugal. For the detection and molecular characterization of HAV cases in a group of Portuguese individuals in the Lisbon area, 31 serum samples were tested: 8 from symptomatic children from an acute hepatitis A outbreak in a Roma (Gipsies) community (2004-2005), and 22 from patients with acute HAV from sporadic cases (2005-2006). A sample of CSF involved in a case of meningitis was also included. IgM anti-HAV detection and nested reverse transcription (RT-PCR), with primers located at the VP1-P2a region, was undertaken to detect HAV genome. In positive samples, molecular characterization was followed by phylogenetic analysis. All samples (n = 31) were positive for IgM anti-HAV. HAV RNA was found in 96.7% of cases. All isolates were classified as genotype I: 22 belonged to sub-genotype IA (73.3%), and 8 to sub-genotype IB (26.7%). All strains obtained from an acute HAV outbreak had sub-genotype IA, in which seven isolates (87.5%) had identical sequences. In HAV sporadic cases sub-genotypes IA and IB were identified, and this may reflect the co-circulation of these two sub-genotypes in Portugal. Molecular epidemiology of HAV infection in this group of Portuguese appears to be similar to other European countries. HAV phylogenetic studies can provide important information for the design of appropriate public health measures.

Shifting seroepidemiology of hepatitis A in Japan, 1973-2003

BACKGROUND

Hepatitis A infection is caused by hepatitis A virus (HAV) contracted through fecal-oral transmission. Life-long immunity is conferred after infection. Improved sanitary conditions have generally resulted in a significant decline in the incidence of hepatitis A. However, a low incidence of infection results in increased HAV susceptibility. The present study investigates the prevalence of anti-HAV antibody and clarifies the current HAV status and HAV susceptibility in Japan at 2003.

METHODS

A total of 2,430 serum specimens collected during 2003 from Japanese individuals ranging in age from 0-92 years, were tested for anti-HAV antibody using an inhibition enzyme linked immunosorbent assay. All specimens were obtained from the WHO and the National Serum Reference Bank/National Institute of Infectious Diseases, Tokyo, Japan.

RESULTS

The overall seroprevalence was 12.2%. Anti-HAV antibodies were rarely detected in individuals between 0-44 years of age. Starting from the age of 45-49 years, seropositivity gradually increased through age 65 years and above. Seroprevalence was not affected by gender, and geographic distribution did not affect age-specific seroprevalence until the age of 60 years.

CONCLUSIONS

HAV susceptibility in Japan is increasing annually. Particularly, the prevalence of anti-HAV antibody in individuals older than 50 years in 2003 was 50.3%, which is significantly lower than that of corresponding studies in 1994 (74.3%), 1984 (96.9%) and 1973 (96.9%). The growing susceptible population of advanced age results in more frequent HAV infection among them. The surveillance of anti-HAV antibody prevalence is useful for implementing preventive measures and for controlling the spread of HAV.

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.

Identification of hepatitis A virus mimotopes by phage display, antigenicity and immunogenicity

A phage-displayed peptide approach was used to identify ligands mimicking antigenic determinants of hepatitis A virus (HAV) for the first time. Bacteriophages displaying HAV mimotopes were isolated from a phage-display peptide library by affinity selection on serum antibodies from hepatitis A patients. Selected phage-peptides were screened for reactivity with sera from HAV infected patients and healthy controls. Four cloned peptides with different sequences were identified as mimotopes of HAV; three of them showed similarity in their amino acid sequences with at least one of the VP3 and VP1 antigenic proteins of HAV. One clone was recognised by 92% of the positive sera. The phagotopes competed effectively with HAV for absorption of anti-HAV-specific antibodies in human sera, as determined by ELISA. The four phage clones induced neutralising anti-HAV antibodies in immunised mice. These results demonstrate the potential of this method to elucidate the disease related epitopes of HAV and to use these mimotopes in diagnostic applications or in the development of a mimotope-based hepatitis A vaccine without the necessity of manipulation of the virus.

Universal mass vaccination against hepatitis A

When first introduced in 1992 the hepatitis A vaccine was recommended for individuals at high risk of exposure. This policy was not expected to have a significant impact on disease incidence at population level in view of the epidemiology of the hepatitis A virus (HAV). More recently two countries, Israel and Bahrain, and regions or subpopulations in others (Australia, China, Byelorussia, Italy, Spain, US) have embarked upon more ambitious vaccination programmes that aim to immunize whole birth cohorts. After a brief survey of the virology and epidemiology of HAV, the disease burden it inflicts and a short history of the development of HAV vaccines--both live (in China) and killed vaccines are available--he vaccination programmes introduced in the countries mentioned above are described. The results have been spectacular: disease incidence, not only in the vaccinated cohorts but also in the whole population, have plummeted within a few years of the start of mass vaccination. There is now convincing evidence that the vaccine confers herd immunity if the main spreaders of the virus are targeted for immunization. This finding should encourage other countries to start mass vaccination programmes against HAV, particularly as pharmacoeconomic studies are beginning to show that such a strategy could be a cost-effective way of controlling the disease. It is now even conceivable to eradicate HAV. In fact, this should be easier to achieve than polio eradication as HAV vaccines confer more durable immunity than polio vaccines. However, the global disease burden of HAV is generally thought not to be high enough to justify such an undertaking in the foreseeable future.

Analysis of the full-length genome of a subgenotype IIIB hepatitis A virus isolate: primers for broadly reactive PCR and genotypic analysis

Among six known subgenotypes (IA, IB, IIA, IIB, IIIA, and IIIB) of human hepatitis A virus (HAV), the complete genomic sequence has not been determined for IIIB. In this study, the full-length genomic sequence of a IIIB HAV isolate (HA-JNG06-90F) recovered from a Japanese patient who contracted sporadic hepatitis A in 1990, was determined. The HA-JNG06-90F genome, which comprised 7462 nt excluding the poly(A) tail, was related most closely to NOR-21 of subgenotype IIIA with an identity of 89.1%, and was only 82.6-83.4% similar to human HAV isolates of genotypes I and II over the entire genome. Comparison of full-length genomic sequences of 20 reported isolates and HA-JNG06-90F generated optimal results for separation of different levels: the nucleotide identities were 80.7-86.6% at the genotype level, 89.1-91.9% at the subgenotype level, and 94.6-99.7% at the isolate level. Similar ranges of nucleotide identity were observed when comparing partial nucleotide sequences of the VP1-2B (481 nt; primer sequences at both ends excluded) and 3C/3D (590 nt) regions, which were amplifiable by PCR with primers designed from well-conserved areas of the HAV genome. All 66 samples with IgM-class HAV antibodies tested positive for HAV RNA by both VP1-2B (481 nt)-PCR and 3C/3D (590 nt)-PCR: subgenotype assignment was concordant in all samples tested (IA [n = 61], IB [n = 1], IIIA [n = 2] and IIIB [n = 2]). These results suggest that two broadly reactive PCRs using primers derived from the VP1-2B and 3C/3D regions, respectively, may be applicable to universal detection and phylogenetic analysis of various HAV strains.

Molecular confirmation of oysters as the vector for hepatitis A in a 2005 multistate outbreak

Numerous hepatitis A outbreaks were linked to the consumption of raw molluscan shellfish in the United States between 1960 and 1989. However, there had been no major molluscan shellfish-associated hepatitis A outbreaks reported in the United States for more than a decade (1989 to 2004). Beginning in late August 2005, at least 10 clusters of hepatitis A illnesses, totaling 39 persons, occurred in four states among restaurant patrons who ate oysters. Epidemiologic data indicated that oysters were the source of the outbreak. Traceback information showed that the implicated oysters were harvested from specific Gulf Coast areas. A voluntary recall of oysters was initiated in September. Hepatitis A virus (HAV) was detected in multiple 25-g portions in one of two recalled samples, indicating that as many as 1 of every 15 oysters from this source was contaminated. Comparing 315 nucleotides within the HAV VPl-2B region, 100% homology was found among four amplicons recovered from a total of six independent experiments of the implicated oysters, and an identical HAV sequence was detected in sera from all 28 patient serum specimens tested. Ten percent heterogeneity over 315 nucleotides (31 variants) was observed between the outbreak strain (subgenotype 1A) and an HM-175 strain (subgenotype 1B) used in the laboratory where the oysters were processed. To our knowledge, this investigation is the first in the United States to identify an HAV-identical strain in persons with hepatitis A as well as in the food that was implicated as the source of their infections.

Recombination and selection in the evolution of picornaviruses and other Mammalian positive-stranded RNA viruses

Picornaviridae are a large virus family causing widespread, often pathogenic infections in humans and other mammals. Picornaviruses are genetically and antigenically highly diverse, with evidence for complex evolutionary histories in which recombination plays a major part. To investigate the nature of recombination and selection processes underlying the evolution of serotypes within different picornavirus genera, large-scale analysis of recombination frequencies and sites, segregation by serotype within each genus, and sequence selection and composition was performed, and results were compared with those for other nonenveloped positive-stranded viruses (astroviruses and human noroviruses) and with flavivirus and alphavirus control groups. Enteroviruses, aphthoviruses, and teschoviruses showed phylogenetic segregation by serotype only in the structural region; lack of segregation elsewhere was attributable to extensive interserotype recombination. Nonsegregating viruses also showed several characteristic sequence divergence and composition differences between genome regions that were absent from segregating virus control groups, such as much greater amino acid sequence divergence in the structural region, markedly elevated ratios of nonsynonymous-to-synonymous substitutions, and differences in codon usage. These properties were shared with other picornavirus genera, such as the parechoviruses and erboviruses. The nonenveloped astroviruses and noroviruses similarly showed high frequencies of recombination, evidence for positive selection, and differential codon use in the capsid region, implying similar underlying evolutionary mechanisms and pressures driving serotype differentiation. This process was distinct from more-recent sequence evolution generating diversity within picornavirus serotypes, in which neutral or purifying selection was prominent. Overall, this study identifies common themes in the diversification process generating picornavirus serotypes that contribute to understanding of their evolution and pathogenicity.

[Microbiological diagnosis of viral hepatitis]

Hepatitis of viral aetiology caused by hepatotropic virus (A, E, B, D and C) represents an important work load for the clinical virology laboratory. Most of the diagnostic is based upon detection in serum and plasma samples of different serological and virological markers, which correlates with different infection stages. In chronic infection by HBV and HCV is necessary to perform diagnostic by molecular methods as well as antigen detection in sequential samples along the course of the disease taking into account that a reliable storage must be provided for stability of structural components of the virus. Recent knowledge about mutations variants in some of the virus may alter the validity of particular markers.

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.

Occurrence of hepatitis A virus genotype III in Germany requires the adaptation of commercially available diagnostic test systems

BACKGROUND

A blood donation, obtained in 2003 in Germany during the preseroconversion diagnostic window period of a hepatitis A virus (HAV) infection, tested HAV-negative by commercially available HAV reverse transcription-polymerase chain reaction (RT-PCR) detection assays.

STUDY DESIGN AND METHODS

The virus responsible for this infection was identified as HAV genotype IIIA by characterization of the nearly complete genome sequence.

RESULTS

Thereby, this HAV variant, which was named strain HMH, was detected in Germany for the first time. Because the commercially available HAV RNA detection systems failed to detect this genotype, a real-time RT-PCR kit was developed that allows quantification and detection of all HAV genotypes. The first nearly full-length nucleotide sequence so far available for HAV genotype IIIA is also provided.

CONCLUSION

This case demonstrates that owing to the genetic variability of HAV, constant monitoring and adaptation of the diagnostic nucleic acid assays are required to guarantee the safety of blood and blood products.

Genetic variability of hepatitis A virus isolates in Rio de Janeiro: implications for the vaccination of school children

The epidemiology of hepatitis A virus (HAV) infection is shifting from high to intermediate endemicity in Brazil, resulting in increased numbers of susceptible individuals and a greater potential for the emergence of outbreaks. Universal vaccination against HAV has been recommended for children, but updated sero-epidemiological data are necessary to analyze the level of natural immunity and to identify candidates for preventive measures. In addition, more molecular studies are necessary to characterize the genotypes involved in HAV infections and outbreaks. Sera from 299 school children (5-15 years old) and 25 school staff members, collected during an outbreak of HAV at a rural public school in June 2000, were tested for IgM and total anti-HAV antibodies (ELISA). Viral RNA was amplified by RT-PCR from anti-HAV IgM-positive sera and from 19 fecal samples. Direct nucleotide sequencing of the VP1/2A region was carried out on 18 PCR-positive samples. Acute HAV infection was detected by anti-HAV IgM in 93/299 children and in 3/25 adult staff members. The prevalence of total anti-HAV antibodies in IgM-negative children under 5 years of age was only 10.5%. HAV-RNA was detected in 46% IgM-positive serum samples and in 16% stool samples. Sequence analysis showed that half the isolates belonged to subgenotype IA and the other half to IB. On the basis of these data, mass vaccination against HAV is recommended without prevaccination screening, especially for children before they enter school, since nearly 90% of the children under 5 years were susceptible. Molecular characterization indicated the endemic circulation of specific HAV strains belonging to subgenotypes IA and IB.

Characterization of the complete genomic sequence of genotype II hepatitis A virus (CF53/Berne isolate)

The complete genomic sequence of hepatitis A virus (HAV) CF53/Berne strain was determined. Pairwise comparison with other complete HAV genomic sequences demonstrated that the CF53/Berne isolate is most closely related to the single genotype VII strain, SLF88. This close relationship was confirmed by phylogenetic analyses of different genomic regions, and was most pronounced within the capsid region. These data indicated that CF53/Berne and SLF88 isolates are related more closely to each other than are subtypes IA and IB. A histogram of the genetic differences between HAV strains revealed four separate peaks. The distance values for CF53/Berne and SLF88 isolates fell within the peak that contained strains of the same subtype, showing that they should be subtypes within a single genotype. The complete genomic data indicated that genotypes II and VII should be considered a single genotype, based upon the complete VP1 sequence, and it is proposed that the CF53/Berne isolate be classified as genotype IIA and strain SLF88 as genotype IIB. The CF53/Berne isolate is cell-adapted, and therefore its sequence was compared to that of two other strains adapted to cell culture, HM-175/7 grown in MK-5 and GBM grown in FRhK-4 cells. Mutations found at nucleotides 3889, 4087 and 4222 that were associated with HAV attenuation and cell adaptation in HM175/7 and GMB strains were not present in the CF53/Berne strain. Deletions found in the 5'UTR and P3A regions of the CF53/Berne isolate that are common to cell-adapted HAV isolates were identified, however.

Hepatitis A Transmitted by Food

Hepatitis A is caused by hepatitis A virus (HAV). Transmission occurs by the fecal-oral route, either by direct contact with an HAV-infected person or by ingestion of HAV-contaminated food or water. Foodborne or waterborne hepatitis A outbreaks are relatively uncommon in the United States. However, food handlers with hepatitis A are frequently identified, and evaluation of the need for immunoprophylaxis and implementation of control measures are a considerable burden on public health resources. In addition, HAV-contaminated food may be the source of hepatitis A for an unknown proportion of persons whose source of infection is not identified.

Foodborne viruses

Foodborne and waterborne viral infections are increasingly recognized as causes of illness in humans. This increase is partly explained by changes in food processing and consumption patterns that lead to the worldwide availability of high-risk food. As a result, vast outbreaks may occur due to contamination of food by a single foodhandler or at a single source. Although there are numerous fecal-orally transmitted viruses, most reports of foodborne transmission describe infections with Norwalk-like caliciviruses (NLV) and hepatitis A virus (HAV), suggesting that these viruses are associated with the greatest risk of foodborne transmission. NLV and HAV can be transmitted from person to person, or indirectly via food, water, or fomites contaminated with virus-containing feces or vomit. People can be infected without showing symptoms. The high frequency of secondary cases of NLV illness and - to a lesser extent - of hepatitis A following a foodborne outbreak results in amplification of the problem. The burden of illness is highest in the elderly, and therefore is likely to increase due to the aging population. For HAV, the burden of illness may increase following hygienic control measures, due to a decreasing population of naturally immune individuals and a concurrent increase in the population at risk. Recent advances in the research of NLV and HAV have led to the development of molecular methods which can be used for molecular tracing of virus strains. These methods can be and have been used for the detection of common source outbreaks. While traditionally certain foods have been implicated in virus outbreaks, it is clear that almost any food item can be involved, provided it has been handled by an infected person. There are no established methods for detection of viruses in foods other than shellfish. Little information is available on disinfection and preventive measures specifically for these viruses. Studies addressing this issue are hampered by the lack of culture systems. As currently available routine monitoring systems exclusively focus on bacterial pathogens, efforts should be made to combine epidemiological and virological information for a combined laboratory-based rapid detection system for foodborne viruses. With better surveillance, including typing information, outbreaks of foodborne infections could be reported faster to prevent further spread.

Hepatitis A: old and new

The hepatitis A virus (HAV), a picornavirus, is a common cause of hepatitis worldwide. Spread of infection is generally person to person or by oral intake after fecal contamination of skin or mucous membranes; less commonly, there is fecal contamination of food or water. Hepatitis A is endemic in developing countries, and most residents are exposed in childhood. In contrast, the adult population in developed countries demonstrates falling rates of exposure with improvements in hygiene and sanitation. The export of food that cannot be sterilized, from countries of high endemicity to areas with low rates of infection, is a potentially important source of infection. After ingestion and uptake from the gastrointestinal tract, the virus replicates in the liver and is excreted into the bile. Cellular immune responses to the virus lead to destruction of infected hepatocytes with consequent development of symptoms and signs of disease. Humoral immune responses are the basis for diagnostic serologic assays. Acute HAV infection is clinically indistinguishable from other causes of acute viral hepatitis. In young children the disease is often asymptomatic, whereas in older children and adults there may be a range of clinical manifestations from mild, anicteric infection to fulminant hepatic failure. Clinical variants include prolonged, relapsing, and cholestatic forms. Management of the acute illness is supportive, and complete recovery without sequelae is the usual outcome. Research efforts during World War II led to the development of passive immunoprophylaxis. Pooled immune serum globulin is efficacious in the prevention and attenuation of disease in exposed individuals. More recently, active immunoprophylaxis by vaccination has been accomplished. Future eradication of this disease can now be contemplated.

Immune globulin and vaccine therapy to prevent hepatitis A infection

The hepatitis A virus is usually transmitted person-to-person due to fecal-oral exchange of virus. Approximately 30,000 infections are reported each year in the United States, with the actual incidence being much greater. Prophylaxis with immune globulin has had a minimal impact on the overall incidence of hepatitis A. The recent availability and proven efficacy of a hepatitis A vaccine offers the hope that the incidence of infection may be substantially reduced. Pre- and postexposure prophylaxis should be targeted to individuals at increased risk of either acquiring infection, transmitting infection, or developing fulminant hepatitis, or to help control epidemics. This article reviews the current literature and discusses recommendations for pre- and postexposure prophylaxis against hepatitis A virus.

Vaccines for hepatitis A and B. The latest recommendations on safe and extended protection

Hepatitis A vaccines (Havrix and Vaqta), administered in two doses, provide long-term protection. Target groups include international travelers, children in high-risk communities, homosexually active men, injecting drug users, persons who work with nonhuman primates, patients with chronic hepatitis, and recipients of clotting factors. The place of hepatitis A vaccination in the childhood-immunization schedule has not been determined. Postexposure prophylaxis for hepatitis A consists of administration of immune globulin within 2 weeks of exposure. Hepatitis B vaccines (Recombivax HB and Engerix-B), administered in three doses, provide protective antibody levels in more than 95% of recipients. Duration of protection appears to approach 10 years. Booster doses are not currently recommended. Hepatitis B vaccination has been incorporated into the routine childhood-immunization schedule. Additional target groups include medical personnel exposed to blood products, household and sexual contacts of infected persons, injecting drug users, and homosexually active men. Postexposure prophylaxis consists of administration of hepatitis B immune globulin as soon after exposure as possible, along with the initial dose of vaccine if desired.