Genetic relatedness of hepatitis A virus strains recovered from different geographical regions

Early infection and asymptomatic spread of hepatitis A virus in a public child care center in Rio de Janeiro, Brazil: should attending children under two years of age be vaccinated?

A cross-sectional study was conducted in order to identify hepatitis A virus (HAV) serological markers in 418 individuals (mean age, 16.4 years; range, 1 month-80 years) at a public child care center in Rio de Janeiro, Brazil, as well as to analyze risk factors and determine circulating genotypes. Serum samples were tested using an enzyme immunoassay. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect and characterize HAV RNA, and sequencing was performed. Anti-HAV antibodies and IgM anti-HAV antibodies were detected, respectively, in 89.5% (374/418) and 10.5% (44/418) of the individuals tested. Acute HAV infection in children was independently correlated with crawling (p < 0.05). In 56.8% (25/44) of the IgM anti-HAV-positive individuals and in 33.3% (5/15) of the IgM anti-HAV-negative individuals presenting clinical symptoms, HAV RNA was detected. Phylogenetic analysis revealed co-circulation of subgenotypes IA and IB in 93.3% (28/30) of the amplified samples. In present study, we verify that 79% (30/38) of children IgM anti-HAV-positive were asymptomatic. In child care centers, this asymptomatic spread is a more serious problem, promoting the infection of young children, who rarely show signs of infection. Therefore, vaccinating children below the age of two might prevent the asymptomatic spread of hepatitis A.

Phylogenetic analysis of global hepatitis E virus sequences: genetic diversity, subtypes and zoonosis

Nucleotide sequences from a total of 421 HEV isolates were retrieved from Genbank and analysed. Phylogenetically, HEV was classified into four major genotypes. Genotype 1 was more conserved and classified into five subtypes. The number of genotype 2 sequences was limited but can be classified into two subtypes. Genotypes 3 and 4 were extremely diverse and can be subdivided into ten and seven subtypes. Geographically, genotype 1 was isolated from tropical and several subtropical countries in Asia and Africa, and genotype 2 was from Mexico, Nigeria, and Chad; whereas genotype 3 was identified almost worldwide including Asia, Europe, Oceania, North and South America. In contrast, genotype 4 was found exclusively in Asia. It is speculated that genotype 3 originated in the western hemisphere and was imported to several Asian countries such as Japan, Korea and Taiwan, while genotype 4 has been indigenous and likely restricted to Asia. Genotypes 3 and 4 were not only identified in swine but also in wild animals such as boar and a deer. Furthermore, in most areas where genotypes 3 and 4 were characterised, sequences from both humans and animals were highly conserved, indicating they originated from the same infectious sources. Based upon nucleotide differences from five phylogenies, it is proposed that five, two, ten and seven subtypes for HEV genotypes 1, 2, 3 and 4 be designated alphabetised subtypes. Accordingly, a total of 24 subtypes (1a, 1b, 1c, 1d, 1e, 2a, 2b, 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 4a, 4b, 4c, 4d, 4e, 4f and 4g) were given.

Case report: Hepatitis A preceding Guillain–Barré Syndrome

A case of acute hepatitis A with Guillain-Barré Syndrome subtype AMAN (acute motor axonal neuropathy) in a 17-year-old male is reported. Serum and cerebrospinal fluid were positive for anti-hepatitis A virus (HAV) IgM, IgG, and IgA. The onset of the syndrome was evident in week 3 of illness. The remarkably high titers of serum anti-HAV IgG appeared unique to a hepatitis A patient with the syndrome. Phylogenetic analysis of the HAV genome detected in the serum and feces revealed genotype IIIA, circulating commonly in Pune, western India.

Co-circulation of genotype IA and new variant IB hepatitis A virus in outbreaks of acute hepatitis in Hungary—2003/2004

Hepatitis A virus (HAV) is one of the most important causes of acute infectious hepatitis worldwide. In Hungary, the reported number of HAV infections has been decreasing in the last four decades, nevertheless, still, each year 500-800 new cases and multiple outbreaks occur, particularly in the northeast region of Hungary. In Hungary, serology is used routinely to establish the diagnosis of HAV infection without genetic analysis of HAV strains for molecular epidemiology. In this study, serum samples collected from symptomatic patients were tested by enzyme-immunoassay (anti-HAV-IgM ELISA) to establish the cause of three acute hepatitis A outbreaks (outbreak 1--from low prevalence region in Southwest Hungary in 2003 and outbreaks 2 and 3 from the endemic region in Northeast Hungary in 2004). Outbreak strains were characterized by reverse transcription-polymerase chain reaction (RT-PCR) amplification of a 360 bp viral VP1/2A region, amplicon sequencing and phylogenetic analysis. Four, seven, and three sera from outbreaks 1, 2, and 3, respectively, were investigated by RT-PCR for HAV genome and HAV RNA was detected in 4 (100%), 4 (57%), and 2 (67%) samples. All strains belonged to genotype I HAV. Outbreak 1 was caused by the new variant subtype IB and outbreaks 2 and 3 caused by genetically identical subtype IA strains. The Hungarian IA and IB hepatitis A viruses had the highest nucleotide identity, 98.4% and 99.0%, to IT-SCH-00 and IT-MAR-02 strains, respectively, detected in year 2000 and 2002 in Italy. Endemic subtype IA and probably imported new variant subtype IB HAV viruses was detected in outbreaks of hepatitis in Hungary that are closely related genetically to HAV strains in Italy.

Detection of hepatitis A virus genotype IB variants in clams from Maputo Bay, Mozambique

Clams provide an important source of food and income for the population of Maputo, Mozambique, where conditions of poor water supply and inadequate sanitation favor endemic infection with hepatitis A virus (HAV). To determine the role of bivalves in an endemic area, clams gathered from Maputo Bay were bought from market and examined for HAV. Four batches, total 150 clams, were sampled over the year. RNA extracted from individual digestive glands was assayed by nested RT-PCR and sequencing of HAV 5' noncoding region (5' NCR). Specific HAV signals were detected in one batch, 23 of 34 clams (67%) testing positive. Phylogenetic analyses of VP3/VP1, VP1/P2A, and 5' NCR determined clustering of clam strains as genotype I, subtype B. In addition to identifying HAV IB strains with predicted conserved amino acid sequence, IB variants exhibiting novel amino acid substitutions at the VP1/P2A junction were detected. HAV strains from clams showed 93%-99% homology with wild-type IB strains from South African outbreaks and from a panel of HAV IgM positive Swedish patients. DNA from enteric human adenovirus 40/41 was found in a limited number of clams from two batches, 6/34 (17%) and 4/35 (11%). Detection of HAV subgenotype IB in bivalves provided indirect evidence of the strains circulating in a densely populated coastal region where HAV is presumed to be hyperendemic. The results suggest that clams may be an important source of HAV in Maputo region, and indicate the need for further molecular study of strains circulating in the indigenous population.

Analysis of sequential hepatitis A virus strains reveals coexistence of distinct viral subpopulations

Hepatitis A virus (HAV) is a hepatotropic member of the family Picornaviridae. Despite a remarkable antigenic stability, recent results have shown that HAV exists in vivo and in cell culture as distributions of genetically related, non-identical variants, referred to as quasispecies. To gain insight into HAV evolution over time in a specific geographical region, genotype I consensus sequences from strains isolated in France in consecutive years were studied. Phylogenetic neighbour-joining method and a non-hierarchical partition analysis, designed to analyse viral quasispecies, indicate that at least five distinct subpopulations of HAV were identified in the course of the disease episode. Strikingly, over time, different subpopulations cycled in dominance. The coexistence of distinct subpopulations whose frequency varies with time is consistent with quasispecies dynamics, and suggests that variation in the dominant HAV population may provide HAV adaptability without being reflected in significant antigenic variation.

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.

An outbreak of hepatitis A virus infection with a high case-fatality rate among injecting drug users

BACKGROUND/AIMS

In 2002, the first reported outbreak of hepatitis A virus (HAV) infection involving mostly intravenous drug users (IDU) occurred in Italy. We attempted a thorough evaluation of the outbreak, including epidemiological, clinical and virological analyses.

METHODS

We conducted an epidemiological investigation, including a case-control study, to identify the source and the modes of HAV transmission. Hepatitis B and C (HCV) viruses and human immunodeficiency virus (HIV) coinfections were clinically analysed. Sequence analysis of the VP1/2A junction of the HAV isolates was also performed.

RESULTS

Of the 47 symptomatic cases, 35 were IDUs. The only associated risk factor was contact (not related to injecting practices) with a jaundiced person (odds ratio: 5.8; 95% confidence interval: 1.3-29.9). Of the cases, 58% were anti-HCV positive and 4.7% anti-HIV positive. Three individuals died of acute liver failure: 2 were HCV-coinfected alcohol abusers, with underlying liver cirrhosis; 1 was HCV/HIV-coinfected. HAV-RNA was found in 15 of the 24 tested patients: genotype IB (8 cases) and IIIA (7 cases) were detected.

CONCLUSIONS

HAV was probably transmitted through the fecal-oral route, although parenteral transmission cannot be excluded. The high fatality rate was probably due to severe underlying liver damage. The occurrence of this outbreak highlights the need for routine HAV vaccination for IDUs.

Detection and differentiation of human hepatitis A strains by commercial quantitative real-time RT-PCR tests

Performance characteristics of two commercial quantitative Hepatitis A virus (HAV) RT-PCR assays, the LightCycler Hepatitis A virus quantification kit (Roche Diagnostics) and the RealArt HAV LC RT PCR kit (artus GmbH) for detection and quantification of HAV were evaluated. Both assays rely on reverse transcription and amplification of extracted RNA. Dilutions of two HAV strains, belonging to different subtypes, were prepared to determine the precision, accuracy, linearity and the detection limit. Both assays were found to be suitable for quantification measurement of HAV RNA, but only the Roche kit was able to distinguish the different HAV strains tested. The linear range for the artus assay was 10(4)-10(6)IU/ml and 2 x 10(4) to 2 x 10(8) RNA copies/ml for the Roche assay. The detection limit of Roche kit was 2 TCID(50)/ml or 500 RNA copies/ml and 5 TCID(50)/ml or 50 IU/ml for the artus kit. Despite these small differences it is concluded that both assays are very suitable for detection and quantification of most prevalent HAV subtypes.

Characterization and genetic variability of Hepatitis A virus genotype IIIA

Molecular epidemiological studies of hepatitis A outbreaks in Norway showed the emergence of Hepatitis A virus (HAV) genotype IIIA in association with parenteral transmission among haemophiliacs and intravenous drug users. The complete genomic sequence of one of these outbreak isolates, NOR-21, was determined. This is the first complete genomic sequence of HAV genotype IIIA. Phylogenetic analysis showed that genotype IIIA/NOR-21 was genetically distinct from the other human and simian genotypes. Phylogenetic analysis of the nucleotide sequences clearly distinguished the different HAV genotypes, regardless of the genomic region used for analysis, whereas the amino acid sequences showed a more vague distinction between human HAV genotypes I and II. In particular, the inferred phylogeny based on the capsid proteins showed that the human HAV strains were related more closely to each other than to the simian strains. The greatest variability and clearest distinction between genotypes were observed for the polymerase gene. The outbreak isolates of HAV genotype IIIA in this study showed greater nucleotide variability than is generally seen in outbreaks of genotype I. This high nucleotide variability, which may be characteristic of this HAV genotype, the mode of transmission in this outbreak or parallel introductions, is discussed.

Sequence variation divides Equine rhinitis B virus into three distinct phylogenetic groups that correlate with serotype and acid stability

Equine rhinitis B virus (ERBV), genus Erbovirus, family Picornaviridae, occurs as two serotypes, ERBV1 and ERBV2, and the few isolates previously tested were acid labile. Of 24 ERBV1 isolates tested in the studies reported here, 19 were acid labile and five were acid stable. The two available ERBV2 isolates, as expected, were acid labile. Nucleotide sequences of the P1 region encoding the capsid proteins VP1, VP2, VP3 and VP4 were determined for five acid-labile and three acid-stable ERBV1 isolates and one acid-labile ERBV2 isolate. The sequences were aligned with the published sequences of the prototype acid-labile ERBV1.1436/71 and the prototype ERBV2.313/75. The three acid-stable ERBV1 were closely related in a phylogenetic group that was distinct from the group of six acid-labile ERBV1, which were also closely related to each other. The two acid-labile ERBV2 formed a third distinct group. One acid-labile ERBV1 had a chimeric acid-labile/acid-stable ERBV1 P1 sequence, presumably because of a recombination event within VP2 and this was supported by SimPlot analysis. ERBV1 rabbit antiserum neutralized acid-stable and acid-labile ERBV1 isolates similarly. Accordingly, three distinct phylogenetic groups of erboviruses exist that are consistent with serotype and acid stability phenotypes.

Development and evaluation of a broadly reactive TaqMan assay for rapid detection of hepatitis A virus

Primers and a TaqMan probe for the 5'-untranslated region (UTR) of the hepatitis A virus (HAV) genome were designed and evaluated. The assay detected 0.5 infectious units of HAV and 40 copies of a synthetic transcript and provides an important screening tool for rapid quantitative HAV detection in clinical or environmental samples.

Influence of load of hepatitis A virus on disease severity and its relationship with clinical manifestations in patients with hepatitis A

BACKGROUND AND AIM

The purpose of the present study was to investigate the influence of viral load on disease severity and analyze the possible relationship of the load of hepatitis A virus (HAV) with disease severity and laboratory findings.

METHODS

Fifty-eight patients diagnosed with acute hepatitis A were used in the current study, of whom 12 patients progressed to severe acute hepatitis (s-AH) defined on the basis of a prothrombin time (PT) of <40% and 46 patients were diagnosed as having mild acute hepatitis (m-AH). The load of HAV was measured with real-time polymerase chain reaction.

RESULTS

Peak viral load showed a significant correlation with alanine aminotransferase (ALT) (r = 0.363, P = 0.0048) and PT levels (r = -0.330, P = 0.0110). In terms of disease severity, there was a significant correlation with ALT (r = 0.462, P = 0.0012) and PT levels (r = 0.400, P = 0.0059) in the m-AH group, but not in the s-AH group. A significant positive correlation of peak viral load with the C-reactive protein level (r = 0.270, P = 0.0400) and a significant negative correlation of peak viral load with the platelet count (r = -0.313, P = 0.0015) was also found.

CONCLUSIONS

The load of HAV was closely correlated with liver damage and disease severity in m-AH, but not in s-AH. The load of HAV was also closely associated with the increase in C-reactive protein level and enhancement of thrombocytopenia.

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.

Phylogenetic analysis of Taura syndrome virus isolates collected between 1993 and 2004 and virulence comparison between two isolates representing different genetic variants

Taura syndrome virus (TSV) is highly pathogenic to Litopenaeus vannamei (Pacific white shrimp) and has caused significant economic loss in the shrimp culture industry. It was first reported from Ecuador in 1992 and has since become widely distributed throughout the Americas and southeast Asia (SE Asia). To determine the genetic relationship among various geographic isolates, we amplified and sequenced a 1.3 kb fragment of the TSV capsid protein gene 2 (CP2) from each of 34 isolates collected from cultured penaeid shrimp stocks in Ecuador, Colombia, Honduras, USA, Mexico, Belize, Thailand, China, and Indonesia. An additional six CP2 sequences obtained from GenBank were included in the analysis. The results indicated low genetic variation (0--5.6% for nucleotide sequence and 0--7.0% for deduced amino acid sequence) among these 40 isolates. A phylogenetic analysis based on the deduced CP2 amino acid sequence revealed three distinct groups: Americas, Belize, and SE Asia. The Belize and SE Asia groups were separated from each other by a 4.7% difference in amino acid sequence. The Belize and Americas groups differed by 4.4%. The Americas and SE Asia groups were the closest, separated by a difference of only 3.3%. Comparison between Belize and Hawaii TSV (reference strain for Americas group) indicated that Belize TSV was more virulent than Hawaii TSV. In bioassays, the Belize isolate caused 50% mortality by 3 days, while the Hawaii isolate caused 50% mortality over 4--6 days. Based on the phylogenetic analysis and virulence comparison, the Belize TSV isolate should be considered as a new variant.

Molecular epidemiology of hepatitis A in Noord-Brabant, The Netherlands

BACKGROUND

Previous studies on the molecular epidemiology of hepatitis A virus (HAV) in Amsterdam, The Netherlands, show that subgenotype 1A is mainly seen among homosexual men practising anonymous oral-anal sex in saunas and darkrooms, while subgenotype 1B is usually detected among children originating from Morocco, and subgenotype 3A is mostly found among travellers to Pakistan.

OBJECTIVE

We studied the genotype distribution in a more rural area of The Netherlands, Noord-Brabant, and compared it with Amsterdam.

STUDY DESIGN

We collected blood and feces samples from 34 HAV IgM(+) individuals who were reported from August 2001-March 2003 at the Municipal Health Service (MHS) Heart for Brabant (Brabant). We also collected feces samples from nine household contacts of whom the HAV IgM status was not known. HAV RNA was isolated and subsequently amplified by reverse transcriptase polymerase chain reaction (RT-PCR) at the VP1-P2a and the VP3-VP1 region, sequenced and analysed.

RESULTS AND CONCLUSIONS

In most cases, relations between risk groups and HAV subgenotypes in Noord-Brabant were similar to those in Amsterdam. Next to genotypes 1 and 3 we also detected a genotype 2/7 strain in a Noord-Brabant case. Also, in contrast to the Amsterdam study, sporadic transmission occurred among various risk groups. Children involved in a school-related outbreak were infected with strains identical to one that was previously isolated from a man who has sex with men (MSM). Also, Dutch patients having no epidemiological link with Turkish or Moroccan children harboured strains imported from high-endemic countries. Furthermore, we report a special case in which HAV may be causally involved in meningitis. The results of this study show that the molecular epidemiology of HAV in The Netherlands can be more complicated than previously anticipated and that HAV phylogenetic studies can provide important information for the design of appropriate public health measures.

Nucleotide correlation between HAV isolates from human patients and environmental samples

Hepatitis A disease is endemic in Albania even though records from the Medical Authority show outbreaks involving only limited numbers of people. In the city of Lac, 200 people became ill following an outbreak of hepatitis A started on November 2002. The age distribution of the cases shows a peak in the age group 5-9 (43.5%) followed by the age group 10-14 (28%) and the age group 1-4 (18%). No cases were recorded in the age group 0-1. Drinking water and sewage samples were collected, using electropositive cartridges, during the outbreak. Rotavirus was identified by RT-PCR in two out of five drinking water samples; however, all the samples tested negative for HAV and astrovirus. Rotavirus was also identified in three out of five sewage samples from which four were HAV positive. HAV-RNA was identified in 28 (62.2%) out of 45 IgM anti-HAV positive sera collected during the outbreak. Genotype IA was expressed from all the amplified samples. Sequence analysis of the overlapping VP1-2A region shows 97-99% homology with three Italian strains IT-SCH-00, IT-ZAM-01, and IT-CAP-00 and one Spanish strain (Sa 30/06/95), whereas the phylogenetic tree built from the 168 bp sequence of the VP1-2A shows four clusters, one including 24 out of 28 RT-PCR positive sera. Considering the deduced amino acid sequence, only one substitution was identified and reported previously for genotype IB.

Phylogenetic analysis of hepatitis A virus in Thailand

Human hepatitis A virus (HAV) is a major causative agent of acute hepatitis, and the isolates are categorised into four genotypes: I (GI), II (GII), III (GIII), and VII (GVII). Although viral hepatitis has been detected under a nationwide surveillance system in Thailand, the genetic variation of HAV has not yet been determined. In the present study, serum specimens were collected from acute hepatitis patients in Thailand from 1998-2002. The IgM-class antibody to HAV was detected in 156 out of 394 sera, counting as many as 39.6% of acute viral hepatitis cases. HAV RNA in the serum specimens was amplified by reverse-transcription polymerase chain reaction (RT-PCR), and a phylogenetic analysis of the putative VP1/2A junction of the genome was performed. The isolates were grouped into two genetic groups, GIA and GIB. This is the first report to identify subgenotype IB (GIB) in Thailand. The genetic segregation was closely related to the province where hepatitis A occurred and the serum specimens were collected. In addition, genetically similar strains were identified in both 1998 and 2001-2002 isolates from two close provinces in the southern part of Thailand, suggesting that a strain indigenous to the province or district has been circulating in southern Thailand.

Rapid investigation of hepatitis A virus outbreak by single strand conformation polymorphism analysis

Investigation of hepatitis A virus (HAV) outbreaks often implies nucleotide sequence analysis. As an alternative method for the identification of related strains, single strand conformation polymorphism method (SSCP) was compared to sequence analysis. Twenty-three strains from sporadic and outbreak cases were studied retrospectively. SSCP, sequence identity and phylogenetic analyses were conducted on a 267 bp fragment of the VP1-2A variable region. The results of SSCP pattern comparison and sequence identity were highly correlated (r = 0.92, P < 0.001). If SSCP showed similar patterns, the VP1-2A fragments had a high and significant probability to have a sequence identity over 99.6%. Results were concordant for outbreak strains. The only discordant result concerned a cluster of three sporadic cases evidenced by phylogenetic analysis while SSCP showed similar patterns for only two of these three cases. A prospective SSCP analysis of a recent HAV outbreak confirmed the reliability of this technique. SSCP may thus provide a rapid and cost-effective tool for preliminary investigation of HAV outbreaks, before undertaking exhaustive nucleotide sequence analysis.

An outbreak of hepatitis A among homeless drug users in Rotterdam, The Netherlands

From the end of January to mid-June 2004 (weeks 5-24) a hepatitis A virus (HAV) outbreak occurred among a homeless and drug user community in Rotterdam, The Netherlands. To prevent further spread of the virus within this group and to the general population, the Municipal Health Service of Rotterdam organized a mass vaccination campaign during which 83% (1,515/1,800) of the homeless people were vaccinated. As part of a national HAV typing study, blood and/or fecal samples of 30 Rotterdam HAV IgM+ patients who fell ill during the period of 1 September 2003-1 December 2004 were tested. The tests included RT-PCR and sequencing at the VP3-VP1 and VP1-P2a regions of the HAV genome. It was found that 12 homeless people, one family member of a homeless person and two people without a known risk were infected with a unique subtype 3a strain. Four of the homeless patients became ill after vaccination and were probably infected at the time. This study shows that Dutch homeless people and drug users involved in HAV outbreaks should be offered HAV vaccine actively to prevent further spread of the infection. Furthermore, it was shown by molecular techniques that the unique subtype 3a strain was not found before the Rotterdam outbreak or afterwards, indicating that the mass vaccination campaign was successful.

High-pressure inactivation of hepatitis A virus within oysters

Previous results demonstrated that hepatitis A virus (HAV) could be inactivated by high hydrostatic pressure (HHP) (D. H. Kingsley, D. Hoover, E. Papafragkou, and G. P. Richards, J. Food Prot. 65:1605-1609, 2002); however, direct evaluation of HAV inactivation within contaminated oysters was not performed. In this study, we report confirmation that HAV within contaminated shellfish is inactivated by HHP. Shellfish were initially contaminated with HAV by using a flowthrough system. PFU reductions of >1, >2, and >3 log(10) were observed for 1-min treatments at 350, 375, and 400 megapascals, respectively, within a temperature range of 8.7 to 10.3 degrees C. Bioconcentration of nearly 6 log(10) PFU of HAV per oyster was achieved under simulated natural conditions. These results suggest that HHP treatment of raw shellfish will be a viable strategy for the reduction of infectious HAV.

Clinical features and molecular characterization of hepatitis A virus outbreak in a child care center in Thailand

BACKGROUND

As a result of declining hepatitis A endemicity in Thailand, an increasing number of children and adolescents have become susceptible to hepatitis A virus (HAV) infection.

OBJECTIVE

The present study was aimed at both investigating the clinical features and determining molecular characterization of HAV during an outbreak, which occurred in a childcare center located in a suburban area of Bangkok between November 2002 and February 2003.

METHODS

Serum samples obtained from all children in the center were tested for anti-HAV IgG and anti-HAV IgM. Testing for HAV-RNA was performed in sera, saliva and stool samples by the reverse transcription-polymerase chain reaction (RT-PCR) with primers located at the VP1-2A region. To further characterize the HAV genotype serum derived HAV-RNA-positive PCR products were sequenced.

RESULTS

Anti-HAV IgG and anti-HAV IgM were detected in 74 and 70 of 112 children in the center, respectively. Among those positive for anti-HAV IgM, 65 cases were asymptomatic, while five children had acute clinical hepatitis. The ratio between symptomatic and asymptomatic children was 1:13. Among the asymptomatic cases, 31 (47.7%) displayed biochemical hepatitis with elevated alanine aminotransferase (ALT) levels. All the isolates from this outbreak were found to be of subgenotype IA, which showed a high level of sequence homology with previous Thai isolates. HAV-RNA could not be detected in saliva, but was found in stool for at least 3 weeks after initial diagnosis of clinical or biochemical hepatitis.

CONCLUSION

Because of the infection's characteristically asymptomatic spread, hepatitis A poses an increased risk to childcare centers. The presence of a single sub-genotype indicates that this HAV strain has been predominantly circulating in Thailand.

Detection of hepatitis A virus RNA in saliva

Hepatitis A virus (HAV) is shed in feces but also in saliva. HAV RNA was detected in saliva in five out of six acutely infected patients with HAV viremia. Serum and saliva sequences were identical. The simplicity of obtaining material allows the recommendation of the use of saliva for investigation of outbreaks.

Genetic analysis of hepatitis A virus isolates from Brazil

A limited number of hepatitis A virus (HAV) isolates from South America have been characterised at the genomic level. IgM anti-HAV positive serum samples collected from patients with hepatitis A living in the five geographical regions of Brazil (North, Northeast, Central, South, and Southeast) were used to obtain HAV isolates and determine their genetic relatedness. Of the 232 case isolates, sequence data were obtained from the VP1/2A junction region of the HAV genome. All isolates were classified in genotype I; 231 belonged to subgenotype IA, and one to subgenotype IB. HAV isolates from four States formed distinct clusters of highly related sequences. However, isolates from other states did not cluster and the sequences from those states were intermingled with sequences found in the other states. The amino acid sequences of all but two isolates showed a Leu --> Ile substitution at position 42 in the 2A protein. This substitution appeared to be a characteristic geographic fingerprint of HAV sequences within Brazil.

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.

Outbreak of infection with hepatitis A virus (HAV) associated with a foodhandler and confirmed by sequence analysis reveals a new HAV genotype IB variant

An outbreak of infection with hepatitis A virus associated with a foodhandler and involving 26 subjects occurred in Southern Italy. Sequence analysis of the VP3-VP1 and VP1-P2A junctions confirmed that the outbreak was due to a point source and allowed the identification of a new genotype IB variant. This report confirms the usefulness of sequence-based molecular fingerprinting during outbreaks.

Detection of hepatitis A virus RNA in serum during the window period of infection

BACKGROUND

Hepatitis A virus (HAV) infection is the leading cause of clinically apparent viral hepatitis in many parts of the world, including developed and developing countries. Only limited information is available regarding the seronegative viremic window that follows HAV infection, and no systematic search has been reported for HAV RNA positive, IgM anti-HAV negative serum samples during hepatitis A outbreaks.

OBJECTIVES

To determine the proportion of HAV infected individuals among (i) children who were tested negative for anti-HAV antibodies during hepatitis A outbreaks which occurred in a public school (n = 157) and a child care center (n = 38); (ii) subjects (n = 46) initially classified as acute non-A-C hepatitis patients after clinical examination and serological tests (sporadic cases).

STUDY DESIGN

Reverse transcription (RT)-PCR was performed to detect the presence of HAV genome in serum samples collected from anti-HAV negative, susceptible subjects.

RESULTS

HAV RNA was detected in 19/157 (12%) and 5/38 (13%) anti-HAV negative children from the public school and child care center, respectively. Twelve (26%) out of the 46 acute hepatitis patients (sporadic cases) were also HAV RNA positive. From nine of these 12 patients, a second blood sample was obtained 18-34 days after the first one: all nine had seroconverted to IgM anti-HAV, and their serum transaminases had reached elevated levels (mean ALT, 418; mean AST, 241).

CONCLUSIONS

Detection of HAV RNA before IgM anti-HAV seroconversion may be used as an early diagnosis method during hepatitis A outbreaks. HAV RNA testing should also help to elucidate acute hepatitis cases of unknown etiology.

Time course of hepatitis A viremia and viral load in the blood of human hepatitis A patients

The hepatitis A virus (HAV) is the most common etiological cause of acute hepatitis infections in humans in industrialized countries. Investigations into the viral load during HAV viremia, however, are rare. Therefore, correlation studies between viral load, biochemical, and specific serological markers have been undertaken. The group of sera comprised a series of multiple consecutive blood samples drawn from 11 patients at different times after onset of the disease. During the period up to 70 days after the onset of icterus, the individual range was at 1 x 10(3) to 3 x 10(4) HAV genome equivalents/ml. From day 75 until 120 after onset of the disease, the levels traced were at 10(3). In one case, it was possible to trace 1.25 x 10(4) genome equivalents/ml up to 180 days after onset of icterus and in two cases even up to 408 and 490 days viral load levels of 5 x 10(3) and 4 x 10(4) were detected, respectively. The same sera were used to measure IgM class antibodies to hepatitis A virus and the total anti-HAV. The results demonstrate that a direct correlation to peak levels of viral load exists with peak serum transaminase levels, but neither with peak anti-HAV IgM levels nor with total anti-HAV. Decreasing amounts of anti-HAV IgM tend to occur with decreasing amounts of HAV genome equivalents; and, vice versa, increasing amounts of total anti-HAV are accompanied by decreasing amounts of HAV genome equivalents. The longest duration of viremia was found in patients infected with HAV genotype IA.

Genetic variability of hepatitis A virus

Knowledge of the molecular biology of hepatitis A virus (HAV) has increased exponentially since its identification. HAV exploits all known mechanisms of genetic variation to ensure survival, including mutation and genetic recombination. HAV has been characterized by the emergence of different genotypes, three human antigenic variants and only one major serotype. This paper reviews the genetic variability and molecular epidemiology of HAV. Its evolutionary mechanisms are described with particular emphasis on genetic recombination and HAV mutation rate. Genotypic classification methods are also discussed.

Evidence for quasispecies distributions in the human hepatitis A virus genome

Nucleotide sequence analysis of multiple molecular clones of the hepatitis A virus (HAV), generated by reverse transcription-PCR of two capsid-coding regions, revealed a degree of heterogeneity compatible with a quasispecies structure in three clinical samples. Passage of plaque-purified reference strain HAV pHM175 43c in FRhK-4 cells documented the generation of a mutant distribution of HAV genomes. The mutant spectra showed mutation frequencies in the range of 1 x 10(-3) to 1 x 10(-4) substitutions per nucleotide, with a dominance of transition over transversion mutations. While in the VP3-coding region, nonsynonymous mutations were predominant; in the VP1-coding region they were uncommon. Around 50% of the amino acid replacements involved residues located at or near antigenic sites. Most of the detected mutations occurred at or in the vicinity of rare codons, suggesting a dynamics of mutation-selection, predominantly at and around rare codons. The results indicate that despite antigenic conservation, HAV replicates as a complex distribution of mutants, a feature of viral quasispecies.

Viral and clinical factors associated with the fulminant course of hepatitis A infection

Fulminant hepatitis is a severe complication of hepatitis A virus infection. Its mechanism is unknown. Liver transplantation can be necessary, but spontaneous recovery is frequent. There are no data on the level of viral replication according to the clinical form of hepatitis A. We reviewed the files of 50 patients with acute hepatitis A. Nineteen patients had fulminant hepatitis (defined by encephalopathy and factor V <50%), and, from them, 10 patients underwent transplantation. Hepatitis A virus (HAV) RNA was quantified by real-time PCR on sera obtained at admission. The genotype was determined by phylogenetic analysis of HAV RNA. HAV RNA was detected in serum by RT-PCR in 39 out of 50 patients. Encephalopathy and low factor V level were significantly related to female gender, HAV PCR negativity (9/19 vs. 5/31, respectively; P =.03), a low serum HAV RNA level (log, 3.6 +/- 0.6 vs. 4.4 +/- 0.9, respectively; P =.02), genotypes other than IA, and acetaminophen intake. In multivariate analysis, low or undetectable HAV viral load and a high bilirubin level were independently associated with both low factor V levels and fulminant hepatitis and also with death or transplantation. In conclusion, HAV-related liver failure is due to an excessive host response associated with a marked reduction in viral load. Serum HAV RNA assay could be of help in the management of severe hepatitis A.

Hepatitis A virus infection in hepatitis C Brazilian patients

OBJECTIVE

HAV infection in patients with pre-existing chronic liver disease has been associated with increased rate of fulminant hepatitis and mortality. The aim of this study was to investigate the presence of serological and molecular HAV markers in a population of HCV infected patients.

PATIENTS AND METHODS

The presence of total and IgM anti-HAV antibodies was investigated in 197 patients (mean age 44.8+/-12.5 years) referred to the Brazilian Reference Center for Viral Hepatitis and who tested positive for anti-HCV antibodies and HCV RNA. HAV RNA was investigated by reverse transcription-nested PCR in these patients.Results. One hundred seventy patients (86%) had total, but not IgM anti-HAV antibodies, being therefore, immune to hepatitis A, while 27 (14%) were not. A high proportion (6/27, 22%) of the susceptible patients presented markers of recent HAV infection: One patient was IgM anti-HAV positive, three were HAV RNA positive, and two presented both markers. By nucleotide sequencing, it was demonstrated that the HAV isolates infecting these patients belonged to subgenotypes 1A and 1B.

CONCLUSIONS

Superinfection with HAV was a common event in the group of HCV infected patients under study. Implementation of hepatitis A vaccination should be considered for this population.

Genetic analysis of HAV strains recovered from patients with acute hepatitis from Southern Italy

Southern Italy is an endemic area for HAV infection contributing to the majority of Italian hepatitis A cases. Using molecular analysis, HAV strains have been classified in distinct genotypes and subgenotypes. To characterize HAV wild-type strains circulating in Southern Italy, sequence analysis of VP3-VP1 and VP1/2A junction regions of HAV isolates recovered from 25 patients with acute hepatitis during 2000 and 2001 was carried out. HAV isolates showed a degree of identity, after pairwise comparison with one another, ranging from 91.9-100% in the VP3-VP1 junction region and 89.9-100% in the VP1/2A junction region. All strains belonged to genotype I, with 84% (21/25) of samples clustering in subgenotype IA and 16% (4/25) in subgenotype IB. Cocirculation of subgenotypes IA and IB was observed among isolates from 2000, whereas all strains from 2001 were subgenotype IA. In addition, the subgenotype IA strains formed different clusters, one of which was related closely to some Cuban strains, showing a percent similarity of 98.8% in the 168-base pair segment encompassing the VP1/2A junction and the same amino acid substitution. The latter finding suggests that this subgenotype variant circulates also in the Mediterranean area. The results of the phylogenetic analysis confirm the genetic heterogeneity among HAV strains in Western Europe.

Evidence of recombination in natural populations of hepatitis A virus

Genetic analysis of selected genome regions of hepatitis A virus (HAV) suggested that distinct genotypes of HAV could be found in different geographical regions. At least seven HAV genotypes have been identified all over the world, including four human genotypes (I, II, III, and VII) and three simian strains (IV, V, and VI). Phylogenetic analysis using full-length VP1 sequences revealed that human strain 9F94 has a close genetic relation with strain SLF-88 (sub-genotype VII). Nevertheless, the same analysis using full-length VP2 or VP3 sequences revealed that strain 9F94 has a close genetic relation with strain MBB (sub-genotype IB). To test the possibility of genetic recombination, phylogenetic studies were carried out, revealing that a crossing over had taken place in the VP1 capsid protein. These findings indicate that capsid-recombination can play a significant role in shaping the genetic diversity of HAV and, as such, can have important implications for its evolution, biology, and control.

Full-length genome of wild-type hepatitis A virus (DL3) isolated in China

AIM: To characterize the genome of an wild-type HAV isolate (DL3) in China.

METHODS: A stool specimen was collected from hepatitis A patient from Dalian, China. HAV (DL3) was isolated and viral RNA was extracted. The genome of DL3 was amplified by reverse transcription and polymerase chain reaction (RT-PCR), followed by cloning into pGEM-T vector. The positive colonies were selected and sequenced. The full-length genome of DL3 was analyzed and compared with other wild-type HAV isolates.

RESULTS: The genome of DL3 was 7476 nucleotides (nt) in size, containing 732-nt 5’untranslated region (UTR), 6681-nt open reading frame (ORF) which encoded a polyprotein of 2227 amino acids (aa), and 63-nt 3’UTR. The base composition was 28.96% A (2165), 16.08% C (1202), 22.11% G(1653) and 32.85% U (2456). Genomic comparisons with wild-type HAV isolates revealed that DL3 had the highest identity of 97.5% for nt (185 differences) with AH1, the lowest identity of 85.7% (1066 differences) with SLF88. The highest identity of 99.2% for amino acid (18 differences) appeared among DL3, AH2 and FH3, and the lowest identity of 96.8% (72 differences) between DL3 and SLF88. Based upon comparisons of the VP1/2A junction and the VP1 amino terminus, DL3 was classified as subgenotype IA. Phylogenetic analysis showed that DL3 was closest to the isolates in Japan.

CONCLUSION: The sequence comparison and phylogenetic analysis revealed that DL3 is most similar to the isolates in Japan, suggesting the epidemiological link of hepatitis A happened in China and Japan.

Persistence of hepatitis A virus in oysters

We investigated the ability of hepatitis A virus (HAV) to persist for up to 6 weeks in Eastern oysters (Crassostrea virginica). Viral RNA was detected by reverse transcription-polymerase chain reaction 6 weeks after 16 h of exposure to 90,000 PFU (180 PFU/ml of seawater) of HAV. Assaying for infectious virus in oysters that received a daily feeding of phytoplankton recovered 3,800, 650, and 500 PFU of HAV 1, 2, and 3 weeks after contamination with 90,000 PFU of HAV, respectively. However, no infectious HAV was isolated from oysters 4, 5, or 6 weeks after contamination. These results support the position that shellfish depuration is insufficient for the complete removal of infectious viruses. Extended relay times (in excess of 4 weeks) may be required to produce virologically safe shellfish.

Mixed infection of a child care provider with hepatitis A virus isolates from subgenotypes IA and IB revealed by heteroduplex mobility assay

Phylogenetic analysis based on a 168 base segment encompassing the putative VP1/2A junction of the hepatitis A virus (HAV) genome has enabled the classification of HAV isolates into seven genotypes (I-VII). Genotype I, which includes the vast majority of the human HAV isolates, has been divided further into subgenotypes IA and IB. An heteroduplex mobility assay was designed with amplification products from the VP1/2A junction region, and used as a genotyping method able to discriminate HAV isolates belonging to IA, IB and non-I genotypes. The method was used to successfully genotype 48 samples (16 IA and 32 IB). However, one HAV RNA positive serum sample (AUX-23), collected from a 15 year old female employed at a child care center located in Rio de Janeiro, Brazil, showed an unusual pattern. PCR products from sample AUX-23 gave rise to heteroduplex bands when mixed with IA products as well as with IB products, suggesting the presence of HAV isolates from both subgenotypes in the serum. PCR products from sample AUX-23 were then cloned and 20 clones were analyzed by heteroduplex mobility assay. Eleven were subgenotype IA and 9 were IB. Three clones of each subgenotype were then sequenced to confirm the results. These data constitute the first report of mixed infection of a single individual with different HAV isolates.

Genome variability and capsid structural constraints of hepatitis a virus

The number of synonymous mutations per synonymous site (K(s)), the number of nonsynonymous mutations per nonsynonymous site (K(a)), and the codon usage statistic (N(c)) were calculated for several hepatitis A virus (HAV) isolates. While K(s) was similar to those of poliovirus (PV) and foot-and-mouth disease virus (FMDV), K(a) was 1 order of magnitude lower. The N(c) parameter provides information on codon usage bias and decreases when bias increases. The N(c) value in HAV was about 38, while in PV and FMDV, it was about 53. The emergence of 22 rare codons in front of 8 in PV and 7 in FMDV was detected. Most of the conserved rare codons of the P1 region were strategically located at the carboxy borders of beta barrels and alpha helices, their potential function being the assurance of proper folding of the capsid proteins through a decrease in the translation speed. This strategic location was not observed for amino acids encoded by the conserved rare codons of the 3D region. The percentage of bases with low pairing number values was higher in the latter region, suggesting a role of the conserved rare codons in the maintenance of RNA structure. Many of the rare codons in HAV are among the most frequent in humans, unlike in PV or in FMDV. This fact may be explained by the lack of cellular shutoff in HAV. One hypothesis is that HAV has evolved in order to avoid competition with its host for cellular tRNAs.

Role of viruses in human evolution

The study of viral molecular genetics has produced a considerable body of research into the sequences and phylogenetic relationships of human and animal viruses. A review of this literature suggests that humans have been afflicted by viruses throughout their evolutionary history, although the number and types have changed. Some viruses show evidence of long-standing intimate relationship and cospeciation with hominids, while others are more recently acquired from other species, including African monkeys and apes while our line was evolving in that continent, and domesticated animals and rodents since the Neolithic. Viral selection for specific resistance polymorphisms is unlikely, but in conjunction with other parasites, viruses have probably contributed to selection pressure maintaining major histocompatibility complex (MHC) diversity and a strong immune response. They may also have played a role in the loss in our lineage of N-glycolylneuraminic acid (Neu5Gc), a cell-surface receptor for many infectious agents. Shared viruses could have affected hominid species diversity both by promoting divergence and by weeding out less resistant host populations, while viruses carried by humans and other animals migrating out of Africa may have contributed to declines in other populations. Endogenous retroviral insertions since the divergence between humans and chimpanzees were capable of directly affecting hominid evolution through changes in gene expression and development.

Molecular characterization of hepatitis a virus isolates from a transcontinental shellfish-borne outbreak

One hundred eighty-four serologically confirmed cases of hepatitis A were reported in eastern Spain in 1999. A matched case-control study implicated imported coquina clams complying with European Union shellfish standards as the source of infection; this implication was confirmed by the detection by reverse transcription-PCR of hepatitis A virus (HAV) RNA in shellfish samples. In spite of the recognized low variability of HAV, genetic characterization of the complete capsid region of virus isolates from patient serum samples revealed the existence of both synonymous and nonsynonymous variants. Two antigenic variants were detected, one in a discontinuous epitope defined by monoclonal antibody K3-4C8 and a second in a linear VP1 epitope of the virus. In spite of these antigenic variants, all isolates were assigned to genotype IB, providing further evidence that the outbreak originated from a common source, although multiple strains were likely to be involved.

Molecular characterization of hepatitis-A-virus infections, in the context of two outbreaks in southern Thailand

As hepatitis A virus (HAV) is usually transmitted through the faecal-oral route, hepatitis A is a communicable disease. In countries of intermediate to low endemicity, sudden outbreaks of human infection with the virus may occur. Between September 2001 and April 2002, there were two outbreaks of HAV infection in the Ruso and Yeengor districts of Narathiwas province, in southern Thailand. Isolates of HAV were recovered during these outbreaks, from 14 in-patients with acute hepatitis in Ruso (12 positive for anti-HAV IgM and all positive for HAV RNA), 16 children with asymptomatic infection in Yeengor (14 positive for anti-HAV IgM and nine for HAV RNA), and four isolated cases in Bangkok (all positive for anti-HAV IgM). Molecular characterization of the VP1-P2A region of each isolate was followed by phylogenetic analysis. All of the isolates from Narathiwas province were found to be of genotype 1a, to have the same VP1 nucleotide sequence, and to show a high level of sequence homology (>/= 99.5%) with the isolates from Bangkok and with previous Thai isolates. These results should facilitate further research into HAV transmission and genotype identification in community outbreaks.

Genetic characterization of hepatitis A virus isolates from Buenos Aires, Argentina

The Hepatitis A virus (HAV) has been classified in seven different genotypes, which include human (I, II, III, and VII) and simian (IV, V, and VI) groups. The sequence analysis of HAV strains contributes to the molecular epidemiology of the virus. Although the infection with HAV is endemic in Argentina and vaccination is being implemented in this country, using both IA and IB strains, there are very few data on the genotypes of the circulating viruses. On the basis of the sequences of 20 isolates collected in Buenos Aires during a 2-year period (extended to 3 years by two additional specimens), we observed the presence of a single sub-genotype, IA, but with a high genetic diversity. We analyzed the VP1-2A junction and also the VP3-VP1 region. Most of the Argentine isolates grouped in at least two clusters. One of these was related to South American strains, thus suggesting a co-circulation of related isolates in neighbor countries. The other cluster was composed only of Argentine specimens. Other sequences were more scattered along the phylogenetic tree. However, we demonstrated that a consistent genetic relatedness of sequences could only be inferred on the basis of a more extensive sequencing of each isolate.

Molecular evolution of hepatitis A virus: a new classification based on the complete VP1 protein

Hepatitis A virus (HAV) is a positive-stranded RNA virus in the genus Hepatovirus in the family Picornaviridae So far, analysis of the genetic variability of HAV has been based on two discrete regions, the VP1/2A junction and the VP1 N terminus. In this report, we determined the nucleotide and deduced amino acid sequences of the complete VP1 gene of 81 strains from France, Kosovo, Mexico, Argentina, Chile, and Uruguay and compared them with the sequences of seven strains of HAV isolated elsewhere. Overall strain variation in the complete VP1 gene was found to be as high as 23.7% at the nucleotide level and 10.5% at the amino acid level. Different phylogenetic methods revealed that HAV sequences form five distinct and well-supported genetic lineages. Within these lineages, HAV sequences clustered by geographical origin only for European strains. The analysis of the complete VP1 gene allowed insight into the mode of evolution of HAV and revealed the emergence of a novel variant with a 15-amino-acid deletion located on the VP1 region where neutralization escape mutations were found. This could be the first antigenic variant of HAV so far identified.

Prolonged hepatitis A infection in an HIV-1 seropositive patient

Hepatitis A virus (HAV) is a worldwide disease; in most cases, it causes an acute self-limited illness that does not lead to a chronic state. The course of HAV viremia in a homosexual male with human immunodeficiency virus type 1 (HIV-1) and the correlation between HIV and HAV viral load, alanine aminotranferase (ALT) level, and CD4(+) lymphocyte count were investigated during the course of the infection. HAV RNA was detected quantitatively up to 256 days after clinical onset. To our knowledge, this specific case is the first report of a prolonged infection with hepatitis A in a male with HIV-1. The ALT levels decreased gradually; however, 286 days after clinical onset of hepatitis, ALT levels were three times higher than normal values. HIV viral load was not affected by the infection with HAV and CD4(+) cell count was stable during the course of the co-infection. The duration and the high-titer viremia of hepatitis A virus in an immunodeficient patient constitute a serious risk of the spread of hepatitis A within this population. As inactivated HAV vaccine is safe in HIV-positive subjects, it would be wise to establish a strategy of preventive vaccination in this high-risk group.

Detection of both hepatitis A virus and Norwalk-like virus in imported clams associated with food-borne illness

Hepatitis A virus (HAV) and Norwalk-like virus (NLV) were detected by reverse transcription-PCR in clams imported into the United States from China. An epidemiological investigation showed that these clams were associated with five cases of Norwalk-like gastroenteritis in New York State in August 2000 (Food and Drug Administration Import Alert 16-50). They were labeled "cooked" but appeared raw. Viral RNA extraction was performed by using dissected digestive tissues rather than whole shellfish meats; this was followed by glycine buffer elution, polyethylene glycol precipitation, Tri-Reagent treatment, and purification of poly(A) RNA with magnetic beads coupled to poly(dT) oligonucleotides. We identified HAV and NLV as genotype I and genogroup II strains, respectively. Both viruses have high levels of homology to Asian strains. An analysis of fecal coliforms revealed a most-probable number of 93,000/100 g of clam meat, which is approximately 300-fold higher than the hygienic standard for shellfish meats.

Microbial quality of wastewater: detection of hepatitis A virus by reverse transcriptase-polymerase chain reaction

AIMS

The persistent circulation of hepatitis A virus (HAV) in the Mediterranean area suggests the need for monitoring its presence in the environment. A reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the presence of HAV in several consecutive raw sewage and final effluent samples, collected over an 8-month period from an activated sludge treatment plant in southern Italy.

METHODS AND RESULTS

Two distinct purification protocols, either based on antigen-capture with monoclonal antibody (AC) or RNA extraction, were compared. The possible influence of the antibody used in the AC phase was evaluated in preliminary experiments on HAV-spiked samples, using two different monoclonal antibodies. Hepatitis A virus RNA was detected in all but one sewage environmental sample examined. The contemporary presence of enteroviruses, reoviruses and phages was observed, while HAV growth in cell culture was hampered.

CONCLUSIONS

The RT-PCR technique was confirmed to be a valuable tool for the rapid monitoring of HAV in sewage samples. In addition, this study demonstrated that application of different sample purification methods can result in different levels of sensitivity of the assay and that, in the antigen-capture method, the choice of antibody can have a crucial role.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work underlines the need for technical uniformity in environmental studies from different laboratories for a correct and useful comparison of the results.