[Hepatitis viruses infection situation in Mianyang of the Sichuan province]

OBJECTIVE

To investigate the seroprevalence of hepatitis viruses in Mianyang of the Sichuan province.

METHODS

EIISA was used for detecting anti-HAV IgG, HBsAg/HBsAb, anti-HCV IgG and anti-HEV IgG of the serum samples. All sample were collected in Mianyang areas in 2007.

RESULTS

1352 samples were detected. The positive rates of anti-HAV, HBsAg/HBsAb, anti-HCV,and anti-HEV are 81.07% (1096/1352), 5.40% (73/1352) and 61.32% (829/1352), 0.37% (5/1352) and 49.26% (666/1352), respectively. The positive rate at different age group, for anti-HAV was 38.21% of 10-19 years old, 83% of 20-29 years old, 88% of 30-39 years old, 95.03% of 40-49 years old, 97% of 50-59 years old, 97.77% of 60-69 years old, 97.52% of > or =70 years old. For HBsAg/HBsAb were 5.65% or 50.83%, 10.0% or 68.0%, 5.20% or 78.80%, 5.97% or 78.11%, 6.50% or 62.50%, 1.12% or 51.40%, 4.96% or 30.58% at the same age group, respectively,for anti-HCV, was 0.33% of 10-19 years old, 0.80% of 30-39 years, 0.56% of 60-69 years old, 0.83% of > or =70 years old.For HEV-IgG was 26.58% of 10-19 years old, 42.0% of 20-29 years old, 55.22%-61.0% of 30-> or =70 years old, for anti-HEV IgM, was 10.06% (53/527) in the positive samples of HEV-IgG.

CONCLUSION

The inoculation againt HAV and HBV is enhanced in the young population. HBsAg carrier and HCV infection is decreasing. The HEV infection is actually increasing.

Genetic analysis of hepatitis A virus outbreak in France confirms the co-circulation of subgenotypes Ia, Ib and reveals a new genetic lineage

Genetic analysis of selected genome regions of hepatitis A Virus (HAV) suggested that distinct genotype could be defined in different geographic locations. In order to study the degree of genetic variability among HAV isolated during a single epidemic outbreak, sequences from a 148 base pair segment within the VP1 amino terminal region were obtained for eight distinct HAV isolates from an outbreak that occurred in North Bretagne (France). These sequences were compared among themselves and with published sequences from 30 different strains that represented different HAV sub-genotypes that were isolated all over the world. Phylogenetic analysis revealed an extensive genetic heterogeneity among strains belonging to the same outbreak and revealed co-circulation of sub-genotype IA, IB, and the presence of IIIA sub-genotype for the first time in a Mediterranean country.

[Characteristics of the manifest and latent components of the hepatitis A epidemic process in cities of Russia]

Seroepidemiological study of hepatitis A (HA) morbidity was carried out in three Russian cities, with different levels of HA morbidity. The study included the analysis of HA morbidity for 22 years, the determination of antibodies to HA virus (anti-HAV) in 2,958 healthy persons aged 0-12 months to 40 years and older. In one of the cities 7 isolates of HA virus were obtained from unrelated sources and the genotypes of the virus were determined. The study revealed that the frequency of seropositive cases among persons of different ages correlated with the level and prolonged dynamics of HA morbidity. According to the occurrence of anti-HAV, such cities as St. Petersburg, Rostov-on-Don and Yakutsk may be at present classified as territories, moderately endemic in HA. At the same time in the 90 s the epidemic situation in HA was more favorable in Rostov-on-Don than in two other cities. The suggestion was made that a high proportion of seropositive persons among the population of St. Perersburg was linked with an almost twofold rise in HA morbidity in 1993-1995 caused by genotype 1 of the virus. Seroepidemiological studies in HA during the period of a drop in morbidity acquire special importance in the surveillance and control system of this infection.

Molecular epidemiology of hepatitis A virus in Korea

BACKGROUND

The prevalence of antibodies for hepatitis A virus (anti-HAV) in adolescents and young adults has decreased remarkably following the economic growth in Korea. As a result, this age group has a high risk for HAV infection paradoxically, and over 1500 cases of clinically overt hepatitis A occurred in 1998. Human isolates of hepatitis A virus (HAV) are categorized within four genotypes (I, II, III, and VII). In some geographic regions, closely related isolates cluster, suggesting endemic spread of the virus, while in other regions multiple genotypes circulate. Virtually no data are available with regard to the genetic relatedness of Korean strains of HAV.

METHODS AND RESULTS

A 168 base pair segment encompassing the putative VP1/2A junction of the HAV genome was amplified by RT-PCR and sequenced in sera of 18 Korean patients with a sporadic form of acute hepatitis A. Pairwise comparisons of the nucleic acid and amino acid sequences of 18 Korean isolates with one another revealed that the Korean isolates showed > 94.6% and > 96.4% identity, respectively. All of the 18 Korean isolates clustered within genotype IA, irrespective of the geographic locations and the time that hepatitis occurred. Unique amino acid sequence changes that had never been reported in genotype IA were found in nine of the 18 isolates. These changes were Gln-->Ser and Lys-->Arg in 2A-19 and 2A-10 amino acid positions.

CONCLUSION

The presence of single genotype and unique mutations may be related with the circulation of endemic HAV over a long period of time in Korea.

An outbreak of hepatitis A associated with green onions

Forty-three cases of serologically confirmed hepatitis A occurred among individuals who ate at restaurant A in Ohio in 1998. Serum samples from all restaurant A employees who worked during the exposure period were negative for IgM antibodies to hepatitis A virus (HAV). A matched case-control study determined that foods containing green onions, which were eaten by 38 (95%) of 40 case patients compared with 30 (50%) of 60 control subjects, were associated with illness (matched odds ratio, 12.7; 95% confidence interval, 2.6-60.8). Genetic sequences of viral isolates from 14 case patients were identical to each other and to those of viral isolates from 3 patients with cases of hepatitis A acquired in Mexico. Although the implicated green onions, which could have come from one of 2 Mexican farms or from a Californian farm, were widely distributed, no additional green onion-associated cases were detected. More sensitive methods are needed to detect foodborne hepatitis A. A better understanding of how HAV might contaminate raw produce would aid in developing prevention strategies.

Molecular epidemiology of hepatitis A virus in Amsterdam, the Netherlands

The transmission of sporadic community-acquired hepatitis A virus (HAV) among different risk groups in Amsterdam was verified by applying molecular techniques on fecal samples. These were collected in 1997/1998 from 33 persons with HAV infection that was confirmed serologically. From 8 of these persons serial stool samples were collected. Nested RT-PCR targeting the VP3-VP1 and VP1-P2a regions followed by sequence analysis established the duration of fecal HAV RNA excretion in stool and the epidemiological molecular relationships between patients. The samples of 31 patients were RT-PCR positive, of which 24 were positive for both regions. Fecal HAV shedding was found to occur for at least 33 days after onset of disease, which was the longest time span tested. Sequencing showed that the hepatitis A virus subgenotype circulating among persons from Moroccan descent (type IB) was different from the subgenotype circulating among Dutch homosexual men (type IA). If the latter is endemic in the Netherlands, its presence is of importance to the national vaccination strategy.

[Magnitude of rainfall on viral contamination of the marine environment during gastroenteritis epidemics in human coastal population]

BACKGROUND

Sewage treatments are not efficient to eliminate enteric microorganisms. Viruses are able to persist and are discharged into the marine environment with treated effluents. Few data are now available on the magnitude and the contributive processes of marine viral contamination. This work evaluates the relationship between the magnitude of rainfall and the viral contamination of the marine environment during winter epidemics of gastroenteritis in human coastal populations.

METHODS

A RT-PCR method was used to detect enterovirus, hepatitis A virus, Norwalk-like virus, astrovirus and rotavirus in shellfish, harvested monthly between August 1995 and July 1998. The frequency of virus detection in shellfish was expressed as an Index of Viral Contamination. Acute gastroenteritis in the population was estimated using the French Sentinel System for Monitoring of Communicable Diseases. Rainfall effects on the efficiency of sewage treatment were assessed using an estimated staying time of sewage effluents in the plant.

RESULTS

The results indicate that the highest viral contamination occurs in winter. Maximal indexes of viral contamination were respectively 70% in January 1996, 100% in January 1997, but only 31% in January 1998. Viral contamination variations seemed to follow the pattern of the winter epidemic of acute gastroenteritis in the local population in 1996 and 1997. These observations should be linked to the winter rainfalls. Heavy rains on short periods of time could create an hydraulic overload in the sewage treatment plant, reducing the staying time of the sewage effluents and thus the efficiency of the disinfection process.

CONCLUSION

The magnitude of the viral contamination of shellfish seems to result from the simultaneity between the winter epidemics of acute gastroenteritis in the coastal population and heavy rainfall. To prevent public health hazards associated with shellfish consumption, the monitoring of microbiological quality in shellfish harvesting areas should include accompagning survey of viral epidemic in the coastal population, and of sewage outputs in the coastal environment.

Hepatitis A virus sequence detected in clotting factor concentrates associated with disease transmission

Since the early 1990s hepatitis A virus (HAV) infections among recipients of solvent-detergent treated factor VIII concentrates have occurred in Europe, South Africa and the United States. A review of the epidemiological and laboratory-based investigations of the outbreaks in Germany and Ireland were consistent with transmission by factor concentrates but limited information about transmission based upon nucleic acid sequences was obtained, and no clear chain of transmission could be established. Within the United States, hepatitis A infections associated with solvent detergent concentrate occurred in a single patient in 1993, and a cluster of cases in 1995. Although the 1993 factor concentrate was positive for virus, samples from the patient were not available. The virus present in the cluster of 1995 factor VIII patients, the factor concentrate they received, and the original plasma pool was identical, while the virus identified in the factor IX patient differed by a single base.

Characterisation of an epidemic of hepatitis A virus involving intravenous drug abusers--infection by needle sharing?

An epidemic of hepatitis A virus (HAV) among intravenous drug abusers in Oslo involved 144 serologically confirmed cases. Another 26 patients (non-drug abusers), of whom 14 were derived from a single nosocomial outbreak, were associated with the epidemic. Sequencing of the VP1/P2A junction revealed that viruses associated with the epidemic were completely identical, whereas other HAV samples collected during the same period differed by up to 10%. HAV was detected in the serum of 48 of 100 patients by a nested PCR. Viremia was observed as early as 25 days before the onset of clinical hepatitis, and up to 30 days after. The large number of patients within the drug abuser group, and the few secondary cases, raised the question of whether the virus could be transmitted by the use of needles. To establish whether viral contamination of drugs did contribute appreciably to maintaining the epidemic, we examined heroin and amphetamine confiscated during the period, using immunomagnetic separation coupled to nested PCR, but failed to detect any virus. Antibodies against hepatitis B virus and hepatitis C virus were common among the HAV infected drug abusers (43% and 81%, respectively), suggesting widespread sharing of needles. This observation and the large number of patients with a demonstrable viremia suggest that needle sharing may contribute to the dissemination of HAV.

Molecular epidemiology of South African strains of hepatitis A virus: 1982-1996

Isolates of hepatitis A virus (HAV) are of a single serotype, with human isolates being categorised within four genotypes. In addition, there are three genotypes exclusively associated with Old World monkeys. In some geographical regions, related isolates cluster suggesting endemic spread of the virus, while in other regions several genotypes circulate. Virtually no data are available with regard to the genetic relatedness of South African (SA) strains of HAV. A 177 base segment within the VP1 region and a 168 base segment encompassing the putative VP1/P2A junction of 20 clinical and one environmental wild-type isolate(s) of HAV from SA were amplified by reverse transcriptase-polymerase chain reaction. The nucleotide sequences from the SA isolates showed > 85% nucleic acid sequence identity with published sequences for HAV strains from genotype I, with the majority of strains (81%) clustering within subgenotype IB and the remainder in subgenotype IA. A high degree of conservation was noted between the predicted amino acid sequences from SA clinical isolates and isolates from the rest of the world. Data presented indicate that in SA there is a circulating population of endemic HAVs from two distinct subgenotypes. This study provides valuable new data on the genetic relatedness of HAVs from southern Africa and the distribution of subgenotype IB.

Hepatitis A outbreak amongst intravenous amphetamine abusers in Finland

This article describes a widespread outbreak of hepatitis A virus (HAV) infection amongst drug abusers in Finland. Although attempts to demonstrate the virus in amphetamines failed, the infection was assumed to be linked to intravenous use of the drug. The unusual mode of transmission prompted us to analyse possible atypical clinical features as well as the spread of the virus to the general population, nowadays practically without protective immunity. Serologically verified cases that occurred in Helsinki were interviewed, their hospital records were analysed and their contacts were serology tested. Amphetamine lots, as well as faecal samples from patients, were examined with RT-PCR. Detailed information was obtained from 238 subjects, among whom 131 admitted drug abuse and 67 cases were classified as secondary cases. Phylogenetic analysis of virus strains from HAV-infected cases suggested a common origin, and epidemiological observations linked it with particular lots of amphetamine. Three cases died, and 3 presented with severe clinical disease. Icterus was more common among i.v. drug abusers than others. Infection with hepatitis A virus was probably related to the faecal contamination of amphetamine associated with the transportation of the drugs in the gastrointestinal tract.

Molecular epidemiology of an outbreak of hepatitis A in Italy

The relationship of hepatitis A virus (HAV) isolates associated with an outbreak in Genoa, Italy, in 1993 was examined using direct sequencing of amplicons derived by antigen capture PCR (AC/PCR) from faecal samples of the infected persons. Forty samples recovered from 38 primary and two secondary cases were examined. The latter were household contacts of the primary cases. In addition, faecal material of 2 unrelated persons infected simultaneously with hepatitis A in Genoa were tested. The PCR products derived from the P1/P2 junction of the HAV genome were analysed. A 100% nucleotide identity was detected between the viral isolates originating from the primary as well as the secondary cases. The viral isolates recovered from the faecal samples of the two unrelated cases differed from the virus causing the outbreak as well as from each other. These results indicate that a single HAV strain caused the outbreak. The virus might have been transmitted by ingestion of contaminated food or water since all hepatitis A infected employees of the factory had eaten in the same canteen. Definitions of HAV genotypes are based on numerous genetic comparisons of different strains. The sequence comparison of the investigated isolates with published HAV sequences of the P1/P2 genome region revealed that the virus associated with the outbreak belongs to HAV subgenotype IA, whereas the strains recovered from the viral isolates of the unrelated cases belong to subgenotype IB.

Direct sequencing of hepatitis A virus strains isolated during an epidemic in France

Direct sequencing of PCR products was used to study the VP1 region of the hepatitis A virus (HAV) genome (position 2199 to 2356) of nine strains isolated from human stools collected during a hepatitis A epidemic (western France, 1992), three strains from environmental samples (1990, 1991, and 1992), and two HAV cell culture isolates (the French strain CF53/Lyon and strain CLF). These viruses differed from CF53/Lyon (genotype I) by between 1 and 10.3%, and results indicated the existence of two groups of strains belonging to two different subgenotypes (IA and IB). With this sequencing technique it was possible to monitor the epidemiology of HAV and study its relations.

[Hereditable characteristics of attenuated live hepatitis A virus H2 strain]

The toxicity of attenuated hepatitis A virus H2 strain was not increased in testing KMB 17 cells of 5 consecutive generations of monkeys at 36 degrees C. After injection of attenuated live hepatitis A virus H2 strain in humans, no abnormality was noted. Serum hepatitis A antigen was positive after 38 children aged 3-9 years were given oral 10(6.5) TCKD50, whereas it was 100% positive in the group of same age after percutaneous vaccination. Noninfection of oral administration is an important hereditable characteristic differentiation from wild strains.

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

A pairwise comparison of the nucleic acid sequence of 168 bases from 152 wild-type or unique cell culture-adapted strains of hepatitis A virus (HAV) revealed that HAV strains can be differentiated genetically into seven unique genotypes (I to VII). In general, the nucleotide sequence of viruses in different genotypes differs at 15 to 25% of positions within this segment of the genome. Viruses from four of the genotypes (I, II, III and VII) were recovered from cases of hepatitis A in humans, whereas viruses from the other three genotypes (IV, V and VI) were isolated only from simian species developing a hepatitis A-like illness during captivity. Among non-epidemiologically related human HAV strains, 81 were characterized as genotype I, and 19 as genotype III. Within each of these major genotypes, there were two distinct groups (subgenotypes), which differed in sequence at approximately 7.5% of base positions. Each genotype and subgenotype has a characteristic amino acid sequence in this region of the polyprotein, with the most divergent genotypes differing at 10 of 56 residues. Strains recovered from some geographical regions belonged to a common (endemic) genotype, whereas strains from other regions belonged to several, probably imported, genotypes. Thus, HAV strains recovered in North America were for the most part closely related at the nucleotide sequence level, whereas in other regions, such as Japan and Western Europe, HAV strains were derived from multiple genotypes or sub-genotypes. These data indicate that patterns of endemic transmission can be differentiated from situations in which infections are imported due to travel.

Natural hosts of hepatitis A virus

The host range for hepatitis A virus (HAV) is limited to man and several species of non-human primates, and involvement of vertebrates other than primates in HAV circulation is unlikely. Spontaneous hepatitis A infection has been reported to occur in captive non-human primates including the great apes (chimpanzee) as well as Old World (cynomolgus, African vervet, stump-tailed) and New World (aotus) monkeys. The presence of anti-HAV antibody in the sera of newly captured monkeys of these species shows that infection may also spread in their natural habitat. HAVs isolated from spontaneously infected monkeys, although antigenically closely related to human HAV, exhibit a significant degree of genomic heterogeneity. There are at least four distinct simian HAVs differing from each other and from all human HAV strains. It is suggested that each virus is native to a given species reflecting evolutionary relationships among HAVs and their hosts in the order of Primates.

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

Recent studies have documented a considerable degree of genetic divergence among wild-type hepatitis A virus (HAV) strains recovered from different geographical locations. Human HAV strains can be grouped into four genotypes (I, II, III and VII) and unique simian strains belong to three additional genotypes (IV, V and VI). Between each of these genotypes, the nucleotide sequence varies at 15-25% of base positions in the P1 region. Despite this, there is good evidence that most, if not all, human strains of HAV are closely related antigenically. In contrast, although simian strains recovered from Old World monkeys are cross-reactive in immunoassays employing polyclonal antibodies, these strains have significant antigenic differences from human HAV strains. Nonetheless, because biological differences in the host range of these strains apparently preclude significant human infection, this is unlikely to pose a problem in controlling HAV infections with active immunization. Inactivated and attenuated vaccines produced from genotype I human strains (HM175 or CR326) are likely to provide protection against all relevant human HAV strains.

Properties and classification of hepatitis A virus

Hepatitis A virus (HAV) is a member of the picornavirus family. It was first provisionally classified as enterovirus 72, but subsequent determinations of its nucleotide and amino acid sequences showed them to be sufficiently distinct to assign the virus to a new genus. Heparna-virus (Hep-A-RNA-virus) has been suggested as the genus name. HAV shares the key properties of the picornavirus family: an icosahedral particle 28 nm in diameter with cubic symmetry, composed of 30% RNA and 70% protein. The genome is single-stranded 7.48 kb RNA, linear and positive-sense. Like other picornaviruses, HAV possesses four major polypeptides cleaved from a large precursor polyprotein. The surface proteins VP1 and VP3 are major antibody-binding sites. The internal protein VP4 is much smaller than the VP4s of other picornaviruses. As other picornaviruses, HAV has no envelope and replicates in the cytoplasm. HAV is stable to treatment with either and acid, and is much more heat-resistant than other picornaviruses. It withstands 60 degrees C for 1 h. MgCl2 stabilizes the virus to withstand temperatures up to 80 degrees C. The relative resistance of HAV to disinfection indicates a need for extra precautions in dealing with hepatitis patients and their products. Only one serotype is known. There is no antigenic cross-reactivity with other hepatitis viruses. HAV initially was identified in stool and liver preparations by employing immune electron microscopy as the detection system. Chimpanzees and marmoset monkeys are susceptible to HAV. HAV has been cultivated serially in primary explant cultures of adult marmoset livers and in cell lines of primate origin.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies in monkeys of attenuated hepatitis A variants

Three HAV variants, H2M20(35 degrees C), H2M20(35 degrees C) and H2M20K5(32 degrees C), were developed by passage in different tissue culture cells and at different temperatures. Virulence for monkeys was assessed by inoculating each of the variants into four monkeys. Weekly bleeding through 16 weeks post-inoculation was assayed for anti-HAV titers and SGPT as well as LDH5 activities. And in some monkeys liver biopsies were also studied. Seroconversion was induced in all of the inoculated monkeys. The anti-HAV titers tested at 16 weeks post-inoculation were: 40-640 with H2M20(35 degrees C), 40-160 with H2M20(32 degrees C) and 20-40 with H2M20K5(32 degrees C). These variants showed different levels of virulence/attenuation for monkeys. Variant H2M20(35 degrees C) showed no evidence of attenuation, variant H2M20(32 degrees C) retained slight virulence and variant H2M20K5(32 degrees C) showed no evidence of virulence for monkeys. Criteria are proposed for assay of HAV virulence tested in monkeys.

Hepatitis A virus replication in tamarins and host immune response in relation to pathogenesis of liver cell damage

Hepatitis A virus (HAV) shedding in the faeces, appearance of HAV-Ag (antigen) in the liver, and development of humoral immunity to HAV have been studied in experimentally infected tamarins. The appearance of liver damage measured by transaminase elevation and histology, in relation to the above variables, suggests that the virus is not cytopathic and the immune system contributes to the production of liver cell damage. Preliminary data suggest that HAV replication may occur in the mucosa of the small intestine and in the liver.

Taxonomic classification of hepatitis A virus

Sufficient data have accumulated to permit the ICTV Ad Hoc Study Group on the Taxonomy of Hepatitis Viruses to recognize hepatitis A virus as a picornavirus. Within the family Picornaviridae, hepatitis A virus closely resembles members of the genus Enterovirus.

[Viral hepatitis with clinical and epidemiological manifestations similar to hepatitis A but of a different etiology]

A case of viral hepatitis in man, appearing as the result of infection caused by pooled concentrated suspensions of fecal samples collected from patients having had repeated hepatitis infection during the period of 1-2 years, is described. Though this infection was similar to hepatitis A in many clinical and epidemiological signs, the possibility of its etiologic relationship with hepatitis virus A was positively excluded; there was also no evidence of the participation of hepatitis virus B in the process. Immunoelectron microscopy of excretions collected at the acute stage of the disease revealed the presence of spherical viral particles 27-30 nm in diameter. Antibodies capable of reacting with these particles were detected in the sera of patients having had 2 kinds of hepatitis and in the sera of patients having the 1 kind of hepatitis in the focus of infection where repeated cases of hepatitis had been observed. No such antibodies were found in the sera of patients with hepatitis A alone and in the set of standard sera specific to viruses causing hepatitis A and hepatitis non A, non B. The authors believe that 2 kinds of hepatitis with the fecal-oral mechanism of transmission exist and propose to name their causative agents hepatitis viruses A, type 1 and type 2.

Evidence that the genome of hepatitis A virus consists of single-stranded RNA

Nucleic acid was extracted from purified hepatitis A virus, radiolabeled with 125I, and shown to consist of single-stranded RNA which sediments at 35S and contains sequences of polyadenylic acid. These findings are consistent with hepatitis A virus being a member of the genus Enterovirus within the family Picornaviridae.

Characterization and classification of virus particles associated with hepatitis A. II. Type and configuration of nucleic acid

Virus particles banding at 1.34 g/ml in CsCl and sedimenting at 160S in sucrose gradients were isolated from fecal specimens of patients suffering from hepatitis. In the presence of 4 M urea and about 90% formamide, these particles released linear nucleic acid molecules of the kinked appearance characteristic of single-stranded RNA or single-stranded DNA. They could be distinguished from the nucleic acid of phage lambda added to the preparation as a marker for double-stranded configuration. Experiments in which the virus particles under investigation were incubated at pH 12.9 at 50 degrees C for 30 min revealed that their nucleic acid molecules were hydrolyzed as readily as the RNA genome of poliovirus type 2 analyzed in parallel. Both the single-stranded DNA of phage phiX174 and that of parvovirus LuIII, however, proved unaffected by this treatment, and the double-stranded DNA of phage lambda was denatured to single-stranded molecules. It was concluded, therefore, that the virus of human hepatitis A contains a linear genome of single-stranded RNA and has to be classified with the picornaviruses.

Characterization and classification of virus particles associated with hepatitis A. I. Size, density, and sedimentation

Virus-like particles were purified from stools of patients in an epidemic of hepatitis A in Germany. When reference MS-1 chimpanzee pre-inoculation and convalescent sera were used, the close serological relationship of the purified particles to well-known isolates of hepatitis A could be established. On the other hand, the physicochemical characteristics of the particles were determined in parallel to the characteristics of a marker parvovirus (LuIII) and a marker picornavirus (poliovirus type 2). It could be shown that the majority of the hepatitis A-associated particles band at 1.34 g/ml in CsCl and, like poliovirus, sediment at about 160S. In addition, a distinct hepatitis A antigen was observed, which banded at 1.305 g/ml and sedimented between 50 and 90S. A further component accumulated in the density range of between 1.38 and 1.44 g/ml. However, it seemed to be rather labile. Upon reisolation from CsCl and sedimentation in sucrose, it resolved into a 160S, a 90 to 100S, and a 50S form. The size of the 160S particles (27 to 29 nm) could be readily distinguished from that of the parvovirus (22 to 24 nm). It is concluded, therefore, that hepatitis A-associated virus particles are more likely to be classified with the picornaviruses than with the parvoviruses.

Biochemical and biophysical characterization of light and heavy density hepatitis A virus particles: evidence HAV is an RNA virus

Heavy density HAV was also shown to be sensitive to low concentrations of RNase. The results of these biophysical and biochemical studies strongly support the notion HAV is an enterovirus.

The polypeptides of hepatitis A virus

Hepatitis A virus was purified from fecal specimens obtained from 3 patients with naturally acquired hepatitis A, by a process of differential centrifugation, chloroform extraction, column chromatography, and isopycnic ultracentrifugation. Analysis of purified virus by discontinuous SDS-PAGE revealed three major polypeptides with molecular weights of 34,000, 25,500, and 23,000 daltons. These polypeptides appear to be specific for hepatitis A virus and have similar molecular weights to three of the four major polypeptides reported for members of the genus Enterovirus within the family Picornaviridae.

Multiple buoyant densities of hepatitis A virus in cesium chloride gradients

Hepatitis A virus (HAV) recovered from stools of human cases of hepatitis A and from stools of chimpanzees experimentally infected with HAV was shown to possess multiple buoyant densities in CsCl gradients. The greatest proportion of HAV was most frequently found at a buoyant density of 1.32-1.34 g/cm3, however, large proportions of HAV were also frequently found at higher densities, including 1.36-1.37, 1.40-1.42, and 1.45-1.48 g/cm3. These findings are consistent with the notion that HAV may be a parvovirus.

Viral hepatitis--a primer: 1. Epidem.iology

Hepatitis A is most often transmitted by the fecal-oral route under conditions of crowding, poor hygiene, and prolonged exposure to infected persons. Direct spread of hepatitis B via person-to person contact has only recently been proved. Hepatitis B is usually transmitted indirectly proved. Hepatitis B is usually transmitted indirectly by percutaneous routes, and the increase in drug abuse has brought about a change in its epidemiologic pattern.

Hepatitis A. Perspectives and recent advances

The basis for the epidemiologic and etiologic differentiation of two major forms of viral hepatitis, hepatitis A and B, was established in a series of studies undertaken between 1930 and 1970. Final recovery and visualization of the presumed etiologic agent of hepatitis A was not, however, accomplished until the technique of immune electron microscopy was applied to the examination of specimen materials collected from individuals in the early acute stages of infection. Morphologically homogeneous virus-like particles of 27 nm diameter have now been recovered from stools of patients with hepatitis A ill from a variety of sources. Antibody to these particles has been shown to develop during the course of infection with hepatitis A but not with hepatitis B and disease has been induced in nonhuman primates inoculated with purified particle containing fractions. The classification of hepatitis A virus has not been conclusively established, but it would appear to be either a parvovirus or an enterovirus.

Biophysical and biochemical properties of CR326 human hepatitis A virus

CR326 human hepatitis A virus purified by isopycnic banding from infected marmoset sera was shown to consist of 27 mmu spherical particles on electron microscopic examination. The particles were identified as hepatitis A virus by tests by infectivity and by specific neutralization of infectivity with convalescent human hepatitis A serum. Also, identical 27 mmu viruses in liver extracts gave specific reactions with hepatitis A antisera when tested by immune electron microscopy. The buoyant density of the virus in CsCl was 1.34 and it was heat (60 C), ether, and acid stable but was destroyed by heat (100 C), formalin (1:4000), and ultraviolet irradiation. Electron microscopic studies of sections of infected marmoset liver showed intracytoplasmic virus particles, usually in vesicles. Presumptive findings for RNA, together with the intracytoplasmic location of the virus, indicated the virus to be of RNA-type. The attributes of the virus indicate it is closely related to the enterovirus family and not to hepatitis B virus.

Review of infectivity studies in nonhuman primates with virus-like particles associated with MS-1 hepatitis

Using the technique of immune electron microscopy we have conducted hepatitis A infectivity studies in marmoset monkeys and chimpanzees. Marmosets inoculated with human serum containing the MS-1 strain of hepatitis A virus have developed hepatitis and seroconverted to 27 nm virus-like particles isolated from stools of humans in the early acute stages of hepatitis. Similar results have been observed through several marmoset subpassages, and the virus-like particles have been recovered from the liver of animals in the acute phase of hepatitis. Chimpanzees inoculated with stool filtrates containing the virus-like particles develop hepatitis with concomitant excretion of the particles in early acute phase stools and subsequent development of serum antibody to the particles. These studies provide evidence that the above particles constitute the virus of hepatitis A of the MS-1 prototype.

Hepatitis in marmosets

Some species of marmosets are susceptible, not only by parenteral inoculation but also by oral exposure, to human hepatitis A virus present in sera or feces. The stools of animals inoculated parenterally or orally contained fecal antigen during certain times of the incubation period and the early, acute phase of the disease; viruslike particles were present in feces of orally infected animals and such feces were infectious when inoculated into marmosets. The fecal antigen crossreacted both with the fecal virus particles and the immune-adherence antigen (see also papers by Purcell et al and Hilleman et al). The MS-1 and CR-326 strains of hepatitis A appeared antigenically similar or identical whereas the GB strain was antigenically different and may be associated with the recently defined type of hepatitis termed hepatitis C or hepatitis non-A/non-B. On repeated challenge hyperegic responses with diffuse liver cell necrosis occurred in some immune animals and this phenomenon must be taken into account in any future vaccination studies.