Phylogenetic analysis of hepatitis E virus isolates from India (1976-1993)

Type-IV Indian swine HEV infects rhesus monkeys

In contrast to countries reporting zoonotic spread of hepatitis E virus (HEV), distinct genotypes circulate in humans (genotype 1) and pigs (genotype 4) from India indicating rarity of such spread. Pigs were refractory to human HEV. As rhesus is an excellent animal model for human HEV, an attempt was made to infect rhesus monkeys with swine HEV. Experimental infection of both the rhesus monkeys with swine-HEV as evidenced by seroconversion to anti-HEV antibodies and presence of viraemia suggests possibility of human infections or differential susceptibility. Comparison of Open Reading Frame-2 and hypervariable regions of HEV genomes showed identity of swine and monkey-derived HEV.

Locally acquired hepatitis E virus infection, El Paso, Texas

Hepatitis E virus (HEV) is an enterically transmitted RNA virus that causes both epidemic and sporadic cases of acute hepatitis. Despite sero-surveys showing antibody to HEV in up to 36% of the US population, acute hepatitis E has been reported among individuals with no history of international travel only three times in the United States. We report a case of apparently locally-acquired hepatitis E that occurred in El Paso, Texas that was 98% similar to a previously isolated HEV found in swine in the United States. Like the three previous cases, a thorough investigation found no conclusive sources of infection. Active case surveillance found no additional cases.

Comparison of real-time reverse transcriptase-polymerase chain reaction and nested or commercial reverse transcriptase-polymerase chain reaction for the detection of hepatitis E virus particle in human serum

Hepatitis E virus (HEV) was originally identified as the causative agent of enterically transmitted non-A, non-B hepatitis. The virus is the 7.5-kb single-stranded positive RNA virus and has been classified in the genus Herpevirus [corrected] of the [corrected] Herpeviridae [corrected] Recently, HEVs were identified from several countries worldwide from human and animals including swine. Studies on the genomic analysis of HEV isolates and seroprevalence of anti-HEV antibodies suggested that HEV has been considered as a potent zoonotic agent. The HEV infection has been diagnosed by detection of anti-HEV antibodies or virus by using reverse transcriptase-polymerase chain reaction (RT-PCR) methods in the blood or feces. However, these diagnostic methods were not quantitative and not enough to diagnose small amounts of target molecules. Moreover, these methods were not adequate during the incubation period or early acute phase. To overcome these problems, real-time RT-PCR method was developed with a cloned viral DNA and in vitro transcribed cRNA in this study. The sensitivity of the reaction was 1.68 x 10(1) copies per reaction. Correlation coefficient values of the reactions in the repeated experiments were over 0.99. Ranges of slopes and coefficient variation values were from 3.341 to 3.435 and from 1.20 to 5.98, respectively. In comparison of the real-time PCR with nested or commercial RT-PCR, HEV particles could be detected in the negative samples, which were determined by conventional nested RT-PCR.

Phylogenetic analysis of hepatitis E virus isolates in southern China (1994-1998)

BACKGROUND

We have previously reported the identification of divergent hepatitis E virus (HEV) isolated (G9, G20 and 93G) in Guangzhou, a city in southern China. They are now recognised as a new HEV subgenotype in the world. However, the relatedness and significance of these novel isolates in sporadic HEV infection in southern China is still unclear.

OBJECTIVES

To perform phylogenetic analysis of nucleotide sequences from 41 HEV isolates in southern China from 1994 to 1998.

STUDY DESIGN

The partial nucleotide sequence of the HEV isolates were determined and compared with reported sequences in the GenBank. Their relatedness was analysed using computer software.

RESULTS

The majority of the HEV isolates, 39 out of 41, were found to belong to the Burmese-like isolates (genotype 1). The other two belonged to the Guangzhou-like isolates. The latter were only found in the samples collected in 1994. They, together with the G9 isolate, form a unique tree located between genotype 1 and genotype 4 (divergent HEV strains from northern China and Taiwan) on the phylogenetic tree.

CONCLUSION

Our results suggest that the Burmese-like isolates are the main causative agents of sporadic HEV infection in southern China. The Guangzhou-like isolates, which appeared transiently in 1994, did not seem to adapt to the environment and have caused no sporadic infection since.

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.

Hepatitis E virus genotyping based on full-length genome and partial genomic regions

Some genomic regions for hepatitis E virus (HEV) genotyping have been reported to correlate well with the results from the phylogenetic analyses on the basis of the complete genome. However, few studies have systemically investigated the genomic regions for HEV genotyping using a combined phylogenetic and statistical approach. A consensus region for HEV genotyping has not been determined. In this study the nucleotide identities and genetic distances of 24 partial genomic regions and the complete genome sequences of 37 HEV strains were compared statistically. It was demonstrated with both one-way ANOVA and two-way ANOVA that only one genomic region in RNA-dependent RNA polymerase domain (4254-4560nt) for which there were no significant differences when compared with the full-length genome (P>0.05). The same four genotypes were identified by phylogenetic analysis based on this statistically predicted region identified as for the complete genome. RT-PCR amplification of HEV strains from all four genotypes confirmed conservation of the flanking primer sites of this region. Serum samples from 20 patients with a clinical diagnosis of hepatitis E were further analyzed by PCR using the same primers, 13 were positive and could be classified into genotype 4. These data strongly suggested that this newly identified region could be used for future HEV genotyping.

Epidemiology and genotypes of HEV in Wuhan

BACKGROUND

Understanding the genotype and clinical features of the hepatitis E virus (HEV) are important for understanding its characteristics, for evaluating region-specific diagnostic assays, and producing vaccines.

OBJECTIVES

To investigate the epidemiology and the genotypes of HEV among outpatients and inpatients in the Department of Infectious Diseases of Tongji Hospital in Wuhan, China.

METHODS

Clinical data were elicited from the hospital records of patients who were clinically diagnosed with acute hepatitis between January 2000 and August 2004 (4920 patients). Of these cases, 120 patients with anti-HEV-IgM, IgG-positive were selected to analysis. Conserved genomic sequences of open reading frame 2 (345 bp) in the HEV gene were detected using polymerase chain reaction, 25 of which were cloned and sequenced. Clustal X and Mega software were used for phylogenetic analysis of genotypes strains.

RESULTS

The HEV infection rate is gradually increasing in Wuhan. The number of male patients was 3.3-fold greater than the number of female patients found in clinical investigations. People aged 30-59 years are more susceptible to infection, and people are more susceptible in March-June. Twenty-five isolates shared the same genotype, genotype IV, with 82.61-98.55% nucleotide identity. This genotype had 76.52-81.74%, 70.43-73.04%, 76.52-81.16%, and 84.35-88.70% homology with the nucleotide sequence of HEV genotypes I-IV, respectively. Phylogenetic analysis suggested that these 25 isolates represented at least three different subtypes, but there were no significant differences found in the epidemiological features or liver function of patients with the three subtypes.

CONCLUSIONS

HEV sequences isolated from patients in Wuhan belong to different subtypes of HEV genotype IV.

Identification of novel human hepatitis E virus (HEV) isolates and determination of the seroprevalence of HEV in Korea

Hepatitis E virus (HEV) was originally identified as the causative agent of enterically transmitted non-A, non-B hepatitis. Recently, HEV isolates were subsequently identified in humans and swine in many countries, including Korea. Also, public concerns regarding HEV as a potential zoonotic agent have been increasing. Therefore, we attempted to identify HEV from Korean sera and compare the nucleotide sequences with those of previously identified HEV isolates from other countries. In our study, viral RNA was purified from 568 human sera collected from different regions of Korea. Nested PCR and reverse transcriptase PCR were developed based on the nucleotide sequences of open reading frame 2 (ORF 2) of U.S. and Japanese HEV isolates from humans and Korean HEV isolates from swine. After amplification of the HEV ORF 2 gene from 14 serum samples that were collected mainly from rural areas (2.64% prevalence of HEV viremia), the gene was cloned and sequenced. The isolates were classified into seven different strains, all of which belonged to genotype III. The human isolates we identified were closely related to three Korean swine isolates, with 99.2 to 92.9% nucleotide sequence homology. Our isolates were also related to the Japanese and U.S. HEV isolates, with 99.6 to 97.9% amino acid sequence homology. Human sera were collected from 361 individuals from community health centers and medical colleges. With respect to seroprevalence, 11.9% of the Korean population had anti-HEV immunoglobulin G (IgG). In individuals ranging in age from 40 to over 60 years, the prevalence of anti-HEV IgG was demonstrated by a seroprevalence of almost 15%, especially among populations in rural areas. This is the first report on the identification of human HEV in Korea. Overall, this study demonstrates that subclinical HEV infections may prevail in human populations in Korea and that there is a strong possibility that HEV is a zoonotic agent.

Evidence for hepatitis E virus quasispecies

The genetic diversity of hepatitis E virus (HEV) has been extensively analysed during the last decade. Most sporadic and epidemic HEV strains are distributed into genotypes or groups. Nevertheless, few studies have looked at the polymorphism of HEV strains isolated from a given outbreak. A serum bank collected in Tanefdour, Algeria, during an acute hepatitis epidemic (1986-1987), retrospectively confirmed as hepatitis E, was analysed. Of the 69 serum samples collected within an 8-week period, 23 were positive for both partial ORF1 (replicase gene) and ORF2 (capsid gene) sequences. Inter- and intra-patient diversities were assessed by RFLP, and by sequencing a 448 bp sequence corresponding to ORF2. RFLP analysis distinguished three profiles: A (18/23), B (3/23) and C (2/23). Most isolates (18/23) shared 99.7-100 % sequence identity and the remainder showed 1-1.3 % divergence. HEV intra-patient diversity was studied using 12 isolates (seven displaying the major RFLP profile and five displaying minor RFLP profiles). For 9 of 12 isolates, additional intra-patient heterogeneity was revealed by RFLP analysis of 100 clones from each isolate and sequence diversity ranging from 0.11 to 3.4 %. These data strongly support the quasispecies organization of HEV during epidemics and could explain the adaptable behaviour of the virus in the host-pathogen interrelations.

Hepatitis E Vaccines

Hepatitis E accounts for the major part of enterally transmitted non-A, non-B hepatitis worldwide. Its agent, the hepatitis E virus (HEV), is a small, single-stranded RNA virus. Only one serotype of HEV is recognised. Infection results in protective immunity with long-lived neutralising antibodies. In developing countries with poor sanitary conditions and high population density, hepatitis E causes water-borne epidemics with substantial mortality rates in pregnant women. In addition, more than 50% of cases of acute hepatic failure and sporadic acute hepatitis are due to hepatitis E. The overall prevalence rates of antibodies to the HEV in populations native to these areas rarely exceed 25%. Hence, many individuals remain susceptible to hepatitis E infection, making hepatitis E an important public health concern. In this context, the development of an HEV vaccine is warranted. Because HEV does not grow adequately in cell cultures the development of a vaccine based on inactivated or attenuated whole-virus particles is not feasible. HEV vaccines currently under study are based on recombinant proteins derived from immunogenic parts of the HEV capsid gene. Other approaches such as DNA-based vaccines or transgenic tomatoes have also been developed. Several recombinant protein-based vaccines elicited neutralising antibodies and protective immunity in vaccinated non-human primates. One such vaccine has passed phase I trial and is currently under further evaluation in field trials. Even so, several questions remain to be answered before vaccination programmes could be implemented.

Identification of swine hepatitis E virus (HEV) and prevalence of anti-HEV antibodies in swine and human populations in Korea

The swine hepatitis E virus (HEV) is considered to be a new zoonotic agent due to its close genomic resemblance to the human HEV and its ability to infect nonhuman primates. Hepatitis caused by HEV infection has been a serious public health problem in developing countries. However, recent seroprevalence studies indicate that the HEV also circulates in industrialized countries. In this study, a nested reverse transcription (RT)-PCR was developed to detect a part of the swine HEV open reading frame 2. Three Korean isolates of swine HEV were identified in 128 swine sera (2.3% prevalence) by the nested RT-PCR method. They were isolated from 2- to 3-month old pigs showing an age-specific prevalence of the HEV viremia. A phylogenetic tree analysis with a number of swine and human HEV isolates indicated that all Korean isolates of the swine HEV belong to genotype III. They were closely related to the swine and human HEV isolates that were identified in the United States and Japan. In addition, they formed a distinct branch in genotype III, showing a 92.7 to 99.8% identity at their nucleotide sequences. The overall prevalence of anti-swine HEV antibodies in swine was 15%. Antibodies to the swine HEV were not detected in 1-month-old pigs. However, the anti-swine HEV antibodies appeared in pigs older than 1 month and also showed an age-specific prevalence. The antibody prevalence rates to the swine HEV were 6.0, 10.0, 36.0, and 25.0%, in 2-, 3-, 4-, and 5-to-7-month-old pigs, respectively. In addition, the seroprevalence in sows to the swine HEV was 8.8%. On the other hand, 18% of blood donors in Korea were found to be positive for anti-HEV antibodies. Overall, this study indicates that subclinical HEV infections may prevail in swine and human populations in Korea.

Swine HEV infection in south India and phylogenetic analysis (1985-1999)

Hepatitis E is endemic in India. It was recently noted that although all the Indian human hepatitis E virus (HEV) isolates (1976-2001) were placed in genotype I, the swine HEV recovered from western India (2000) belonged to genotype IV. This was in contrast to reports from the United States and Taiwan wherein both human and swine HEV belonged to the same genotype, i.e., genotypes III and IV, respectively. In order to validate these findings further, we retrospectively examined serum samples collected from pigs from southern India. Sequential serum samples from 45 (1985-1987) and 12 (1999) pigs from Karnataka state, south India, were screened for the presence of HEV RNA (nested PCR) and IgG-anti-HEV (ELISA). PCR products (Open Reading Frame-2 region) were sequenced and subjected to phylogenetic analysis. In this study, 42/45 (1985-1987) and 12/12 (1999) pigs showed seroconversion to IgG anti-HEV antibodies, with a mean age at seroconversion of 4.8 +/- 1.6 months. Four samples collected in 1999 and two samples collected during 1985 were HEV RNA positive. All swine HEV sequences clustered with genotype IV, demonstrating that swine HEV was prevalent among south Indian pigs for at least for 16 years and, similar to western India, belonged to genotype IV. Thus, genotype I and IV HEV continue to circulate in humans and pigs, respectively, from India. Whether swine HEV infects humans remains to be determined.

The putative capsid protein of the newly identified avian hepatitis E virus shares antigenic epitopes with that of swine and human hepatitis E viruses and chicken big liver and spleen disease virus

We recently identified a novel virus, designated avian hepatitis E virus (avian HEV), from chickens with hepatitis-splenomegaly (HS) syndrome in the USA. We showed that avian HEV is genetically related to swine and human HEVs. Here we report the antigenic cross-reactivity of the putative open reading frame 2 (ORF2) capsid protein of avian HEV with those of swine and human HEVs and the Australian chicken big liver and spleen disease virus (BLSV). The region encoding the C-terminal 268 amino acid residues of avian HEV ORF2 was cloned into expression vector pRSET-C. The truncated ORF2 protein was expressed in E. coli as a fusion protein and purified by affinity chromatography. Western blot analysis revealed that the avian HEV ORF2 protein reacted with antisera against the Sar-55 strain of human HEV and with convalescent antisera against swine HEV and the US2 strain of human HEV, as well as with antiserum against BLSV. Convalescent sera from specific-pathogen-free chickens experimentally infected with avian HEV also reacted with the recombinant capsid proteins of swine HEV and Sar-55 human HEV. Antisera against the US2 human HEV also reacted with recombinant ORF2 proteins of both swine HEV and Sar-55 human HEV. The antigenic cross-reactivity of the avian HEV putative capsid protein with those of swine and human HEVs was further confirmed, for the most part, by ELISA assays. The data indicate that avian HEV shares certain antigenic epitopes in its putative capsid protein with swine and human HEVs, as well as with BLSV. The results have implications for HEV diagnosis and taxonomy.

Polymerase chain reaction-based prevalence of hepatitis A, hepatitis E and TT viruses in sewage from an endemic area

BACKGROUND/AIMS

Hepatitis A and E viruses (HAV, HEV) are transmitted enterically and are highly endemic in India. This study aims to evaluate prevalence of these and TT virus (TTV) in the sewage.

METHODS

Influent and effluent samples from a sewage treatment plant from Pune, India were collected twice a week for 1 year and subjected to nested polymerase chain reaction (PCR) for the detection of HAV RNA, HEV RNA and TTV DNA. HAV and HEV PCR products were sequenced. Effluent samples were not collected for 5 months as the plant was non-functional.

RESULTS

The overall prevalence was 24.42% (21/86, HAV), 10.98% (9/82, HEV) and 12.7% (8/63, TTV). Prevalence of HAV was significantly higher than HEV (P=0.023). During summer months, significantly higher HAV RNA positivity was noted (P<0.01). A substantial reduction in HAV RNA positivity (15/48 vs. 2/48, P=0.0008) was recorded for treated sewage samples. However, HEV RNA or TTV DNA positivity did not reduce significantly. Of the 17 HAV and HEV RNA negative sewage samples concentrated using ultracentrifugation, 13 and none were positive for HAV and HEV RNA, respectively. Phylogenetic analyses grouped these viruses in IB and Ia, respectively, the genotypes most prevalent in India.

CONCLUSIONS

Sewage may play an important role in maintaining hyper-endemicity of these infections. Sustained efforts are obligatory to render sewage less/non-infectious.

Hepatitis E: an overview

The hepatitis E virus (HEV) is a non-enveloped, positive-sense, single-stranded RNA virus with icosahedral symmetry. Although it is related to the alpha-virus superfamily, the HEV is classified as a separate Hepatitis E-like viruses genus. Infection in humans occurs in sporadic and epidemic forms and can cause an acute, self-limited, icteric hepatitis. Recent studies indicate the existence of a reservoir in animals.

Spread of hepatitis E virus among different-aged pigs: two-year survey in Taiwan

Swine are reservoirs of hepatitis E virus (HEV). In this study, a 2-year survey of HEV in feces and sera of swine was conducted to determine if: 1) HEV has circulated among pigs for some time in Taiwan; 2) the spread of HEV among different-aged pigs; and 3) there exists HEV strains possibly imported through trading. From 1998-2000, 521 serum samples and 54 fecal specimens from pigs were examined by reverse transcription polymerase chain reaction. None of the 11 pigs in suckling stage (< 2 months) were serum HEV RNA positive. The highest viremia rate (4.5%) was in pigs of 2 months age, followed by 1.2% and 1.8% in pigs of growing (3-4 months) and finishing stages (5-6 months), and none in pigs older than 6 months. Viremia showed little variation in different years and areas. None of the 20 fecal samples from pigs in suckling stage were HEV RNA positive, whereas 9% of the 34 samples from pigs in growing or finishing stages were positive. Most swine HEV isolates in Taiwan clustered within the genotype 4, whereas the three HEV isolates cloned from pigs imported recently from the U.S. belonged to the genotype 3 HEV in the U.S. The results suggest that HEV may infect pigs at an early growing stage and spread unnoticed among pigs and possibly across countries through trading.

Human and swine hepatitis E viruses from Western India belong to different genotypes

BACKGROUND/AIMS

Hepatitis E is endemic in India. Earlier, we showed prevalence of IgG antibodies to hepatitis E virus (IgG-anti-HEV) in different animal species and inability of at least one human hepatitis E virus (HEV) strain to infect pigs. In the US where hepatitis E is not endemic in humans, zoonotic spread of HEV was suspected as swine and human HEV were closely related and cross-species infection was documented. The present study attempts to identify and partially characterize swine HEV from India.

METHODS

Serum samples from 284 pigs were screened for the presence of HEV-RNA (nested polymerase chain reaction; PCR) and IgG-anti-HEV (enzyme-linked immunosorbent assay; ELISA). PCR products (Open Reading Frame-2 region) were sequenced and subjected to phylogenetic analysis. Two sero-negative pigs were inoculated with swine HEV-positive serum pool.

RESULTS

ELISA and PCR positivity were 42.9 and 4.6%, respectively. All Indian swine HEV sequences clustered with genotype IV. Pigs could be experimentally infected with swine HEV.

CONCLUSIONS

Swine HEV circulates in Indian pigs. In contrast to US and Taiwan wherein both human and swine HEV isolates belong to same genotype, Indian human HEV isolates belong to genotype I whereas genotype IV circulates in swine. Though experimental infection with Indian swine HEV was possible, at least one human HEV strain could not infect pigs.

Genetic identification and characterization of a novel virus related to human hepatitis E virus from chickens with hepatitis-splenomegaly syndrome in the United States

Hepatitis-splenomegaly (HS) syndrome is an emerging disease in chickens in North America; the cause of this disease is unknown. In this study, the genetic identification and characterization of a novel virus related to human hepatitis E virus (HEV) isolated from bile samples of chickens with HS syndrome is reported. Based upon the similar genomic organization and significant sequence identity of this virus with HEV, the virus has been tentatively named avian HEV in order to distinguish it from human and swine HEV. Electron microscopy revealed that avian HEV is a non-enveloped virus particle of 30-35 nm in diameter. The sequence of the 3' half of the viral genome ( approximately 4 kb) was determined. Sequence analyses revealed that this genomic region contains the complete 3' non-coding region, the complete genes from open reading frames (ORFs) 2 and 3, the complete RNA-dependent RNA polymerase (RdRp) gene and a partial helicase gene from ORF 1. The helicase gene is the most conserved gene between avian HEV and other HEV strains, displaying 58-61% aa and 57-60% nt sequence identities. The RdRp gene of avian HEV shares 47-50% aa and 52-53% nt sequence identities and the putative capsid gene (ORF 2) of avian HEV shares 48-49% aa and 48-51% nt sequence identities with the corresponding regions of other known HEV strains. Phylogenetic analysis indicates that avian HEV is genetically related to, but distinct from, other known HEV strains. This discovery has important implications for HEV animal models, nomenclature and natural history.

Genetic heterogeneity of hepatitis E virus

Hepatitis E virus (HEV) infection has been considered a disease associated with developing regions and attributed to oral-fecal transmission due to inadequate sanitation. Several recent findings, however, have led to a new understanding of this virus. A number of novel isolates have been identified in patients with acute hepatitis from regions not considered endemic for HEV, and these individuals reported no recent travel to HEV endemic areas. In addition, a number of HEV-like sequences have also been isolated from swine worldwide, suggesting the potential of an animal reservoir. Although full-length sequence is available for some strains, the majority of HEV isolates have only been sequenced partially. Sequence comparisons and phylogenetic analyses were performed to determine the genotypic distribution of HEV isolates, based on the partial sequence data available. It has been suggested that HEV isolates segregate into four major genotypes based on full-length comparisons. These analyses, however, indicate that HEV may be distributed into at least nine different groups.

Virus-specific mRNA capping enzyme encoded by hepatitis E virus

Hepatitis E virus (HEV), a positive-strand RNA virus, is an important causative agent of waterborne hepatitis. Expression of cDNA (encoding amino acids 1 to 979 of HEV nonstructural open reading frame 1) in insect cells resulted in synthesis of a 110-kDa protein (P110), a fraction of which was proteolytically processed to an 80-kDa protein. P110 was tightly bound to cytoplasmic membranes, from which it could be released by detergents. Immunopurified P110 catalyzed transfer of a methyl group from S-adenosylmethionine (AdoMet) to GTP and GDP to yield m(7)GTP or m(7)GDP. GMP, GpppG, and GpppA were poor substrates for the P110 methyltransferase. There was no evidence for further methylation of m(7)GTP when it was used as a substrate for the methyltransferase. P110 was also a guanylyltransferase, which formed a covalent complex, P110-m(7)GMP, in the presence of AdoMet and GTP, because radioactivity from both [alpha-(32)P]GTP and [(3)H-methyl]AdoMet was found in the covalent guanylate complex. Since both methyltransferase and guanylyltransferase reactions are strictly virus specific, they should offer optimal targets for development of antiviral drugs. Cap analogs such as m(7)GTP, m(7)GDP, et(2)m(7)GMP, and m(2)et(7)GMP inhibited the methyltransferase reaction. HEV P110 capping enzyme has similar properties to the methyltransferase and guanylyltransferase of alphavirus nsP1, tobacco mosaic virus P126, brome mosaic virus replicase protein 1a, and bamboo mosaic virus (a potexvirus) nonstructural protein, indicating there is a common evolutionary origin of these distantly related plant and animal virus families.

Prevalence of anti-hepatitis E virus antibodies in different Indian animal species

Prevalence of IgG antibodies to hepatitis E virus (IgG-anti-HEV) was determined among different animal species from India. Seropositivity varied from 4.4% to 6.9% in cattle, 54.6-74.4% in pigs and 2.1-21.5% in rodents. Of the 44 dogs screened, 10 were positive (22.7%). None of the 250 goat sera tested were found to be anti-HEV positive. Among rodents, over 50% serum samples collected in 1985 from Bandicota bengalensis were positive for anti-HEV antibodies. No evidence of HEV infection was obtained following experimental inoculation of an Indian strain (AKL-90) of HEV into anti-HEV negative pigs and goats. The results document varied prevalence of anti-HEV antibodies in different animal species from India and of inability of Indian pigs and goats to support replication of at least one human strain of HEV.