Hepatitis E virus in Nepal: similarities with the Burmese and Indian variants

Gouvêa, Vera; Snellings, Norma J.; Cohen, Stuart J.; Warren, Richard L.; Myint, Khin Saw Aye; Shrestha, Mrigendra P.; Vaughn, David W.; Hoke, Charles H.; Innis, Bruce L.

doi:10.1016/s0168-1702(97)00112-3

Cited by 26 publications

(18 citation statements)

References 25 publications

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“…A 405-nucleotide fragment from the 3Ј end of the capsid gene was used to search for related virus sequences in GenBank (NCBI). Sequence alignments confirmed that the DNA sequence amplified from the rodents was an HEV sequence and that it shared 95 to 96% nucleotide sequence identity and 98% amino acid sequence identity with two human HEV strains recovered from Nepalese hepatitis E patients in 1987 and 1994 (14). On the other hand, the rodent HEV sequence had less homology with other human or swine HEV isolates (Table 3).…”

Section: Resultsmentioning

confidence: 75%

“…These rodent and human viruses have capsid gene sequences with 95 to 96% nucleotide homology and 98% amino acid homology. Moreover, a previous phylogenetic analysis based on capsid gene sequences found that human HEV isolates from the Kathmandu Valley collected between 1991 and 1995 were indistinguishable (14). This means that the HEV isolates derived from rodents in 1996 could have shared a common ancestor with human strains isolated between 1987 and 1995 by means of cross-species transmission.…”

Section: Discussionmentioning

confidence: 96%

“…Reverse transcription-PCR (RT-PCR) was performed as described previously (16). The sequences of primer sets were derived from ORF-2 of HEV Burma, which shares 95% nucleotide sequence identity with a previously characterized human HEV strain from Nepal (14). The primers used for the first-round PCR were SF1 (sense) (nucleotides 6578 to 6596; 5Ј-GCCGAGTATGACCAGTCCA-3Ј) and SR1 (antisense) (nucleotides 7127 to 7107; 5Ј-ACAACTCCCGAGTTTTACCC-3Ј).…”

Section: Methodsmentioning

confidence: 99%

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Evidence that Rodents Are a Reservoir of Hepatitis E Virus for Humans in Nepal

Innis

Shrestha

et al. 2002

J Clin Microbiol

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Hepatitis E virus (HEV) is an important cause of enterically transmitted hepatitis in developing countries. Sporadic autochthonous cases of hepatitis E have been reported recently in the UnitedStates and other industrialized countries. The source of HEV infection in these cases is unknown; zoonotic transmission has been suggested. Antibodies to HEV have been detected in many animals in areas where HEV is endemic and in domestic swine and rats in the United States. There is evidence supporting HEV transmission between swine and humans. Nevertheless, HEV has not been detected in wild rodents. We tested murid rodents and house shrews trapped in Nepal's Kathmandu Valley, where hepatitis E is hyperendemic, for HEV infection. The most commonly trapped species was Rattus rattus brunneusculus. Serum samples from 675 animals were tested for immunoglobulin G against HEV by enzyme-linked immunosorbent assay; 78 (12%) were positive, indicating acute or past infection. Antibody prevalence was higher among R. rattus brunneusculus and Bandicota bengalensis than in Suncus murinus. Forty-four specimens from 78 antibody-positive animals had sufficient residual volume for detection of HEV RNA (viremia) by reverse transcription-PCR. PCR amplification detected four animals (9%; three were R. rattus brunneusculus and one was B. bengalensis) with viremia. Phylogenetic analysis of the four genome sequences (405 bp in the capsid gene) recovered showed that they were identical, most closely related to two human isolates from Nepal (95 and 96% nucleotide homology, respectively), and distinct from HEV sequences isolated elsewhere. These data prove that certain peridomestic rodents acquire HEV in the wild and suggest that cross-species transmission occurs, with rodents serving as a virus reservoir for humans.Hepatitis E virus (HEV) is the most important cause of acute hepatitis in many developing countries of Asia, the Middle East, and Africa as well as in Mexico (29). In industrialized countries, autochthonous hepatitis E was thought to be absent. Yet recently, a few autochthonous hepatitis E cases from the United States and other industrialized countries have been reported (12,13,18,22,24,31,32,39).HEV transmission is thought to occur primarily by the fecaloral route; water-borne epidemics are characteristic (1,28,29). Therefore, the occurrence of isolated hepatitis E cases can be explained only by silent transmission of HEV among human or animal case contacts.The occurrence of autochthonous hepatitis E in industrialized countries has focused renewed attention on the question of whether hepatitis E is a zoonosis (29; M. Favorov, O. Nazarova, and H. S. Margolis, presented at the Second International Conference on Emerging Zoonoses, Strasbourg, France, 5 to 9 November 1998). Antibodies to HEV have been found in cows, sheep, goats, chickens, water buffaloes, swine, wild rats, mice, and monkeys from areas where hepatitis E is endemic and in domestic swine and rats in the United States (3,9,10,20,21,26,37). Successful transmission of human HEV...

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Section: Resultsmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

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Evidence that Rodents Are a Reservoir of Hepatitis E Virus for Humans in Nepal

Innis

Shrestha

et al. 2002

J Clin Microbiol

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“…Considering the transient occurrence of the acute markers of hepatitis viruses, the possibility that the higher percentage of non-A to E cases observed in our studies might be attributed in part to higher false negatives cannot be ruled out. As for other possibilities, the involvement of a third, previously unrecognized, enterically transmitted hepatitis agent, whose existence was suggested by Arankalle et al (1994), and non-viral agents such as Gram-negative bacilli that are known to cause hepatitis (El-Newihi et al, 1996), need to be taken into consideration in some patients with acute hepatitis of unknown aetiology, since the clinical picture, age distribution and seasonal distribution of patients with non-A to E hepatitis in Nepal were similar to those of patients with hepatitis E (data not shown Gouvea et al (1997Gouvea et al ( , 1998 and Shrestha et al (2003), but HEV 1c had not been identified in Nepal. To date, HEV 1c has been isolated in India and mainland China (Wang et al, 1999), suggesting that the 1c strain(s) was imported from India or China to Nepal in 1997 or before, but was taken over by the co-circulating 1a strains in 1999.…”

Section: Discussionmentioning

confidence: 94%

Genetic changes in hepatitis E virus of subtype 1a in patients with sporadic acute hepatitis E in Kathmandu, Nepal, from 1997 to 2002

Shrestha¹,

Tsuda

Nishizawa

et al. 2004

Journal of General Virology

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“…22 There was no report of mutation of HEV in Nepal. 23 The study of genetic changes based on observation of 412-nt sequences within ORF2 of HEV among 116 HEV-viremic samples from Nepal obtained at different periods from 1997 to 2002 showed no significant amino acid substitution. 11 Further, only three out of 15 HE patients with SAHF were viremic and they all belonged to genotype 1.…”

Section: Thus the Question Arises What Is This Entity Called Sahf? Anmentioning

confidence: 99%