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Year : 2010  |  Volume : 132  |  Issue : 5  |  Page : 487-488

Studies of hepatitis E virus genotypes

Department of Life Science, Kyungwon University, Seongnam-Si, Kyeonggi-Do, 461-701, Korea

Date of Web Publication9-Apr-2011

Correspondence Address:
Yoon-Jae Song
Department of Life Science, Kyungwon University, Seongnam-Si, Kyeonggi-Do, 461-701
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Source of Support: None, Conflict of Interest: None

PMID: 21149996

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How to cite this article:
Song YJ. Studies of hepatitis E virus genotypes. Indian J Med Res 2010;132:487-8

How to cite this URL:
Song YJ. Studies of hepatitis E virus genotypes. Indian J Med Res [serial online] 2010 [cited 2020 Jun 5];132:487-8. Available from:

Hepatitis E virus (HEV) is the major aetiological agent of acute viral hepatitis and a member of the Hepeviridae family [1] . It has a single-stranded, positive RNA genome of 7.3 kb in length and contains 5' untranslated region (UTR), three open reading frames (ORF 1, 2 and 3) encoding a non-structural protein, a capsid protein and a non structural phosphoprotein, respectively and 3' UTR. Since there is no efficient cell culture system for HEV, detailed mechanisms of virus life cycle and pathogenesis are unclear.

A molecular phylogenetic analysis classifies HEV into four major genotypes [2] . Genotype 1 is found in developing countries in Asia and Africa, genotype 2 is isolated in Mexico and Africa, genotype 3 is distributed worldwide including developed countries, and genotype 4 is reported in Asia [2] . Genotype 3 and 4 are further divided into 10 (3a-3j) and 7 (4a-4g) subgenotypes, respectively, and found in both human and swine. Although the severity of HEV-associated acute hepatitis is believed to rely on the status of the host's immune system, viral factors may also play important roles in the pathogenesis of the disease. Indeed, genotype of HEV contributes to the pathogenesis of HEV-associated hepatitis [3] . Genotype 4 HEV infected patients showed more severe form of the viral hepatitis than genotype 3 HEV infected patients [2] . Thus, the genetic changes in HEV genotypes may affect the effectiveness of virus transmission and, in turn, the severity of HEV-associated hepatitis. To further determine the transmission and pathogenesis of HEV, molecular epidemiological study of HEV genotypes are needed.

HEV is spread via the faecal-oral route and transmitted through water or raw food contaminated with faeces [1] . HEV is highly prevalent in developing countries with poor sanitation and hygiene. HEV endemic areas include central and south East Asia, northern and sub-Saharan Africa, the Middle East and Mexico [2] . In developed countries, sporadic HEV-associated hepatitis was diagnosed in person with a history of travel to HEV endemic regions. However, several cases of HEV-associated hepatitis were reported in developed countries among people who had no history of travel to endemic areas [4],[5],[6],[7] . Although the cause of these incidents still needs to be determined, the zoonotic transmission of HEV, especially genotypes 3 and 4, was proposed because non-human primates, swine, sheep, cows, goats and rodents may serve as reservoirs for HEV [8] . Swine is considered to be a major reservoir of HEV infection because human HEV can experimentally infect swine and HEV isolates from human are genetically related to those from swine in the same geographic area [8],[9],[10],[11] . However, India has been an exception to this hypothesis because genotype 1 HEV is mainly circulating in human and genotype 4 HEV in swine in this region [12],[13] .

In this issue, Begum et al [14] report a study investigating HEV genotype circulating in swine population from north India. As previously reported in other regions of India, genotype 4e HEV is predominant in swine from the region although the sample size test in their study is relatively small (67 samples). Interestingly, these HEV isolates from swine are genetically related to human isolates of India from 71.6 to 74.6 per cent indicating that a zoonosis may be a mode of transmission for HEV also in India. Indeed, a case of zoonotic transmission of HEV genotype 4 was reported in a patient with severe hepatitis and a history of travel to India [15] . This report further strengthens the hypothesis that the zoonosis is the mode of transmission for HEV. More molecular phylogenic analysis of HEV genotypes circulating in human and swine population in India is thus required to delineate the mode of HEV transmission and the evolution of new emerging HEV genotype subgroups.

   References Top

1.Chandra V, Taneja S, Kalia M, Jameel S. Molecular biology and pathogenesis of hepatitis E virus. J Biosci 2008; 33 : 451-64.  Back to cited text no. 1
2.Okamoto H. Genetic variability and evolution of hepatitis E virus. Virus Res 2007; 127 : 216-28.  Back to cited text no. 2
3.Mizuo H, Yazaki Y, Sugawara K, Tsuda F, Takahashi M, Nishizawa T, et al. Possible risk factors for the transmission of hepatitis E virus and for the severe form of hepatitis E acquired locally in Hokkaido, Japan. J Med Virol 2005; 76 : 341-9.  Back to cited text no. 3
4.Brost S, Wenzel JJ, Ganten TM, Filser M, Flechtenmacher C, Boehm S, et al. Sporadic cases of acute autochthonous hepatitis E virus infection in Southwest Germany. J Clin Virol 2010; 47 : 89-92.  Back to cited text no. 4
5.Fogeda M, Avellon A, Cilla CG, Echevarria JM. Imported and autochthonous hepatitis E virus strains in Spain. J Med Virol 2009; 81 : 1743-9.  Back to cited text no. 5
6.Kwo PY, Schlauder GG, Carpenter HA, Murphy PJ, Rosenblatt JE, Dawson GJ, et al. Acute hepatitis E by a new isolate acquired in the United States. Mayo Clinic Proc 1997; 72 : 1133-6.  Back to cited text no. 6
7.Takahashi M, Nishizawa T, Yoshikawa A, Sato S, Isoda N, Ido K, et al. Identification of two distinct genotypes of hepatitis E virus in a Japanese patient with acute hepatitis who had not travelled abroad. J Gen Virol 2002; 83 : 1931-40.  Back to cited text no. 7
8.Bihl F, Negro F. Hepatitis E virus: a zoonosis adapting to humans. J Antimicrob Chemother 2010; 65 : 817-21.  Back to cited text no. 8
9.Nishizawa T, Takahashi M, Mizuo H, Miyajima H, Gotanda Y, Okamoto H. Characterization of Japanese swine and human hepatitis E virus isolates of genotype IV with 99 % identity over the entire genome. J Gen Virol 2003; 84 : 1245-51.  Back to cited text no. 9
10.Song YJ, Jeong HJ, Kim YJ, Lee SW, Lee JB, Park SY, et al. Analysis of complete genome sequences of swine hepatitis E virus and possible risk factors for transmission of HEV to humans in Korea. J Med Virol 2010; 82 : 583-91.  Back to cited text no. 10
11.Suwannakarn K, Tongmee C, Theamboonlers A, Komolmit P, Poovorawan Y. Swine as the possible source of hepatitis E virus transmission to humans in Thailand. Arch Virol 2010; 155 : 1697-9.  Back to cited text no. 11
12.Arankalle VA, Chobe LP, Joshi MV, Chadha MS, Kundu B, Walimbe AM. Human and swine hepatitis E viruses from Western India belong to different genotypes. J Hepatol 2002; 36 : 417-25.  Back to cited text no. 12
13.Arankalle VA, Lole KS, Deshmukh TM, Chobe LP, Gandhe SS. Evaluation of human (genotype 1) and swine (genotype 4)-ORF2-based ELISAs for anti-HEV IgM and IgG detection in an endemic country and search for type 4 human HEV infections. J Viral Hepat 2007; 14 : 435-45.  Back to cited text no. 13
14.Begum N, Polipalli SK, Husain SA, Kar P. Molecular analysis of swine hepatitis E virus from north India. Indian J Med Res 2010; 132 : 504-8.  Back to cited text no. 14
15.Rolfe KJ, Curran MD, Mangrolia N, Gelson W, Alexander GJ, L'Estrange M, et al. First case of genotype 4 human hepatitis E virus infection acquired in India. J Clin Virol 2010; 48 : 58-61.  Back to cited text no. 15


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