Acute hepatitis E in India appears to be caused exclusively by genotype 1 hepatitis E virus
Hepatitis E is caused by infection with hepatitis E virus (HEV), which has four well-known genotypes. Genotypes 1 and 2 HEV have been reported from human cases in areas where the disease is highly endemic. By contrast, genotypes 3 and 4 HEV, which primarily infect several animal species worldwide, have been reported mainly from sporadic human cases in non-endemic areas such as Japan and high-income countries of Europe and North America. To determine whether genotype 3/4 HEV cause sporadic disease in India, a disease-endemic area, we determined HEV genotype in a group of patients with such disease.
A part of the HEV open reading frame (ORF) 1 was amplified and sequenced from sera of 74 patients with sporadic acute viral hepatitis E from four cities in India. The sequences were compared with prototype sequences for various HEV genotypes and subgenotypes and analyzed using phylogenetic tools to determine the genotype of the isolates. For 12 specimens, a part of HEV ORF2 was also similarly analyzed.
Partial ORF1 sequences of all the 74 isolates belonged to genotype 1 HEV, with 88.2% to 100% nucleotide identity with the prototype genotype 1 isolates. Partial ORF2 sequences for all the 12 isolates also belonged to genotype 1 HEV. On phylogenetic analysis, 71 isolates clustered with prototype genotype 1a HEV; the remaining three isolates were located between subgenotypes 1a and 1c but were closer to the former.
Human sporadic acute hepatitis E in India is caused almost exclusively by genotype 1 HEV.
KeywordsAcute hepatitis Genetic epidemiology Genotype Hepatitis E virus
NG: Acquisition of data, analysis, and interpretation of data, drafting the article, final approval of the version to be submitted
ANS: Analysis and interpretation of data, drafting the article, final approval of the version to be submitted
SD: Acquisition of data, drafting the article, final approval of the version to be submitted
VD: Acquisition of data, drafting the article, final approval of the version to be submitted
KC: Acquisition of data, drafting the article, final approval of the version to be submitted
AG: Acquisition of data, revising the draft critically for important intellectual content, final approval of the version to be submitted
RA: The conception and design of the study, acquisition of data, analysis, and interpretation of data, revising the draft critically for important intellectual content, final approval of the version to be submitted
This work was supported by a research grant from the Indian Council of Medical Research (ICMR), New Delhi. NG and ANS were supported during this work by the Council of Scientific and Industrial Research (CSIR), New Delhi, and ICMR, respectively. The DNA sequencing facility at the authors’ institution is supported by the Department of Science and Technology, Government of India, New Delhi, under its FIST grant program.
Compliance with ethical standards
Conflict of interest
NG, ANS, SD, VKD, KC, AG, and RA declare that they have no conflict of interest.
All procedures performed in the studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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