New Hepatitis E Virus Genotype in Camels, the Middle East - Volume 20, Number 6—June 2014 - Emerging Infectious Disease journal - CDC
Volume 20, Number 6—June 2014
New Hepatitis E Virus Genotype in Camels, the Middle East
Patrick C.Y. Woo1 , Susanna K.P. Lau1, Jade L.L. Teng1, Alan K. L. Tsang1, Marina Joseph, Emily Y.M. Wong, Ying Tang, Saritha Sivakumar, Jun Xie, Ru Bai, Renate Wernery, Ulrich Wernery, and Kwok-Yung Yuen
Author affiliations: State Key Laboratory of Emerging Infectious Diseases, Hong Kong, China (P.C.Y. Woo, S.K.P. Lau, K.-Y. Yuen);The University of Hong Kong, Hong Kong (P.C.Y. Woo, S.K.P. Lau, J.L.L. Teng, A.K.L. Tsang, E.Y.M. Wong, Y. Tang, J. Xie, R. Bai, K.-Y. Yuen); Central Veterinary Research Laboratory, Dubai, United Arab Emirates (M. Joseph, S. Sivakumar, R. Wernery, U. Wernery)
Hepatitis E virus (HEV) belongs to the family Hepeviridae and genus Hepevirus. Among humans worldwide, HEV is the most common cause of acute viral hepatitis. The disease is generally self-limiting, but mortality rates are high among pregnant women and young infants. Chronic HEV infection is a problem for immunocompromised patients, such as those who have received a solid organ transplant and those with HIV infection. In addition to humans, HEV has been found in the other mammals: pigs, boar, deer, rodents, ferrets, rabbits, mongoose, bats, cattle, sheep, foxes, minks, and horses (1–3). Among the 4 known HEV genotypes, HEV1 and HEV2 infect only humans; whereas, HEV3 and HEV4 can infect humans, pigs, and other mammals. Human infections with HEV3 and HEV4 have been associated with consumption of raw or undercooked pork or game meat (4). Traditionally, HEV infection is mainly transmitted through water contaminated with infected feces. Since water supplies and sanitary infrastructures have been improved, animals have become a major source of human HEV infection. We detected HEV in fecal samples from dromedary camels in the Middle East.
As part of a molecular epidemiology study, 203 fecal samples from 203 adult dromedaries (Camelus dromedarius) were submitted to the Central Veterinary Research Laboratory in Dubai, United Arab Emirates, over a 7-month period (January–July 2013). RNA extraction and reverse transcription were performed, as described, to detect other positive-sense single-stranded RNA viruses (5,6). Screening for HEV was performed by PCR amplification of a 284-bp fragment of open reading frame (ORF) 2 in HEV; specific primers used were 5′-TTTATTCTCGTCCAGTCGTTTC-3′ and 5′-GTCAGTGGAGGACCCATATGT-3′, designed from sequence information from our metagenomic study (P.C.Y. Woo et al., unpub. data). PCR was performed according to previously described conditions (7); annealing temperature were set at 50°C. DNA sequencing and quantitative real-time reverse transcription PCR were also performed as described (8). Using strategies we have reported for other positive-sense single-stranded RNA viruses, we performed complete-genome sequencing on 2 HEV-positive samples (5,6). Comparative genomic analysis was performed as described (9). Phylogenetic analysis was conducted in MrBayes5D version 3.1.2 (www.fifthdimension.jp/products/mrbayes5d/) by using an optimal substitution model with 1 million Markov chain Monte Carlo generations; sampling was conducted every 100 generations with a burn-in of 25,000. The substitution model was selected on the basis of the corrected Akaike information criterion by ProtTest version 2.4 (http://darwin.uvigo.es/software/prottest.html).
Reverse transcription PCR for a 284-bp fragment in ORF2 of this HEV, which we named dromedary camel HEV (DcHEV), was positive for 3 fecal samples; viral loads were 3.7 × 105, 4.5 × 105, and 3.2 × 107 copies/mL. Complete-genome sequence data for 2 DcHEV strains (GenBank accession nos. KJ496143–KJ496144) revealed that the genome size was 7,220 bases and had a G+C content of 55% (Table). Overall, the DcHEV genomes differed from all other HEVs by >20% nt (Technical Appendix [PDF - 95 KB - 2 pages] Table).
We thank Wing-Man Ko and Constance Chan, for continuous support. We also thank Shanty Jose and Sweena Liddle for their help with sample preparation.
This work was partly supported by the Hong Kong Special Administrative Region Health and Medical Research Fund; Seed Funding for Theme-Based Research Scheme, and Strategic Research Theme Fund, The University of Hong Kong; Theme-based Research Scheme, Research Grant Council Grant, University Grant Council; and Consultancy Service for Enhancing Laboratory Surveillance of Emerging Infectious Disease for the Hong Kong Special Administrative Region Department of Health.
Dr Woo is professor and head of microbiology at The University of Hong Kong. His research focuses on novel microbe discovery and microbial genomics.
- Figure 1. Predicted genomic organization of hepatitis E virus (HEV) from dromedary camel (DcHEV) and other HEVs, considering the reading frame of open reading frame (ORF) 1 as frame 1.
- Figure 2. Phylogenetic analyses of open reading frame (ORF) 1 (A), ORF2 (B), ORF3 (C), and ORF1/ORF2 proteins, excluding the hypervariable region (HVR) (D) of hepatitis E virus (HEV) from dromedary...
- Technical Appendix. Comparison of nucleotide and deduced amino acid sequence identities of hepatitis E virus (HEV) from dromedary camels (DcHEV) and other genotypes of HEV; alignment of nucleotide sequences showing potential... 95 KB
Suggested citation for this article: Woo PCY, Lau SKP, Teng JLL, Tsang AKL, Joseph M, Wong EYM, et al. New hepatitis E virus genotype in camels, the Middle East. Emerg Infect Dis [Internet]. 2014 Jun [date cited]. http://dx.doi.org/10.3201/eid2006.140140
1These authors contributed equally to this article.