Observational Study
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World J Gastroenterol. Jun 28, 2014; 20(24): 7955-7963
Published online Jun 28, 2014. doi: 10.3748/wjg.v20.i24.7955
Seroprevalence and evolutionary dynamics of genotype 4 hepatitis E virus in Shandong Province, China
Dong Yang, Mei Jiang, Min Jin, Zhi-Gang Qiu, Zhi-Qiang Shen, Wei-Hong Cui, Da-Ning Wang, Lian-Feng Gong, Bo Li, Xin-Wei Wang, Jun-Wen Li
Dong Yang, Min Jin, Zhi-Gang Qiu, Zhi-Qiang Shen, Da-Ning Wang, Xin-Wei Wang, Jun-Wen Li, Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Tianjin 300050, China
Dong Yang, Min Jin, Zhi-Gang Qiu, Zhi-Qiang Shen, Da-Ning Wang, Xin-Wei Wang, Jun-Wen Li, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China
Mei Jiang, Wei-Hong Cui, Lian-Feng Gong, Bo Li, Yantai Center for Disease Control and Prevention, Yantai 264003, Shandong Province, China
Author contributions: Yang D and Jiang M contributed equally to this work; Li JW, Jin M and Yang D designed the research and wrote the manuscript; Jiang M, Qiu ZG, Shen ZQ and Cui WH performed the research; Li B, Gong LF, Wang DN and Wang XW analyzed the data.
Supported by National Natural Science Foundation of China, No. 30930078
Correspondence to: Jun-Wen Li, MD, PhD, Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, No.1, Dali Road, Tianjin 300050, China. junwen9999@hotmail.com
Telephone: +86-22-84655345 Fax: +86-22-23328809
Received: January 16, 2014
Revised: March 25, 2014
Accepted: April 8, 2014
Published online: June 28, 2014
Abstract

AIM: To investigate the seroprevalence and evolutionary dynamics of hepatitis E virus (HEV) and assess the ancestor of HEVs in China’s Shandong Province.

METHODS: A total of 2028 serum, 60 fecal and 82 bile samples were collected from the general human population, patients and swine, respectively. This seroepidemiological study was conducted using an immunnosorbent assay and HEV RNA was detected by the reverse transcription-nested polymerase chain reaction (RT-nPCR) method. Complete genome sequences of the prevalent strains (CH-YT-HEV01, CH-YT-HEV02 and CH-YT-sHEV01) were determined, and the sequences were analyzed phylogenetically. In addition, the evolutionary dynamics of three HEV isolates were determined using the framework of coalescent analysis in the program package BEAST, and the time of the most recent common ancestors (TMRCAs) of China-indigenous genotype 4 HEV isolates was calculated.

RESULTS: The overall viral burden in the general human population was 0.1%, and the positive rates of anti-HEV IgG and IgM in the serum specimens were 25.1% (509/2028) and 2.3% (51/2028), respectively. In addition, IgG positivity increased with age. The phylogenetic analysis based on the full-length nucleotide sequences showed that the strain CH-YT-HEV02 was directly related to CH-YT-sHEV01 with a 94% identity, suggesting that they were involved in cross-species transmission. The isolate CH-YT-HEV01 was close to HB-3 and CHN-SD-sHEV with a bootstrap value of 100%, sharing a 96.1%-96.4% identity with each other. Surprisingly, the HB-3 strain was a representative strain prevalent in swine in Hubei, and the isolate CHN-SD-sHEV was obtained from swine in Shandong in a previous report. TMRCA for the clade of CH-YT-HEV01 and HB-3 was 2003, which was consistent with the TMRCA for the clade of CHN-SD-sHEV and HB-3, and they were both earlier than the TMRCA for the clade of CH-YT-HEV01 and CHN-SD-sHEV (2004).

CONCLUSION: The strains CH-YT-HEV01, CHN-SD-sHEV and HB-3 are involved in trans-regional transmission, and the ancestors of HEVs in Shandong come from Hubei Province.

Keywords: Hepatitis E virus, Zoonotic, Cross-species transmission, Trans-regional transmission, Evolutionary dynamics

Core tip: This is the first study to investigate the genetic history of hepatitis E virus (HEV) based on the complete genome sequences in China. The results suggested that the strains CH-YT-HEV02 and CH-YT-sHEV01 were involved in cross-species transmission between swine and humans in Shandong Province. The strains CH-YT-HEV01, CHN-SD-sHEV and HB-3 were involved in trans-regional transmission between Hebei and Shandong, and the coalescent analysis suggested that the ancestors of HEVs in Shandong come from Hubei Province.