title: Reduced prevalence of genotype 3 HEV in Shanghai pig farms and hypothetical homeostasis of porcine HEV reservoir.
abstract: A total of 493 fecal samples collected from local Shanghai pig farms were examined for Hepatitis E virus (HEV) after the introduction of stricter sanitary measures following outbreaks of a high fever-associated pig disease during 2006 and 2007. Our investigation revealed that, while the overall occurrence of HEV RNA positives decreased by only 3.7%, the incidence of HEV genotype 4 increased from 9.8% to 20.6% whereas the incidence of HEV genotype 3 decreased from 16.2% to 1.6%. As well as demonstrating that HEV genotype 3 was more sensitive than genotype 4 to the stricter sanitation procedures, our data also suggested that a homeostasis mechanism, whereby the overall incidence of HEV is maintained at a specific population level, might exist in the porcine HEV reservoir. Furthermore, in one case, we encountered the coexistence of HEV genotypes 3 and 4 within the same sample, indicating the possibility of future HEV infections of increased severity and even the occurrence of a HEV pandemic due to genetic recombination and species evolution.
authors.affiliation: Institute of Animal Science and Veterinary Medicine, Shanghai Academy of Agricultural Sciences, 2901 Beidi Road, Shanghai 201106, China. zhenli60@sh163.net
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.forename: Shuisheng
authors.initials: S
authors.lastname: Yu
authors.forename: Shijuan
authors.initials: S
authors.lastname: Dong
authors.forename: Yumin
authors.initials: Y
authors.lastname: Zhu
authors.forename: Fusheng
authors.initials: F
authors.lastname: Si
authors.forename: Shiyuan
authors.initials: S
authors.lastname: Shen
authors.forename: Zhongqi
authors.initials: Z
authors.lastname: Jiang
authors.forename: Ruisong
authors.initials: R
authors.lastname: Yu
authors.forename: Sixiang
authors.initials: S
authors.lastname: Zou
mesh_terms: D000383:Agriculture; D000818:Animals; D002681:China / Q000453:epidemiology; D005243:Feces / Q000821:virology; D014644:Genetic Variation; D005838:Genotype; D016751:Hepatitis E / Q000662:veterinary / Q000821:virology; D016752:Hepatitis E virus / Q000235:genetics*; D010802:Phylogeny; D015995:Prevalence; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000821:virology*