Genetic characterization of hepatitis E virus from wild boar in China

Abstract

Hepatitis E virus (HEV), the causative agent of hepatitis E (HE), is classified into four major genotypes (1–4), with wild boar being the main natural reservoir for genotypes 3 and 4. However, little is known about the prevalence of HEV infection in wild boars in China. In this study, RT‐nested PCR and RT‐quantitative PCR were used to detect the HEV RNA in tissue samples taken from 331 free‐ranging wild boars collected between 2018 and 2020 from 24 regions across China, and the partial ORF2 genes or complete genomes of the positive samples were sequenced. Furthermore, antibodies against HEV in 216 serum samples from wild boars were tested by ELISA. As a result, HEV RNA was detected in nine out of 331 liver samples of wild boars (2.72%), which were distributed in eight regions. Genetic and evolutionary analysis of partial ORF2 sequences indicated that the HEV strains identified in this study share 83.9%–100% nucleotide sequence identity and belong to subtypes 4d (n = 6), 4g (n = 2), and 4h (n = 1), and similar phylogeny was obtained using the complete genome sequences of seven wild boar HEV strains. Additionally, the HEV viral loads were higher in the liver than in other tissues and blood. Moreover, 61 out of 216 sera (28.2%) from wild boars tested positive for anti‐HEV antibodies. To our knowledge, this is the first study to report the epidemiological situations of HEV infections in free‐ranging wild boars in China, and the obtained data are valuable for prevention and control of HE.

Prevalence of Hepatitis E Virus (HEV) in Feral and Farmed Wild Boars in Xinjiang, Northwest China

“…A previous study [ 30 ] reported 2.7% (9/331) HEV RNA positivity from liver samples of wild boars in 25 provinces of China and 8.3% (1/12) in Xinjiang, consistent with our results (7.9%, 7/89). In our study, the HEV RNA positivity rate from liver samples was more than 10-fold higher than that in fecal samples ( Table S1 ), probably due to its hepatotropic characteristics that HEV RNA concentration in liver and bile were 10-fold higher than that in fecal and other samples [ 49 ].…”

“…Wild boars can be infected with genotypes HEV-3–HEV-6 in other countries [ 45 ], and our study first identified sub-genotype HEV-4a from wild boars in China. Together with Gong et al [ 30 ], our results indicated that only HEV-4 (e.g., HEV-4a, HEV-4d, HEV-4g, and HEV-4h) circulated among wild boars in China. The high seroprevalence suggested that feral and farmed wild boars are zoonotic HEV reservoirs.…”

“…A previous study showed that antibodies to HEV were detected in 24.5% of the farmed wild boars [ 29 ]. Another study showed that 28.2% of the wild boars were seropositive, among which HEV-4d, HEV-4g, and HEV-4h were identified [ 30 ]. Circulation of HEV in wild boars poses a zoonotic risk, and severe HEV infections after consumption of uncooked wild boar livers have been reported [ 31 ].…”

Epizootiological surveillance of porcine circoviruses in free-ranging wild boars in China

“…In addition to domestic pigs, PCVs have also been found to be prevalent in free-ranging wild boars in many foreign countries, including Italy ( Amoroso et al., 2021 ; Dei Giudici et al., 2020 ), Korea ( Song et al., 2020 ), Brazil ( Souza et al., 2021 ), Austria ( Auer et al., 2022 ), Ukraine ( Rudova et al., 2022 ), Hungary ( Cságola et al., 2006 ), Portugal ( de Sousa Moreira et al., 2022 ) and Germany ( Prinz et al., 2019 ), while the epizootiology of PCVs in Chinese free-ranging wild boars remains little research because of the difficulty of sample collection, although PCV2 infection was observed in hybrid wild boars from north-east China and PCVs in wild boar from Jiangxi Province of China ( Guo et al., 2019 ; Wu et al., 2022 ). Since wild boars are considered an important reservoir of animal and zoonotic pathogens, it is important to identify the epizootiology trends of important and emerging infectious diseases in wild boars for both livestock production and public health issues ( Meng et al., 2009 ; Li et al., 2019 ; Gong et al., 2022 ). In this study, the genetic characteristics and serological prevalence of PCVs in Chinese free-ranging wild boars were investigated.…”