Abstract
Pigs are considered the main reservoir of genotypes 3 and 4 of the human pathogen hepatitis E virus (HEV). These viruses are prevalent at a high level in swine herds globally, meaning that consumers may be exposed to HEV from the food chain if the virus is present in pigs at slaughter. The aim of this study was to determine the HEV infection dynamics from birth to slaughter using 104 pigs from 11 sows in a single production system. Serum was collected from sows at 2 weeks prior to farrowing, in addition feces and serum samples were collected from the pigs every second week, from week 1 to week 17. Feces and selected organs were also sampled from 10 pigs following slaughter at week 20. All the samples were tested for HEV RNA by real-time RT-PCR and the serum samples were tested for HEV-specific antibodies using a commercial ELISA. Maternal antibodies (MAbs) were only present in pigs from sows with high levels of antibodies and all pigs, except one, seroconverted to HEV during weeks 13–17. In total, 65.5% of the pigs tested positive for HEV RNA at least once during the study (during weeks 13, 15, and/or 17) and significantly fewer pigs with a high level of MAbs became shedders. In contrast, the level of MAbs had no impact on the time of onset and duration of virus shedding. HEV was detected in feces and organs, but not in muscle, in 3 out of 10 pigs at slaughter, indicating that detection of HEV in feces is indicative of an HEV positivity in organs. In conclusion, a high proportion of pigs in a HEV positive herd were infected and shed virus during the finisher stage and some of the pigs also contained HEV RNA in feces and organs at slaughter. The presence of MAbs reduced the prevalence of HEV shedding animals, therefore, sow vaccination may be an option to decrease the prevalence of HEV positive animals at slaughter.
Highlights
Hepatitis E virus (HEV) can cause severe infections in humans
The pigs in groups 1 and 2 showed similar anti-hepatitis E virus (HEV) Ab profiles in serum with OD values below the cut off until seroconversion that occurred between weeks 11 and 13 followed by a steady further increase in HEV IgG levels which lasted until the end of the observation period at week 17 (Figure 1)
To investigate the efficacy of passive transfer of maternal antibodies on the HEV infection dynamic in the offspring, the 104 piglets were allocated to one of three groups based on the level of anti-HEV antibodies measured in the sows 2 weeks prior to farrowing
Summary
Hepatitis E virus (HEV) can cause severe infections in humans. Four genotypes of HEV are known; genotypes 1 and 2 are exclusively found in humans whereas genotypes 3 and 4 have been found in humans and pigs. In several European countries, there has been a dramatic increase in human cases of HEV infection caused by Genotype 3 strains. These viruses have a high sequence identity to contemporary strains circulating in pigs, indicating that swineto-human transmission of HEV is a common event [2]. High prevalence of antiHEV antibodies (Abs) in swine herds has been reported from several countries. Detection of the high HEV seroprevalence in older samples indicated that HEV has been present in pigs for decades. A number of studies have shown that consumers are exposed to Dynamics of HEV in Pigs
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