Abstract
BackgroundHepatitis E virus (HEV) has been reported in the human population and pigs are a recognized reservoir for HEV and a possible source of HEV transmission to humans. Spray-dried porcine plasma (SDPP) is an ingredient commonly used in feed for pigs around the world. Even though processing conditions used to produce SDPP should be adequate to inactivate HEV, it was of interest to analyze commercial SDPP samples for presence of genome and antibodies (AB) against HEV and to retrospectively analyze serum samples collected from pigs used in past experiments that had been fed diets containing either 0% or 8% SDPP to detect potential transmission of HEV as determined by seroconversion.ResultsEighty-five commercial SDPP samples were analyzed by ELISA and 100% of them contained AB against HEV, while 22.4% (11 of 49 samples analyzed) were positive for HEV RNA.Frozen sera samples (n = 140) collected from 70 pigs used in past experiments that had been fed diets containing either 0% or 8% commercial SDPP was analyzed by ELISA for AB against HEV. Age of pigs at sera sampling ranged from 3 to 15 weeks and feeding duration of diets ranged from approximately 4 to 9 weeks. One lot of SDPP used in one experiment was analyzed and confirmed to contain HEV RNA. Regardless of the diet fed, some sera samples collected at the beginning of an experiment contained AB titer against HEV. These sera samples were collected from weaned pigs prior to feeding of the experimental diets and the HEV titer was probably from maternal origin. However, by the end of the experiments, HEV titer was not detected or had declined by more than 50% of the initial titer concentration.ConclusionsTo our knowledge, this is the first study reporting presence of HEV AB titer and RNA in SDPP. Retrospective analysis of serum collected from pigs fed diets with SDPP revealed no indication of seroconversion to HEV. The results indicate that feeding SDPP in diets for pigs does not represent a risk of transmitting HEV, even though HEV genome may be detected in SDPP.
Highlights
Hepatitis E virus (HEV) has been reported in the human population and pigs are a recognized reservoir for HEV and a possible source of HEV transmission to humans
The objectives of the study were to analyze the presence of HEV RNA and antibodies (AB) in commercial samples of Spray-dried porcine plasma (SDPP) obtained from a Spanish manufacturer and to retrospectively analyze serum samples collected from pigs used in past studies that were fed diets containing 8% SDPP to determine any potential risk of transmission of HEV as indicated by seroconversion in those animals
Retrospective HEV titer analysis of sera samples collected from pigs fed diets containing SDPP Serum samples (n = 72) from 36 pigs used in an experiment in which pigs were fed diets containing either 0% SDPP (n = 18) or 8% SDPP (n = 18) for 9 weeks was retrospectively analyzed for HEV AB by enzyme linked inmuno-assay (ELISA)
Summary
Hepatitis E virus (HEV) has been reported in the human population and pigs are a recognized reservoir for HEV and a possible source of HEV transmission to humans. Spray-dried porcine plasma (SDPP) is an ingredient commonly used in feed for pigs around the world. Spray-dried porcine plasma (SDPP) as an ingredient in diets for nursery pigs is well recognized to improve growth rate, feed intake, feed efficiency, and to reduce post-weaning diarrhea, mortality, and morbidity [1,2]. Pigs are recognized as a potential reservoir for HEV [5,6] and as a possible source of HEV transmission to humans [7,8,9]. The virus has been identified on swine farms in many geographical areas, including the USA and Europe, and the reported prevalence ranges from 22% to 55% [10,11]
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