Our research coincides with increasing interest in the newly emerging zoonosis, the hepatitis E virus, and provides new information regarding infection distribution in Slovenian pig herds. Since HEV is a zoonosis, our goal was to investigate the existing condition in Slovenian slaughterhouses and to assess associated health risks posed to consumers and personnel. Sampling of pigs was conducted in four Slovenian slaughterhouses, between June and September 2014. Feces, liver and bile samples were collected from 811 healthy pigs (different age categories). At the time of slaughter, swab samples of different surfaces and samples of minced meat and sausages were also taken. All samples were analyzed with real time PCR (RT-PCR) for the presence of HEV. Blood samples taken from the same pigs were analyzed for the presence of IgG HEV antibodies. The highest number of HEV positive animals was found in the 3 month old age group of pigs (322 animals), where 17% of animals were HEV positive. In the age group of 6 month old pigs (400 animals), only one liver sample and one bile sample was positive, which was significantly less than we would have expected. Out of 89 pigs that were older than 1 year, none was HEV positive. Out of 63 surface swabs, two were positive for the presence of HEV. None of the minced meat and sausage samples was positive. A phylogenetic tree, generated combining sequences obtained from Slovenian strains (45 positive samples) and nucleotide sequences of HEV strains derived from GeneBank, revealed high genetic variability between samples, allowing classification of the identified Slovenian strains into four different subtypes of genotype 3 (3a, 3b, 3e and 3f). Genotype 4 was not found. Additionally, five HEV positive human samples were sequenced, although sequencing was unsuccessful due to an insufficient amount of viral RNA. With two commercial ELISA (ID Screen® Hepatitis E Indirect Multi-species (IDvet) and HEV-IgG ELISA porcine (Axiom)) we analyzed blood samples from domestic pigs for the presence of IgG HEV antibodies. We analyzed 351 randomly selected serum samples collected from pigs located in different parts of Slovenia (these samples were collected within the scope of annual monitoring of infectious diseases in 2013 and 2014) and 359 samples collected from pigs at slaughter in 2014. Comparison of results from both ELISA showed that Axiom ELISA is more suitable as a screening method. A human immunoblot test was optimized and standardized to test 38 serum samples that showed discrepancies in results obtained with Axion and IDvet ELISA kits. The work presented herein represents the first systematic, wide scope analysis on the presence of HEV in pigs at slaughter in Slovenia. Results of the research have contributed to a better understanding of pig HEV infection status at slaughter and have shown a more detailed picture of seroprevalence status in pig farming. Since our research included a great number of samples and dispersion of different farms around the country, we can safely say that the obtained results show accurate information about pig HEV infections in Slovenia.
|
