WIDE EXPOSURE OF ADULT PIGS TO HEPATITIS E VIRUS BUT LACK OF EVIDENCE OF ACTIVE INFECTION IN PIGS AT SLAUGHTERHOUSE

Hepatitis E virus is definitively considered an emerging treat in Europe for the increased number of humans cases reported and for the wide presence of the virus in pigs at farms. Most of human cases in industrialized countries are caused by the zoonotic HEV-3 genotype that is largely detected in both domestic and wild pigs. The main route of transmission in EU of the HEV-3 is foodborne, trough consumption of raw or undercooked pork and wild boar containing liver. Pigs still positive for HEV have been detected at the slaughterhouse in feces, bile and liver samples. The liver is the main organ of HEV replication, resulting frequently positive, but the probability of HEV liver positive decreases with the age of animals. At slaughterhouse, viremia has been rarely investigated and only sporadically detected. Aim: The present study aimed to investigate the prevalence of HEV positive batches of pigs being slaughtered evaluating the presence of animals still shedding HEV in feces shortly before being slaughtered. The detection of anti-HEV IgM antibodies and anti-HEV total antibodies was also evaluated as evidence of both recent and past infection. Methods: 255 fecal pools picked randomly from the floor of the transport trucks were analysed by Real-Time PCR to detect the presence of HEV RNA. The seroprevalence was determined for 260 serum samples using a commercial ELISA kit (HEV ELISA 4.0 kits, MP Biomedicals), specific for the detection of total antibodies in animal sera. For the detection of HEV-IgM antibodies in sera positives in the first ELISA test, a commercial ELISA kit (HEV ELISA 3.0 kits, MP Biomedicals) was used with some modifications. Afterward, presence of viremic animals was also assessed, performing a Real-Time PCR analysis on 80 serum samples including all those resulted positive for anti-HEV IgM antibodies. Results: A high seroprevalence was observed in the 260 analysed sera, 232 samples (89.23%) resulted positives for anti-HEV total antibodies. Data obtained showed the absence of viremic pigs, even among animals positive for anti-HEV IgM (28/260 10.77%). No fecal shedding of HEV in pigs was detected. Conclusion: Seroprevalence results confirmed a wide exposure of the animals to HEV, as revealed by the high number of anti-HEV seropositive pigs in the 6 batches investigated. This work was supported by the Italian Ministry of Health, grant: RF-2016-02361926.