Fatal disease associated with Swine Hepatitis E virus and Porcine circovirus 2 co-infection in four weaned pigs in China

Background: In recent decades, Porcine circovirus 2 (PCV2) infection has been recognized as the causative agent of postweaning multisystemic wasting syndrome, and has become a threat to the swine industry. Hepatitis E virus (HEV) is another high prevalent pathogen in swine in many regions of the world. PCV2 and HEV are both highly prevalent in pig farms in China. Case presentation: In this study, we characterized the HEV and PCV2 co-infection in 2-3 month-old piglets, based on pathogen identification and the pathological changes observed, in Hebei Province, China. The pathological changes were severe, and general hyperemia, hemorrhage, inflammatory cell infiltration, and necrosis were evident in the tissues of dead swine. PCR was used to identify the pathogen and we tested for eight viruses (HEV, Porcine reproductive and respiratory syndrome virus, PCV2, Classical swine fever virus, Porcine epidemic diarrhea virus, Transmissible gastroenteritis coronavirus, Porcine parvovirus and Pseudorabies virus) that are prevalent in Chinese pig farms. The livers, kidneys, spleens, and other organs of the necropsied swine were positive for HEV and/or PCV2. Immunohistochemical staining showed HEV-and PCV2-antigen-positive signals in the livers, kidneys, lungs, lymph nodes, and intestine. Conclusion: HEV and PCV2 co-infection in piglets was detected in four out of seven dead pigs from two pig farms in Hebei, China, producing severe pathological changes. The natural co-infection of HEV and PCV2 in pigs in China has rarely been reported. We speculate that co-infection with PCV2 and HEV may bring some negative effect on pig production and recommend that more attention should be paid to this phenomenon.