Mortality Due to Porcine Reproductive and Respiratory Syndrome Virus in Immunocompromised Göttingen Minipigs (Sus scrofa domestica)

Porcine reproductive and respiratory syndrome virus (PRRSV) infection was diagnosed in 6 Göttingen minipigs (Sus scrofa domestica) with severe interstitial pneumonia. The virus was defined as a North American (NA) subtype virus, which is common in the commercial pig population and might be derived from a widely used attenuated live-virus vaccine in Europe. The ORF5 sequence of the isolated PRRSV was 98% identical to the vaccine virus. The affected pigs were part of a lung transplantation model and received tacrolimus and steroids as well as irradiation or CD8 antibody for immunosuppression. The likely source of the infection was pigs that were shedding the identified PRRSV, which were housed in a separate room of the same building. This case report provides evidence that a virus closely related to an attenuated live vaccine might cause severe pneumonia and death in PRRSVseronegative pigs receiving immunosuppressive treatment. We recommend strict barrier housing for immunocompromised pigs.