Isolation of a coronavirus from kidney biopsies of endemic Balkan nephropathy patients

Endemic Balkan nephropathy (EBN) is a kidney disease of unknown etiology li mited to Bulgaria, Rumania and former Yugoslavia. Primary kidney tissue cul tures were established as explants from tissue obtained at operations from 5 EBN patients with urinary tract tumors. Four out of the five biopsy speci mens on extended culture incubation at 33 degrees C yielded a coronavirus v irus (EBNV) which was cytopathogenic for human fibroblast and Vero cells. I n cells inoculated with EBNV, cytoplasmic immunofluorescence was found usin g antisera for human coronaviruses OC43 and 229E as well as the porcine tra nsmissible gastroenteric virus and avian (chicken) bronchitis virus. In neu tralization tests, EBNV failed to react with antisera to these viruses. Usi ng hyperimmune serum raised with EBNV, positive cytoplasmic immunofluoresce nce was seen with cells infected with OC43, 229E, TGV and significantly wit h the kidney tissue of the biopsy specimens from the EBN patients. A screen for neutralizing antibody using the EBN virus revealed that 87.2% of EBN p atients on dialysis were positive, also 74% of people from an endemic area were also positive, while only 13.5% from outside were positive. it is sugg ested that a coronavirus is involved in the etiology of the disease and tha t humans are an incidental host of a coronavirus zoonosis.