Identification of a bisegmented double-stranded RNA virus (picobirnavirus) in calf faeces

To determine the incidence of rotavirus infection among dairy herds in the State of São Paulo, Brazil, 576 faecal samples obtained from calves aged 1–45 days with and without diarrhoea, reared on 63 dairy cattle farms, were analyzed. Polyacrylamide gel electrophoresis (PAGE) identified 28 samples positive for group A rotavirus, while four samples, two diarrhoeic and two non-diarrhoeic, showed a bisegmented genome with a typical picobirnavirus pattern. Electron microscopy revealed spherical virus particles with a diameter of 37 nm and without a defined surface structure. The present study is the first report of a bisegmented virus identified in cattle in Brazil.