The present invention relates to chimeric pestiviruses having utility as immunogenic compositions and vaccines wherein said chimeric pestivirus comprises a bovine viral diarrhea virus which does not express its homologous Ems protein, further wherein said chimeric pestivirus expresses a heterologous Ems protein derived from another pestivirus, or a natural, synthetic or genetic variant of said heterologous Erns protein. Also described herein are methods and kits for treating or preventing the spread of bovine viral diarrhea virus infection, as well as methods and kits for differentiating between vaccinated and wild-type infected animals.
