Abstract: The invention relates to vaccines used in the eradication or control of pestivirus infections, particularly those used in pigs or ruminants. The invention provides nucleic acid, pestivirus-like particles and a pestivirus vaccine, comprising the nucleic acid or particles, which is capable of eliciting a proper immune response without having the ability to spread throughout the vaccinated animal, thereby avoiding the negative consequences of viral spread. Preferably, the immune response allows for serological discrimination between vaccinated animals and wild-type pestivirus infected animals.

Abstract: A method for determining the capability of an arterivirus to replicate in a permissive cell is disclosed. The method includes determining an amino acid at a position that corresponds to an amino acid of a protein of a porcine reproductive and respiratory syndrome virus. The invention also discloses a method for determining the capability of an arterivirus to replicate in a green monkey cell line. The invention further discloses a method for producing arterivirus in a green monkey cell line wherein the virulence of the arterivirus is maintained and the virus yield is increased. Methods for determining the attenuation of an arterivirus and for attenuating the virulence of the arterivirus by changing amino acids are further disclosed.