The present invention relates to nucleic acids comprising:(a) a sequence encoding a polypeptide comprising the amino acid sequence of SEQ ID NO:1 (sequence of the GP5 ecto-domain of the European strain of PRRSV) or a sequence having at least 85% identity to SEQ ID NO:1, which sequence includes at least one amino acid capable of forming a disulfide bridge and(b) a sequence encoding a polypeptide comprising the amino acid sequence SEQ ID NO:2 (sequence of the GP5 M protein of the European strain of PRRSV) or a sequence having at least 85% identity to SEQ ID NO: 2(c) wherein the nucleic acid does not comprise a sequence encoding a polypeptide comprising the amino acid sequence of SEQ ID NO:3 (sequence of the GP5 protein except the ecto-domain of the European strain of PRRSV) or a sequence having at least 80% identity to SEQ ID NO:3.The present invention further provides respective nucleic acids from other strains of PRRSV and their use as a vaccine for the treatment of animals.
