Abstract: The invention relates to the field of PRRS viruses and infectious clones obtained from PRRS viruses. Furthermore, the invention relates to vaccines and diagnostic assays obtainable by using and modifying such infectious clones of PRRS viruses. The invention provides a porcine reproductive and respiratory syndrome virus (PRRSV) replicon having at least some of its original PRRSV nucleic acid deleted, said replicon capable of in vivo RNA replication, said replicon further having been deprived of at least some of its original PRRSV nucleic acid and/or having been supplemented with nucleic acid derived from a heterologous microorganism.

Abstract: The invention relates to the field for Arteriviruses and vaccines directed against infections caused by these viruses. The invention provides an Arteriviruses-like particle comprising at least a first structural protein derived from a first Arterivirus and a second structural protein wherein the second structural protein is at least partly not derived from said first Arterivirus.

Abstract: The invention relates to recombinant Arterivirus replicons. The invention provides the insight that an Arterivirus replicon having at least some of its original arteriviral nucleic acid encoding ORF-7 deleted, as provided herein, can still be capable of in vivo RNA replication, even when further comprising nucleic acid derived from at least one heterologous micro-organism, thereby also providing viable Arteriviruses with deletions proximal to the 3′ end of the genome.

Abstract: The invention relates to the field for Arteriviruses and vaccines directed against infections caused by these viruses. The invention provides an Arteriviruses-like particle comprising at least a first structural protein derived from a first Arterivirus and a second structural protein wherein the second structural protein is at least partly not derived from said first Arterivirus.