The invention provides novel methods and compositions for the vaccination of porcine animals against porcine reproductive and respiratory syndrome virus (PRRSV). Described herein are immunological and/or vaccine compositions comprising a DNA vector encoding a PRRSV protein, particularly a truncated ORF7 protein, which are administered to porcines using needle-free delivery. The plasmid can include more than one nucleic acid molecule such that the plasmid can express more than one antigen. Also disclosed are methods for using and kits employing such compositions.