Aptamers, polynucleotides which participate in preventing the Porcine Respiratory and Reproductive Syndrome virus (PRRSV) infection of cells, and nucleic acid molecules, which include a polynucleotide sequence capable of specifically binding the polypeptides domain of the PRRSV that controls infection, constitute the core of the present invention. Also provided are methods of using such nucleic acid molecules, polynucleotides and synthetic antibodies directed against these, for detection, treating and neutralization of PRRSV infection.