Recombinant PRRS viruses expressing several indicator proteins have replication and infection dynamics similar to the parental strain in both MARC-145 and porcine cells. Therefore, they may be used to decipher the role of host factors in PRRSV infection [38, 39] . Using several indicator protein-expressing viruses, in particular the Rluc-expressing PRRSV, we showed that TSG101 was significantly involved in PRRSV infection at the early phase of the infection.