If M and GP5 are partially degraded when PLP2’s DUB function is alleviated as in our mutants, virus particles cannot be assembled efficiently, and therefore nsp2TF may be critical to infection, explaining why DUB KO mutants of PRRSV are crippled and restoration of the DUB function is prone to happen in order to rescue particle formation. The gene discussed is PLP2; the disease is infection.