To find out which protein members of known microRNA biogenesis pathways are involved in the processing of mature PRRSV-vsRNA1, Drosha, Dicer, Ago2 and RNase L genes were silenced in MARC-145 cells then followed by infection of either of two PRRSV strains (GD-HD, CH-1a) at an MOI of 1. This evidence concerns the gene DICER1 and infection.