Conversely, evaluation of serum samples from our previous animal experiment suggested these is no existence of pGM-CSF in serum sample obtained from PRRSV-JXA1-infected piglets whereas upregulated pGM-CSF was only observed in sera of PRRSV-JXA1-infected piglets after the received therapeutic mAb treatment against PRRSV infection and increased pGM-CSF levels in serum aligned with reduced pneumonia incidence in mAb-treated animals. This evidence concerns the gene CSF1 and pneumonia.