- PCV2 and Ss2 coinfection induced more severe pneumonia, myocarditis, and arthritis, worsened the inflammatory response, and reduced the macrophage antigen presentation. - The severity of the PCV2-associated lung and lymphoid lesions, the amount of the PCV2 antigen, and the incidence of PMWS in pigs were worsen in the presence of Mhp. This evidence concerns the gene BTNL2 and pneumonia.