BTNL2 and arthritic joint disease: - 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.