Study On The Etiopathogenesis Of Piglets Infected With PRRSV And PRRSV/PCV2

An epidemiological investigation was carried out on co-infection of PRRSV (Porcine reproductive and respiratory syndrome virus) and PCV2 (Porcine circovirus type-2) in clinical cases. The results demonstrated that the co-infection rate of PRRSV and PCV2 was as high as 20.2%. Then pathological model was established in ablactation piglets at 40-day-old that inoculated by PRRSV ATCC VR2332 and PRRSV ATCC VR2332 with PCV2 respectively. Primary study showed that PRRSV or PRRSV/PCV2 infection can induce distinctive clinic symptoms. And these viruses can make the piglets become feverish, lose weight significantly, compared with the control. In addition, these viruses can damage immunity and induce immunorepressive on the piglets .All that above was even more serious in piglets infected with PRRSV/PCV2.Dynamic changes of histopathology were studied on some visceral organs such as lung, liver, kidney, cardiac muscle ,brain and immune organs. The results showed that PRRSV chiefly caused interstitial pneumonia, lymphocyte -s and macrophage damaged and induce immunorepressive.All that above was even more serious in piglets infected with PRRSV/PCV2. In addition, the viruses co-infection piglets also manifest extensive lesions of other organizes, especially manifest seriously lymphocytopenia and lymphocyte putrescence of spleen in late time.Apoptosis of cells in lymph,lung,spleen and liver were detected by light microscope, electron microscope and terminal deoxynucleotidyl transferase UIP nick end labeling (TUNEL) on the piglets. The results showed PRRSV and PRRSV/PCV2 could induce incoordinate apoptosis of cells in above organs. And the lymphocyte apoptosis are seriously in spleen, lymph and lung.