Establishment of inflammatory model of porcine alveolar macrophages induced by PRRSV

ObjectiveAn inflammatory model of porcine pulmonary alveolar macrophages(PAM)induced by por-cine reproductive and respiratory syndrome virus(PRRSV)was established,and the impact of PRRSV infection on the immune system of piglets were evaluated to provided reference for the clinical diagnosis and prevention of porcine repro-ductive and respiratory syndrome(PRRS).MethodThe 30-day-old healthy weaned piglets were artificially infected with strain PRRSV-GXNN1396 to replicate the PRRS condition.The samples were collected after the piglets were killed.The histopathological changes and distribution of virus in immune organs and tissues were observed by using histopathology and RT-PCR detection technology.Enzyme activity variation such as COX-1 and COX-2 and levels of inflammatory cyto-lines including IL-6,IL-8,IL-10,IL-1β,IFN-γ,MCP-1 and TNF-α in PAM cell were detected.ResultThe results showed that the typical signs of PRRS occurred in infected weaned piglets on the 3rdday after infection of PRRSV-GXNN1396.The viruses were mainly distributed in lungs,lymph nodes,blood and tonsil.The parenchymal cells and re-lated lymphocytes in major organs of challenged piglets showed necrosis and infiltration of inflammatory cells at various degrees.In lung,kidney and spleen especially,macrophages and lymphocytes infiltrated the organs and tissues.The levels of ROS and various factors(COX-2,IL-6,IL-8,IL-10 and TNF-α)in piglets PAM cells all presented a rising trend at early PRRSV infection stage(day 3).Levels of COX-2,IL-6,IL-8 and TNF-α extremely significantly increased (P<0.01).With the increase of infection time,in PAM cell,the levels of factors such as COX-2,IL-6 and IL-8 decreased,yet TNF-α level increased.ConclusionAn inflammatory model of porcine PAM cell induced by PRRSV infection is established,which further testifies that PRRSV mainly affects the immune organs and tissues of piglets to achieve immune suppression.In addition,it is concluded that day 3 of infection is the peak of inflammatory reaction in diseased pigs.