Immune response in concurrent infection with viral and bacterial infection (PRRS versus Haemophilus parasuis) in respiratory tract of pigs

Porcine reproductive and respiratory syndrome virus (PRRSV) is primary pathogen of pigs causing serious failure in production and reproduction of pigs. We confirm the influence of the infection and the vaccination to the immune response in the experiment in vivo. The immunosuppressive activity of this virus can also predispose to secondary bacterial infections. The animals infected with both pathogens develop more severe clinical signs.

We use the simultaneous infection of porcine alveolar macrophages (PAMs) with PRRSV and Haemophilus parasuis to confirm this fact in in vitro model and describe the differences in comparison to individual infection.

Concurrent infection with PRRSV and H. parasuis increased pro-inflammatory cytokine production (TNF-alfa, IL-1 beta, IL-8) detected both on gene and protein level in comparison to the infection of PRRSV or H. parasuis alone. Simultaneous infection of both pathogens decreased the production of reactive oxygen species (ROS) production although the PRRSV infection alone increased this production. It indicate the inhibitory mechanisms of H. parasuis to the respiratory burst of phagocytes

We confirm the synergic activity of viral (PRRSV) and bacterial (H. parasuis) infection in the pathogenesis and the severity of the respiratory disease of pigs. Severe multifactorial respiratory disease in natural conditions caused by both pathogens could be a consequence of pro-inflammatory mediated immunopathology.

The results were obtained with a financial support of the project LO1218 from the MEYS of the CR under the NPU I program and the project QJ1210120 of the Ministry of Agriculture.

Disclosure of Interest: None Declared.