COMPARISON OF CYTOKINE PROFILES IN PIGS SINGULARLY OR COINFECTED WITH PCV2, OR MYCOPLASMA HYOPNEUMONIAE

Authors: OPREISSNIG, T - AMES, IOWA; Lunney, Joan; Kuhar, Daniel; THACKER, E - AMES, IOWA; HALBUR, P - AMES, IOWA

Submitted to: International Pig Veterinary Society (IPVS)
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2006
Publication Date: 7/16/2006
Citation: Opreissnig, T., Lunney, J.K., Kuhar, D.J., Thacker, E., Halbur, P.G. 2006. Comparison of cytokine profiles in pigs singularly or coinfected with pcv2, or mycoplasma hyopneumoniae. Pig Veterinary Society International Congress Proceedings. 1:170

Interpretive Summary: Porcine circovirus type 2 (PCV2) is commonly associated with postweaning multisystemic wasting disease (PMWS). In the US, PCV2 is also a major contributor to the porcine respiratory disease complex (PRDC). Previous data demonstrated that M. hyopneumoniae potentiates the severity of PCV2-associated lung and lymphoid lesions and increases the amount and prolongs the presence of PCV2-antigen. The mechanism of this potentiation and the pathogenesis of PCV2-infection in general are still poorly understood. The objectives of this study were to determine immune gene expression profiles in tracheobronchial lymph nodes following experimental infection with PCV2, M. hyopneumoniae, and PCV2/M. hyopneumoniae coinfection and compare the profiles to those of uninfected controls. For this study 4 groups of 7 pigs each were compared; 1) control; 2) inoculated with M. hyopneumoniae intratracheally; 3) inoculated with PCV2 intransally and intramuscularly; and 4) PCV2/M. hyopneumoniae coinfection. All pigs were necropsied at 14 days post PCV2-inoculation (dpi). As expected, M. hyopneumoniae coinfection increased the severity of PCV2-associated lymphoid lesions and amount of PCV2-antigen in TBLN at 14 dpi. Analysis of cytokine gene expression profiles revealed that PCV2 infection was characterized by significantly increased inflammatory cytokine, interferon-gamma (IFN-'), interleukin-8 (IL-8), and chemokine, gene expression. The most significant increase in IFN-' gene expression was observed with the PCV2/M. hyopneumoniae coinfection, in contrast to previous findings of decreased IFN-' mRNA in TBLN of pigs with recent naturally acquired PMWS. The increase in IFN-' and chemokines, and decrease in IFN-', in our study was correlated with increases in severity of microscopic lesions and amount of PCV2-antigen. These analyses of cytokine profiles in experimentally infected pigs should help researchers to better understand the pathogenesis of PCV2-associated diseases.

Technical Abstract: The objectives of this study were to determine immune gene expression profiles in tracheobronchial lymph nodes (TBLN) following experimental infection with Porcine circovirus type 2 (PCV2), Mycoplasma hyopneumoniae, and PCV2/M. hyopneumoniae coinfection and compare the profiles to those of uninfected controls. PCV2 is commonly associated with postweaning multisystemic wasting disease (PMWS). In the US, PCV2 is also a major contributor to the porcine respiratory disease complex (PRDC). Infection with M. hyopneumoniae potentiates the severity of PCV2-associated lung and lymphoid lesions and increases the amount, and prolongs the presence, of PCV2-antigen. The mechanism of this potentiation and the pathogenesis of PCV2-infection in general are still poorly understood. Pigs (6 week old) were randomly divided into 4 groups of 7 pigs; 1) control; 2) inoculated with M. hyopneumoniae intratracheally; 3) inoculated with PCV2 intransally and intramuscularly; and 4) PCV2/M. hyopneumoniae coinfection. All pigs were necropsied at 14 days post PCV2-inoculation (dpi). M. hyopneumoniae coinfection increased the severity of PCV2-associated lymphoid lesions and amount of PCV2-antigen in TBLN at 14 dpi. Analysis of cytokine gene expression profiles revealed that PCV2 infection was characterized by significantly increased interferon-gamma (IFN-'), interleukin-8 (IL-8) and chemokine gene expression. The most significant increase in IFN-' gene expression was observed with the PCV2/M. hyopneumoniae coinfection, in contrast to previous findings of decreased IFN-' mRNA in TBLN of pigs with recent naturally acquired PMWS. The increase in IFN-' and chemokines, and decrease in IFN-', in our study was correlated with increases in severity of microscopic lesions and amount of PCV2-antigen