title: Effects of Astragalus polysaccharide on immune responses of porcine PBMC stimulated with PRRSV or CSFV.
abstract: BACKGROUND
  Astragalus polysaccharide (APS) has been used as an immunomodulator that can enhance immune responses, whereas the immunomodulatory effects of APS on porcine peripheral blood mononuclear cells (PBMCs) exposed to porcine reproductive and respiratory syndrome virus (PRRSV) and classical swine fever virus (CSFV) have not been investigated.
  
  
  RESULTS
  Porcine PBMCs were cultured in complete RPMI media in the presence of the R98-strain of PRRSV (5×10(4) TCID(50)/ml) or C-strain of CSFV (10(3) TCID(50)/ml) with or without APS. The expression of mRNA for CD28, cytotoxic T-lymphocyte antigen 4 (CTLA-4), transforming growth factor-β (TGF-β), interleukin 2 (IL-2) and IL-10 was assayed by TaqMan real-time RT-PCR. The expression of mRNA for CD28 and CTLA-4 increased at 24 h after stimulation of PBMCs with CSFV and the increased production of CTLA-4 was confirmed by western blot analysis, whereas the increases were inhibited by the addition of APS. In addition, APS alone upregulated IL-2 and TGF-β mRNA expression in PBMCs and the addition of APS had the capacity to prevent a further increase in IL-2 mRNA expression in PBMCs during CSFV or PRRSV infection, but had no effect on TGF-β mRNA expression. The production of tumor necrosis factor-alpha (TNF-α) increased at 12 h after stimulation with PRRSV or CSFV, but not with PRRSV plus APS or CSFV plus APS, whereas the addition of APS to PBMCs infected with PRRSV or CSFV promoted IL-10 mRNA expression.
  
  
  CONCLUSIONS
  We suggested that APS had immunomodulatory effects on cells exposed to PRRSV or CSFV. It might be that APS via different mechanisms affects the activities of immune cells during either PRRSV or CSFV infection. This possibility warrants further studies to evaluate whether APS would be an effective adjuvant in vaccines against PRRSV or CSFV.
authors.affiliation: College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Zeng-Yu
authors.initials: ZY
authors.lastname: Zhuge
authors.forename: Yao-Hong
authors.initials: YH
authors.lastname: Zhu
authors.forename: Pan-Qi
authors.initials: PQ
authors.lastname: Liu
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Yan
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yue
authors.forename: Xiao-Gang
authors.initials: XG
authors.lastname: Weng
authors.forename: Rong
authors.initials: R
authors.lastname: Zhang
authors.forename: Jiu-Feng
authors.initials: JF
authors.lastname: Wang
mesh_terms: D000818:Animals; D018106:CD28 Antigens / Q000235:genetics / Q000378:metabolism; D060908:CTLA-4 Antigen / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D006692:Classical Swine Fever Virus / Q000187:drug effects / Q000276:immunology*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation / Q000187:drug effects; D007109:Immunity / Q000187:drug effects*; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D008213:Lymphocyte Activation / Q000187:drug effects; D011134:Polysaccharides / Q000494:pharmacology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000187:drug effects / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D034421:Sus scrofa / Q000276:immunology* / Q000821:virology*
chemical_list: D018106:CD28 Antigens; D060908:CTLA-4 Antigen; D016207:Cytokines; D011134:Polysaccharides; D012333:RNA, Messenger