文本框: STAT1α/βand STAT3α/β SPLICE-FORM ACTIVATION PREDICTS HOST RESPONSE TO VIRAL INFECTION Ning Q1, Luo XP.1, Berger L2, Dennis J 2, Dong YS1., Levy G.A2 1Tongji Hospital, Tongji Medical Colleage, Huazhong University of Science and Technology, Wuhan, China 2 Department of Medicine, University of Toronto, Toronto, Canada Objective: Signal transducer and activator of transcription 1α(STAT1α) is reported to be essential for IFN-γ and IFN-α regulated gene expression, while STAT1β, an alternate splice-form mediates only IFN-αdependent gene expression. STAT3αand STAT3β splice forms are also differentially activated in response to cytokines including IL-6, IL-10 and GMCSF (granulocyte macrophage colony stimulating factor). In this report, we studied the host immune response to viral infection by using a mouse hepatitis model, particularly have examined rates of STAT activation following infection with mouse hepatitis virus (MHV-3), in resistant (Th1 dominated helper T cell response) and sensitive mouse strains (Th2 and acute liver inflammation). Methods: Mice were infected I.P with 100 pfu of MHV-3. The mice were sacrificed at the indicated times and livers and spleens immediately frozen in liquid nitrogen. Nuclear extracts were separated in an 8% SDS-polyacrylamide gel and proteins were detected by immunoblotting. DNA mobility shift assay was also performed to examine the protein-DNA interrection. Rnase protection assay was used to facilitate the mRNA analysis. Results: STAT1 and STAT3 activation in spleen increased 24h to 72h following MHV-3 infections in both sensitive and resistant mouse strains. However, over this time period, ratio of activated αtoβsplice-form for STAT1 and STAT3 increased above 1.0 in resistant A/J mice, while ratio fell to < 0.3 in MHV-3 sensitive Balb/cJ and C3H/HeJ strains. Activated STAT1α/β and STAT3α/β ratio in liver were similar in resistant and sensitive mouse strains. IFN-γ, IL-6, IL-10, and IL-12 cytokine transcript levels in spleen were increased 72 h after infection, but did not distinguish sensitive and resistant mice. Therapy of sensitive Balb/cJ mice with an immunoglobin adjuvant or neutralizing anti-TGF-β antibody elevated STAT1α/β ratio to > 1.0 in spleens, predicting enhanced rates of survival. Conclusion: These results show that ratio of activated STAT1α/β and STAT3α/β in mixed leukocytes from spleen predict outcome to MHV-3 infection, and may be an important marker and therapeutic target for modification of host immune response to other infectious agents. 0679