Innate Antiviral Mechanisms In Mouse Ovary And Early Embryo

Background and objectives:The ovary can be infected by a wide range of virues, which may perturb ovarian functions and female fertility. Some types of viruses, such as hepatis B virus (HBV) and human immune deficiency virus (HIV), may infect eggs and result in maternal-fetal transmission. However, the innate immune responses to viral infection in the ovary, eggs and early stage of embryo genesis remain to be investigated. This thesis focuses on pattern recognition receptor (PRR)-mediated innate antiviral responses in the ovary, eggs and embryogenesis.Materials and Methods:Female mice were used as models in this study. Immunohistochemistry and Western blot were used for the determination of protein distribution and quantification. Gene expression at mRNA level was examined using real-time qRT-PCR. The cytokine production was measured using ELISA. Mouse ovarian granulosa cells, mature eggs, and yolk sac cells were isolated and cultured for in vitro study. The cells were transfected with poly(I:C), mimic viral infection, to induce innate immune responses.Results:PRRs that recognize viral RNA, including toll-like receptor3(TLR3), melanoma differentiation-associated gene5(MDA5), and retinoic acid-inducible gene I (RIG-I) are constitutively expressed in ovarian granulosa and interstitial cells. Poly(I:C) induced innate antiviral responses in the granulosa cells, which are characterized by the upregulation of inflammatory cytokines (such as TNF-a, IL-6, IFN-a and IFN-β) and antiviral proteins, including IFN-stimulated gene15(ISG15),2’-5’-oligoadenylate synthetase (OAS1), and Mx GTPase1(Mxl). Inhibition of individual TLR3, MDA5and RIG-I significantly reduced the innate immune responses. Moreover, the poly(I:C)-induced antiviral responses suppressed estradiol synthesis in granulosa cells. MDA5and RIG-I are also expressed in oocytes and mature eggs, and initiate the innate antiviral responses. At early stage of embryogenesis, TLR3, MDA5, and RIG-I are predominantly expressed in yolk sac cells and initiate innate antiviral responses after poly(I:C) challenge. Activation of NF-κB and interferon regulatory factor3(IRF3) is required for poly (I:C)-induced innate antiviral responses, in all aforementioned cells.Conclusions:Ovarian granulosa cells, oocytes and yolk sac cells are well equipped with innate antiviral system, which would protect ovary, eggs and early embryogenesis from viral infection..