Direct TLR2 signaling is critical for NK cell activation and function in response to vaccinia viral infection.

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Natural killer (NK) cells play an essential role in innate immune control of poxviral infections in vivo. However, the mechanism(s) underlying NK cell activation and function in response to poxviruses remains poorly understood. In a mouse model of infection with vaccinia virus (VV), the most studied member of the poxvirus family, we identified that the Toll-like receptor (TLR) 2-myeloid differentiating factor 88 (MyD88) pathway was critical for the activation of NK cells and the control of VV infection in vivo. We further showed that TLR2 signaling on NK cells, but not on accessory cells such as dendritic cells (DCs), was necessary for NK cell activation and that this intrinsic TLR2-MyD88 signaling pathway was required for NK cell activation and played a critical role in the control of VV infection in vivo. In addition, we showed that the activating receptor NKG2D was also important for efficient NK activation and function, as well as recognition of VV-infected targets. We further demonstrated that VV could directly activate NK cells via TLR2 in the presence of cytokines in vitro and TLR2-MyD88-dependent activation of NK cells by VV was mediated through the phosphatidylinositol 3-kinase (PI3K)-extracellular signal-regulated kinase (ERK) pathway. Taken together, these results represent the first evidence that intrinsic TLR signaling is critical for NK cell activation and function in the control of a viral infection in vivo, indicate that multiple pathways are required for efficient NK cell activation and function in response to VV infection, and may provide important insights into the design of effective strategies to combat poxviral infections.





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Martinez, Jennifer, Xiaopei Huang and Yiping Yang (2010). Direct TLR2 signaling is critical for NK cell activation and function in response to vaccinia viral infection. PLoS Pathog, 6(3). p. e1000811. 10.1371/journal.ppat.1000811 Retrieved from

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Xiaopei Huang

Assistant Professor in Medicine

Yiping Yang

Professor of Medicine

The goal of Dr. Yang’s laboratory is to understand the molecular and cellular mechanisms leading to the generation of potent and long-lasting anti-tumor immunity, and to develop effective gene immunotherapeutic strategies for treating cancer. Furthermore, rational pre-clinical approaches will be tested in clinical trials in patients with Epstein-Barr virus (EBV)-related malignancies. Specifically, we focus on the following areas:

1. Innate Immunity to Viruses. Recombinant vaccinia virus and adenovirus have been developed as potent vaccine vehicles for treating cancer and infectious diseases. Recent studies have shown that the unique potency of these viruses lies in their effective activation of the innate immune system. How these viruses activate the innate immune system remains largely unknown. We have been interested in the role of pattern-recognition receptors including Toll-like receptors (TLRs)in innate immune recognition of these viruses as well as their signaling pathways. In addition, we are investigating the role of innate immune cells such as natural killer (NK) cells in innate and adaptive immune responses to these viruses. A full understanding of these processes will help us design effective vaccine strategies.

2. T Cell Memory. Eliciting long-lived memory T cell response is an ultimate goal of vaccination to provide long-term immunity against cancer. However, it is not clear what controls the formation of long-lived memory T cells. The understanding of mechanisms underlying memory T cell formation will provide important insights into the design of effective vaccines for treating cancer.

3. Regulatory T Cell Biology. Accumulating evidence has shown that the immunosuppressive CD4+CD25+Foxp3+ regulatory T cells (TReg) play a critical role in the suppression of anti-tumor immunity. However, little is known about how TReg suppress T cell activation in vivo. Delineation of mechanisms underlying TReg-mediated suppression in vivo will help develop strategies to overcome TReg-mediated suppression in favor of boosting anti-tumor immunity.

4. Immunotherapy for EBV-associated Malignancies. Clinically, EBV-associated malignancies such as Hodgkin’s lymphoma offer a unique model to explore antigen-defined immunotherapy approaches because EBV-derived tumor antigens are specific for tumor cells only. Using this clinical model, we will test the utility of rational strategies identified in our preclinical models.

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