Plasmacytoid dendritic cells (pDCs) are critical innate immune cell that provide high levels of type I interferons (IFNs) in response to a variety of viruses. Type I IFN system plays a vital role in the early innate immune responses during virus infection. Until recently, the mechanism by which pDCs recognize viruses and elicit type I IFN secretion was not known. One of the major pathways of pathogen detection involves the recognition of evolutionary conserved patterns found on microbes via pattern recognition receptors. The Toll-like receptor (TLR) family of proteins are crucial in the activation of DCs and the generation of adaptive immunity following bacterial, parasitic and fungal infections. Yet, much less is known with regards to the role of TLRs in anti-viral immunity. In recent studies, we provided both in vitro and in vivo evidence for the requirement of TLR9 and TLR7 in type I IFN secretion from pDCs in response to a variety of viruses. Double stranded (ds) DNA viruses, herpes simplex viruses (HSV), are detected by TLR9 whereas single stranded (ss) RNA viruses, influenza and vesicular stomatitis virus (VSV), are recognized through TLR7. Further, recognition of both types of viruses through TLR7 and TLR9 required acidification of the endosomes. However, major gaps in our understanding of the pDCs exist in the following areas;(1) molecular mechanism of IFN induction upon viral infection and/or uptake, (2) cellular mechanism by which viruses are internalized into the lysosomal compartment, and (3) the role of pDCs in the context of in vivo innate and adaptive immunity to viruses. Thus, in this proposal, we describe systematic approaches to address these fundamental questions. Specifically, in Aim 1, we propose to identify the molecular mechanisms involved in the induction of type I IFN production upon recognition of live viruses in pDCs. Experiments proposed in Aim 2 will critically examine the endocytic pathways utilized by pDCs to internalize virions. Finally, in Aim 3, we propose to evaluate the in vivo role of pDCs in innate and adaptive immune responses to mucosal viral infections with influenza and HSV-2. Through basic understanding of the biology of pDCs, these studies will help to provide important foundation with which to design immunological interventions against viral diseases.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-IHD (01))
Program Officer
Gondre-Lewis, Timothy A
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Yale University
Public Health & Prev Medicine
Schools of Medicine
New Haven
United States
Zip Code
Iijima, Norifumi; Iwasaki, Akiko (2016) Access of protective antiviral antibody to neuronal tissues requires CD4 T-cell help. Nature 533:552-6
Khoury-Hanold, William; Iwasaki, Akiko (2016) Autophagy Snuffs a Macrophage's Inner Fire. Cell Host Microbe 19:9-11
Gopinath, Smita; Kumamoto, Yosuke; Iwasaki, Akiko (2016) O-linked sugars sound the alarm. Nat Immunol 17:119-20
Pillai, Padmini S; Molony, Ryan D; Martinod, Kimberly et al. (2016) Mx1 reveals innate pathways to antiviral resistance and lethal influenza disease. Science 352:463-6
Foxman, Ellen F; Storer, James A; Vanaja, Kiran et al. (2016) Two interferon-independent double-stranded RNA-induced host defense strategies suppress the common cold virus at warm temperature. Proc Natl Acad Sci U S A 113:8496-501
Shin, Haina; Kumamoto, Yosuke; Gopinath, Smita et al. (2016) CD301b+ dendritic cells stimulate tissue-resident memory CD8+ T cells to protect against genital HSV-2. Nat Commun 7:13346
Iwasaki, Akiko; Medzhitov, Ruslan (2015) Control of adaptive immunity by the innate immune system. Nat Immunol 16:343-53
Foxman, Ellen F; Storer, James A; Fitzgerald, Megan E et al. (2015) Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells. Proc Natl Acad Sci U S A 112:827-32
Hayashi, Kachiko; Sasai, Miwa; Iwasaki, Akiko (2015) Toll-like receptor 9 trafficking and signaling for type I interferons requires PIKfyve activity. Int Immunol 27:435-45
Iijima, Norifumi; Iwasaki, Akiko (2015) Tissue instruction for migration and retention of TRM cells. Trends Immunol 36:556-64

Showing the most recent 10 out of 58 publications