Persistent viral infections represent a significant public health problem with hundreds of millions of people infected. However, therapies that enable the host to purge these infections have been unsuccessful due to a limited understanding of the cellular and molecular mechanisms that promote virus persistence. Over the last decade studies have demonstrated that persistent viruses take advantage of negative immune regulatory molecules (IL-10, PD-1) to suppress the antiviral CD4 and CD8 T cell responses, resulting in T cell exhaustion, enabling virus persistence. Deletion of several immune stimulatory molecules such as IL-6 and IL- 21 result in lifelong virus persistence, suggest that the balance between negative and positive immune regulators determines virus clearance or persistence. Importantly, molecules such as IL-6 and IL-21 have known T follicular helper cell (TFH) and B cell stimulatory capacities and depletion of these molecules in vivo results in reduced TFH, B cell responses and antibody production. In fact, studies in humans have demonstrated that although TFH and germinal center (GC) B cells are generated during human persistent virus infection, their function is impaired. Despite the above findings, the mechanisms that restrain/promote optimal TFH, B and antibody responses during persistent virus infection are incompletely understood. We recently made the unexpected finding that during persistent LCMV infection IFN-I signaling was essential to promoting (rather than preventing) virus persistence. Importantly, IFN-I signaling supported induction of negative immune regulators (NIR) IL-10 and PD-L1, immune suppression, T cell exhaustion and lymphoid tissue destruction. Following up our published studies we now report that blockade of IFN-I signaling results in enhanced TFH, GC and plasma B cell responses. Thus we hypothesize IFN-I signaling restrains antiviral humoral immunity during persistent virus infection. The ultimate goal of this proposal is to generate a detailed understanding how IFN-I signaling modulates immune responses during persistent virus infection. The output of our studies should be a detailed cellular and molecular understanding how IFN-I regulates anti-viral humoral and cellular immune responses during persistent virus infection. In this project will use anti-IFNAR1 neutralizing antibodies, genetic and biochemical tools to determine how IFNAR1 signaling regulates TFH, GC and plasma B cell responses during a model persistent virus infection. This proposal encompasses important basic and potentially translational research goals - 1) to understand the mechanisms by which IFNAR1 signaling suppresses immune cell function; 2) discover IFN-I regulated cellular and biochemical pathways that promote virus persistence; and 3) leverage this knowledge to instruct future development of therapeutic modalities to promote immune responses to control of human persistent viral infection.
Persistent viral infections (such as HIV, HCV and HBV) represent a significant public health problem across the globe with hundreds of millions of people currently infected. Here we report that IFN-I blockade following persistent LCMV infection increases numbers of TFH, GC B and plasma cells following persistent virus infection, leading to enhanced control. We propose in this grant to determine the cellular subsets and signaling pathways downstream of IFN-I signaling that prevent virus control of persistent virus infection; the final goal of our studies is to leverage knowledge gained to aid development of therapeutic modalities to promote control of human persistent viral infections.
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