Insights into HLA-Restricted T Cell Responses in a Novel Mouse Model of Dengue Virus Infection Point toward New Implications for Vaccine Design

Abstract

The frequency of dengue virus (DENV) infection has increased dramatically in the last few decades, and the lack of a vaccine has led to significant morbidity and mortality worldwide. To date, a convenient murine system to study human T cell responses to DENV has not been available. Mice transgenic for human leukocyte antigens (HLA) are widely used to model human immune responses and it has been shown that mouse-passaged DENV is able to replicate to significant levels in IFN-α/βR−/− mice. To cover a wide range of HLA phenotypes, we backcrossed IFN-α/βR−/− mice with HLA A*0201, A*0101, A*1101, B*0702 and DRB1*0101 transgenic mice. A DENV proteome-wide screen identified a total of 42 epitopes across all HLA-transgenic IFN-α/βR−/− strains tested. In contrast only 8 of these elicited responses in the corresponding IFN-α/βR+/+ mice. We were able to identify T cell epitopes from 9 out of the 10 DENV proteins. However, the majority of responses were derived from the highly conserved nonstructural proteins NS3 and NS5. The relevance of this model is further demonstrated by the fact that most of the epitopes identified in our murine system are also recognized by PBMC from DENV exposed human donors, and a dominance of HLA B*0702 restricted responses has been detected in both systems. Our results provide new insights into HLA-restricted T cell responses against DENV, and we herein describe a novel murine model, which allows the investigation of T cell-mediated immune mechanisms relevant to vaccine design.

Cytomegalovirus-Specific CD4 T Cells Are Cytolytic and Mediate Vaccine Protection

“…Enzyme-linked immunospot (ELISPOT) assays were performed as described previously (35). For CD4 T cell intracellular cytokine staining (ICCS) of spleen, liver, or lung cells, 1 ϫ 10 6 cells were incubated with 5 g/ml of m53 285-299 or m78 417-431 15-mer peptides for 8 h or treated with phorbol myristate acetate (PMA) (100 ng/ml) and ionomycin (500 ng/ml) for 5 h in the presence of brefeldin A (2 g/ml).…”

Gamma Interferon (IFN-γ) Receptor Restricts Systemic Dengue Virus Replication and Prevents Paralysis in IFN-α/β Receptor-Deficient Mice

“…Perhaps DENV's extreme susceptibility to the murine type I IFN-signaling pathway (33,34), the molecules of which differ sufficiently from human analogues to prevent DENV-mediated inhibition (3), limits extraneural antigen availability and results in a blunted cellular immune response. Accordingly, we have observed that the breadth and magnitude of DENV-specific T cell responses in wild-type mice are lower than in IFN-␣/␤ receptor-deficient mice (45,48,50). Combined with the immune-privileged status of the CNS and the capacity of DENV for infection of the CNS, a blunted T cell response may favor efficient DENV replication in the CNS.…”

Immunodominance Changes as a Function of the Infecting Dengue Virus Serotype and Primary versus Secondary Infection

“…Mice transgenic for HLA are widely used to study T cell responses restricted by human major histocompatibility complex (MHC) molecules (16)(17)(18), and it has been shown that mice lacking the alpha/beta interferon receptor (IFN-␣/␤R) support a productive DENV infection (19)(20)(21)(22). To cover a wide range of HLA phenotypes, we backcrossed IFN-␣/␤R Ϫ/Ϫ mice with HLA A*0201, A*0101, B*0701, B*4001, and DRB1*0101 single-alleletransgenic mice.…”