# Non-canonical epitope presentation and antigen processing by MHC-E

> **NIH NIH R01** · OREGON HEALTH & SCIENCE UNIVERSITY · 2024 · $701,712

## Abstract

Project Summary
In the course of developing cytomegalovirus (CMV) as a new vaccine platform for eliciting effector differentiated
T cell immunity, we observed that rhesus CMV (RhCMV) expressing simian immunodeficiency (SIV) antigens
elicit immune responses that control and ultimately clear highly pathogenic SIV. Surprisingly however, protection
was only observed with genetically modified vectors eliciting CD8+ T cells restricted by non-polymorphic, highly
conserved MHC-E instead of classical MHC-I. Targeting HIV peptides presented by HLA-E thus represents a
novel, unexpected and unconventional approach to AIDS vaccine development that has recently entered the
clinical phase. However, we have only a very limited understanding of the molecular mechanisms that render
CMV the only vaccine vector capable of eliciting these unconventional responses to any antigen and that render
lentivirus-infected cells vulnerable to T cell control. Our findings that MHC-E presents a wide variety of antigens
is unexpected because MHC-E predominantly binds the nonameric VMAPRTL(L,I,V,F)L (VL9) self-peptide
contained in the cleavable leader sequence of MHC-I. Here, our goal is to elucidate how MHC-E is loaded with
diverse non-canonical peptides in uninfected cells or in cells infected with HIV or CMV in vitro and to identify the
RhCMV-infected cells and molecular mechanisms required for the priming of MHC-E restricted CD8+ T cells in
vivo. These objectives will be accomplished by an international team of investigators with relevant experience.
Aim 1 is to use a unique set of MHC-E/peptide specific reagents to monitor MHC-E peptide loading and
presentation by myeloid and HIV-infected cells upon inhibiting specific cellular proteins and pathways. Cellular
targets will be selected from hits of preliminary CRISPR/cas9 screens or based on their known function in
vesicular traffic or peptide loading of classical MHC molecules. In aim 2, we will investigate how the extensive
reorganization of intracellular vesicular structures observed in CMV-infected cells contributes to the loading of
MHC-E with non-canonical peptides. A particular emphasis will be on the role of viral microRNAs which redirect
vesicular traffic by targeting vesicular sorting proteins and which seem to be required for MHC-E restricted T cell
stimulation by CMV-infected cells. The role of viral microRNAs as well as selected host pathways for the induction
of these T cells in vivo will be examined in aim 3. This will be accomplished by generating recombinant RhCMV
lacking microRNAs or expressing host gene-targeting small hairpin RNAs. Since recent results suggest that
priming of MHC-E restricted T cells requires infection of myeloid cells expressing micro-RNA142, we will identify
the infected cell type and characterize neighboring T cells by combining sophisticated imaging and spatial
transcriptomic techniques. We expect that the results of this research will impact basic and translational
immunology including ...

## Key facts

- **NIH application ID:** 10935982
- **Project number:** 5R01AI175459-02
- **Recipient organization:** OREGON HEALTH & SCIENCE UNIVERSITY
- **Principal Investigator:** Klaus J Fruh
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $701,712
- **Award type:** 5
- **Project period:** 2023-09-25 → 2028-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10935982

## Citation

> US National Institutes of Health, RePORTER application 10935982, Non-canonical epitope presentation and antigen processing by MHC-E (5R01AI175459-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10935982. Licensed CC0.

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