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- Title
Myeloid cell tropism enables MHC-E–restricted CD8<sup>+</sup> T cell priming and vaccine efficacy by the RhCMV/SIV vaccine.
- Authors
Hansen, Scott G.; Hancock, Meaghan H.; Malouli, Daniel; Marshall, Emily E.; Hughes, Colette M.; Randall, Kurt T.; Morrow, David; Ford, Julia C.; Gilbride, Roxanne M.; Selseth, Andrea N.; Trethewy, Renee Espinosa; Bishop, Lindsey M.; Oswald, Kelli; Shoemaker, Rebecca; Berkemeier, Brian; Bosche, William J.; Hull, Michael; Silipino, Lorna; Nekorchuk, Michael; Busman-Sahay, Kathleen
- Abstract
The strain 68-1 rhesus cytomegalovirus (RhCMV)–based vaccine for simian immunodeficiency virus (SIV) can stringently protect rhesus macaques (RMs) from SIV challenge by arresting viral replication early in primary infection. This vaccine elicits unconventional SIV-specific CD8+ T cells that recognize epitopes presented by major histocompatibility complex (MHC)–II and MHC-E instead of MHC-Ia. Although RhCMV/SIV vaccines based on strains that only elicit MHC-II– and/or MHC-Ia–restricted CD8+ T cells do not protect against SIV, it remains unclear whether MHC-E–restricted T cells are directly responsible for protection and whether these responses can be separated from the MHC-II–restricted component. Using host microRNA (miR)–mediated vector tropism restriction, we show that the priming of MHC-II and MHC-E epitope–targeted responses depended on vector infection of different nonoverlapping cell types in RMs. Selective inhibition of RhCMV infection in myeloid cells with miR-142–mediated tropism restriction eliminated MHC-E epitope–targeted CD8+ T cell priming, yielding an exclusively MHC-II epitope–targeted response. Inhibition with the endothelial cell–selective miR-126 eliminated MHC-II epitope–targeted CD8+ T cell priming, yielding an exclusively MHC-E epitope–targeted response. Dual miR-142 + miR-126–mediated tropism restriction reverted CD8+ T cell responses back to conventional MHC-Ia epitope targeting. Although the magnitude and differentiation state of these CD8+ T cell responses were generally similar, only the vectors programmed to elicit MHC-E–restricted CD8+ T cell responses provided protection against SIV challenge, directly demonstrating the essential role of these responses in RhCMV/SIV vaccine efficacy. RhCMV tropism determines unconventional response: CMV-based vaccine vectors for simian immunodeficiency virus (RhCMV/SIV) lead to profound protection against SIV in rhesus macaques (RMs). This protection is related to the induction of MHC-II– and MHC-E–targeting CD8+ T cells, but it is unclear how these unconventional cells are primed and which are needed for protection. Here, Hansen et al. used microRNAs to limit the ability of RhCMV/SIV vectors to replicate in various cell types. They found that limiting RhCMV/SIV vaccine replication in myeloid cells abrogated the induction of MHC-E–restricted T cells and protection against SIV of in RMs. These data suggest that the unconventional, MHC-E–restricted CD8+ T cells induced by RhCMV/SIV are critical for protection against SIV.
- Publication
Science Immunology, 2022, Vol 7, Issue 72, p1
- ISSN
2470-9468
- Publication type
Article
- DOI
10.1126/sciimmunol.abn9301