Lentiviral vectors (LVs) are highly efficient at inducing CD8 + T cell responses. However, LV-encoded antigens are processed inside the cytosol of antigen-presenting cells, which does not directly communicate with the endosomal major histocompatibility complex class II (MHC-II) presentation pathway. LVs are thus poor at inducing CD4 + T cell response. To overcome this limitation, we devised a strategy whereby LV-encoded antigens are extended at their N-terminal end with the MHC-II-associated light invariant chain (li), which contains an endosome-targeting signal sequence. When evaluated with an LV-encoded polyantigen composed of CD4 + T cell targets from Mycobacterium tuberculosis, intranasal vaccination in mice triggers pulmonary polyfunctional CD4 + and CD8 + T cell responses. Adjuvantation of these LVs extends the mucosal immunity to Th17 and Tc17 responses. A systemic prime and an intranasal boost with one of these LV induces protection against M. tuberculosis. This strategy improves the protective power of LVs against infections and cancers, where CD4 + T cell immunity plays an important role.
Competing Interests: Declaration of interests P.C. is the founder and CSO of TheraVectys. J.L., F.A., P.A., M.-W.K., F.M., and A.N. are employees of TheraVectys. J.L., F.A., C.B., F.M., L.M., and P.C. are inventors of a pending patent directed to LV immunization able to induce CD4(+) T cells.
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