A vaccine platform targeting lung-resident memory CD4⁺ T-cells provides protection against heterosubtypic influenza infections in mice and ferrets.

Abstract

Lung tissue-resident memory T (T_RM) cells induced by influenza vaccination are crucial for heterosubtypic immunity upon re-exposure to the influenza virus, enabling rapid and robust responses upon reactivation. To enhance the efficacy of influenza vaccines, we induce the generation of lung T_RM cells following intranasal vaccination with a commercial influenza vaccine adjuvanted with NexaVant (NVT), a TLR3 agonist-based adjuvant. We demonstrate that intranasal immunization with the NVT-adjuvanted vaccine provides improved protection against influenza virus infections by inducing the generation of CD4⁺ T_RM cells in the lungs in a type I interferon-dependent manner. These pulmonary CD4⁺ T_RM cells provide potent mucosal immunity and cross-protection against heterosubtypic infections in both mouse and ferret models. This vaccine platform has the potential to significantly improve conventional intramuscular influenza vaccines by providing broader protection.