ABSTRACT
Breast milk confers multiple benefits to the neonate, including passive immunity against multiple microorganisms via Abs. However, it remains unclear whether breast milk-derived Abs affect vaccine-induced immunity in the neonate. We evaluated in C57BL/6 and BALB/c mice whether breastfeeding from an mRNA-SARS-CoV-2-vaccinated dam affects vaccine-induced immunity in neonate mice. Using an experimental model that allows the distinction of maternal Abs and neonate Abs based on their allotype, we show that breastfeeding from an immune dam is associated with reduced vaccine immunity in the neonate. Importantly, mice that breastfed from an immune dam showed reduced numbers of plasma cells after vaccination, relative to mice that breastfed from a naive dam. Our subsequent studies using an mRNA-luciferase reporter system show that passive transfer of Abs through breastfeeding accelerates the clearance of vaccine Ag in suckling mice, resulting in reduced Ag availability. Altogether, maternal Abs transferred through breast milk can protect against infectious microorganisms, but they may also interfere with the neonate's response to vaccination by accelerating the clearance of vaccine Ag. These findings are important for understanding the effects of maternal Abs on the neonate's response to vaccines and may provide insights for improving neonatal vaccines.
Subject(s)
Animals, Newborn , Immunity, Maternally-Acquired , Mice, Inbred BALB C , Milk, Human , Animals , Mice , Female , Immunity, Maternally-Acquired/immunology , Milk, Human/immunology , Animals, Suckling/immunology , Mice, Inbred C57BL , Vaccination , Humans , Breast FeedingABSTRACT
mRNA vaccines have demonstrated efficacy against COVID-19. However, concerns regarding waning immunity and breakthrough infections have motivated the development of next-generation vaccines with enhanced efficacy. In this study, we investigated the impact of 4-1BB costimulation on immune responses elicited by mRNA vaccines in mice. We first vaccinated mice with an mRNA vaccine encoding the SARS-CoV-2 spike antigen like the Moderna and Pfizer-BioNTech vaccines, followed by administration of 4-1BB costimulatory antibodies at various times post-vaccination. Administering 4-1BB costimulatory antibodies during the priming phase did not enhance immune responses. However, administering 4-1BB costimulatory antibodies after 96 hours elicited a significant improvement in CD8 T cell responses, leading to enhanced protection against breakthrough infections. A similar improvement in immune responses was observed with multiple mRNA vaccines, including vaccines against common cold coronavirus, human immunodeficiency virus (HIV), and arenavirus. These findings demonstrate a time-dependent effect by 4-1BB costimulation and provide insights for developing improved mRNA vaccines.
ABSTRACT
Viral vectors are being used for the treatment of cancer. Yet, their efficacy varies among tumors and their use poses challenges in immunosuppressed patients, underscoring the need for alternatives. We report striking antitumoral effects by a nonlytic viral vector based on attenuated lymphocytic choriomeningitis virus (r3LCMV). We show in multiple tumor models that injection of tumor-bearing mice with this vector results in improved tumor control and survival. Importantly, r3LCMV improved tumor control in immunodeficient Rag1-/- mice and MyD88-/- mice, suggesting that multiple pathways contributed to the antitumoral effects. The antitumoral effects of r3LCMV were also observed when this vector was administered several weeks before tumor challenges, suggesting the induction of trained immunity. Single-cell RNA sequencing analyses, antibody blockade experiments, and knockout models revealed a critical role for host-intrinsic IFN-I in the antitumoral efficacy of r3LCMV vectors. Collectively, these data demonstrate potent antitumoral effects by r3LCMV vectors and unveil multiple mechanisms underlying their antitumoral efficacy.
Subject(s)
Genetic Vectors , Interferon Type I , Lymphocytic choriomeningitis virus , Mice, Knockout , Animals , Lymphocytic choriomeningitis virus/immunology , Lymphocytic choriomeningitis virus/genetics , Mice , Interferon Type I/immunology , Interferon Type I/genetics , Myeloid Differentiation Factor 88/genetics , Myeloid Differentiation Factor 88/immunology , Humans , Cell Line, Tumor , Mice, Inbred C57BL , Neoplasms, Experimental/immunology , Neoplasms, Experimental/genetics , Neoplasms, Experimental/therapy , Neoplasms, Experimental/pathology , Homeodomain ProteinsABSTRACT
Viral vectors are being used for the treatment of cancer. Yet their efficacy varies among tumors and their use poses challenges in immunosuppressed patients, underscoring the need for alternatives. We report striking antitumoral effects by a nonlytic viral vector based on attenuated lymphocytic choriomeningitis virus (r3LCMV). We show in multiple tumor models that injection of tumor-bearing mice with this novel vector results in improved tumor control and survival. Importantly, r3LCMV also improved tumor control in immunodeficient Rag1-/- mice. Single cell RNA-Seq analyses, antibody blockade experiments, and KO models revealed a critical role for host IFN-I in the antitumoral efficacy of r3LCMV vectors. Collectively, these data demonstrate potent antitumoral effects by a replication-attenuated LCMV vector and unveil mechanisms underlying its antitumoral efficacy.