RSV-specific T cell epitope presentation in the respiratory tract differs between adults and neonates as revealed by a novel T cell proliferation assay

Abstract Respiratory syncytial virus (RSV) invades the respiratory epithelium and provokes severe symptoms in young children leading to infant mortality. CD8 tissue resident memory (TRM) cells are associated with protection in adults against RSV, but are poorly established in neonatal mice consequent to primary infection. We hypothesized that antigen presentation contributes to age-dependent TRM establishment, thus we sought to define antigen kinetics in RSV-infected adult and neonatal mice. CB6F1/J adult and neonatal mice were infected with RSV and lung tissue were isolated over the course of acute and convalescent infection. Single cell lung suspension was co-cultured in vitrowith RSV K dM2 82–90(M2) or D bM 187–195(M) epitope-specific T cells isolated from CD8 T cell receptor (TCR) transgenic mice. T cells were stained with carboxyfluorescein succinimidyl ester (CFSE) to quantify proliferative response 48 hours post-incubation at 37°C via flow cytometry. From lung tissue isolated at 7 days post infection (dpi), M and M2-specific CD8 T cells proliferated in response to co-culture; however, higher rates were induced by neonatal lung tissue primarily by M-specific T cells. By 8 and 9 dpi, proliferation induced by isolated neonatal lung continued while proliferation induced by adult lung tissue was not quantifiable by our assay. Our findings suggest antigen availability in neonates exceeds that of adults and is age and epitope-dependent. These discoveries indicate that antigen accessibility does not independentlycorrespond with the magnitude of the T cell response in early life. Exploring the inflammatory contributions to RSV-specific T cell defenses is required as this may aid in vaccine design and understanding disease pathogenesis. Supported by grant from NIH R01-AI154619.