Vitamin A deficiency impairs the immune response to intranasal vaccination and RSV infection in neonatal calves

Respiratory syncytial virus (RSV) infection is a leading cause of severe acute lower respiratory tract infection in infants and children worldwide. Vitamin A deficiency (VAD) is one of the most prevalent nutrition-related health problems in the world and is a significant risk factor in the development of severe respiratory infections in infants and young children. Bovine RSV (BRSV) is a primary cause of lower respiratory tract disease in young cattle. The calf model of BRSV infection is useful to understand the immune response to human RSV infection. We have previously developed an amphiphilic polyanhydride nanoparticle (NP)-based vaccine (i.e., nanovaccine) encapsulating the fusion and attachment proteins from BRSV (BRSV-NP). Calves receiving a single, intranasal dose of the BRSV-NP vaccine are partially protected from BRSV challenge. Here, we evaluated the impact of VAD on the immune response to the BRSV-NP vaccine and subsequent challenge with BRSV. Our results show that VAD calves are unable to respond to the mucosal BRSV-NP vaccine, are afforded no protection from BRSV challenge and have significant abnormalities in the inflammatory response in the infected lung. We further show that acute BRSV infection negatively impacts serum and liver retinol, rendering even well-nourished individuals susceptible to VAD. Our results support the use of the calf model for elucidating the impact of nutritional status on mucosal immunity and respiratory viral infection in infants and underline the importance of VA in regulating immunity in the respiratory mucosa.