Mucosal Immunol. 2026 Aug 24:100401. doi: 10.1016/j.mucimm.2026.100401. Online ahead of print.
ABSTRACT
Infants require repeated immunizations of injectable-type vaccines against different pathogens because their immune systems are weaker than those of adults. However, these injectable vaccines cause physical and psychological discomfort. Therefore, there is an urgent need to develop pain-free mucosal vaccines that are optimized for immunologically immature infants. Using an infant murine model, we examined the effectiveness of an intranasal norovirus virus-like-particle (VLP) vaccine with zymosan as an adjuvant. The intranasal immunization of infant mice with VLPs alone induced mucosal and systemic VLP-specific immune responses that were substantially weaker than those of adults. In contrast, infant mice administered a minimum dose of intranasal zymosan-adjuvanted VLP vaccine showed increased levels of intestinal and salivary VLP-specific IgA antibodies, as well as plasma VLP-specific IgG antibodies, at levels comparable to those in adults. Importantly, intestinal and salivary antibodies elicited by intranasal immunization with the zymosan-adjuvanted VLP vaccine effectively inhibited norovirus propagation in human-induced pluripotent stem cellderived intestinal epithelial cells. These findings suggest that the intranasal zymosan-adjuvanted norovirus VLP vaccine is an effective mucosal vaccine candidate for infants. It may help reduce the pain associated with injections and the number of immunizations infants required to achieve sufficient protective immunity against norovirus.
PMID:42637083 | DOI:10.1016/j.mucimm.2026.100401