Mucosal surfaces are in contact with the external environment and protect the body from
infection by various microbes. To prevent
infectious diseases at the first line of defense, the establishment of pathogen-specific mucosal immunity by mucosal
vaccine delivery is needed.
Curdlan, a 1,3-β-glucan has a strong immunostimulatory effect when delivered as a
vaccine adjuvant. Here, we investigated whether
intranasal administration of
curdlan and
antigen (Ag) could induce sufficient mucosal immune responses and protect against
viral infections. Intranasal co-administration of
curdlan and OVA increased OVA-specific
IgG and
IgA Abs in both serum and mucosal secretions. In addition, intranasal co-administration of
curdlan and OVA induced the differentiation of OVA-specific Th1/Th17 cells in the draining lymph nodes. To investigate the protective immunity of
curdlan against
viral infection, intranasal co-administration of
curdlan with recombinant VP1 of EV71 C4a was administered and showed enhanced protection against enterovirus 71 in a passive serum transfer model using neonatal hSCARB2 mice, although
intranasal administration of VP1 plus
curdlan increased VP1-specific helper T cells responses but not mucosal
IgA. Next, Mongolian gerbils were intranasally immunized with
curdlan plus VP1, and they had effective protection against EV71 C4a
infection, while decreasing
viral infection and tissue damage by inducing Th17 responses. These results indicated that intranasal
curdlan with Ag improved Ag-specific protective immunity by enhancing mucosal
IgA and Th17 against
viral infection. Our results suggest that
curdlan is an advantageous candidate as a mucosal adjuvant and delivery vehicle for the development of mucosal
vaccines.