
<ArticleTitle>Recombinant Norwalk <prot>virus-like particle</prot>s administered intranasally to mice induce systemic and mucosal (fecal and vaginal) immune responses.</ArticleTitle>
<AbstractText>Recombinant Norwalk <prot>virus-like particle</prot>s (rNV <prot>VLP</prot>s) were administered to BALB/c mice by the intranasal (i.n.) route to evaluate the induction of mucosal antibody responses. The results were compared to systemic and mucosal responses observed in new and previous studies (J. M. Ball, M. E. Hardy, R. L. Atmar, M. E. Connor, and M. K. Estes, J. Virol. 72:1345-1353, 1998) after oral administration of rNV <prot>VLP</prot>s. Immunizations were given in the presence or absence of a mucosal adjuvant, mutant Escherichia coli heat-labile toxin LT(R192G). rNV-specific <prot>immunoglobulin G</prot> (<prot>IgG</prot>) and fecal <prot>IgA</prot> were evaluated by enzyme-linked immunosorbent assay. The i.n. delivery of rNV <prot>VLP</prot>s was more effective than the oral route at inducing serum <prot>IgG</prot> and fecal <prot>IgA</prot> responses to low doses of rNV particles. Vaginal responses of female mice given <prot>VLP</prot>s by the i.n. and oral routes were also examined. All mice that received two immunizations with low doses i.n. (10 or 25 microg) of rNV <prot>VLP</prot>s and the majority of mice that received two high doses orally (200 microg) in the absence of adjuvant had rNV-specific serum <prot>IgG</prot>, fecal, and vaginal responses. Additional experiments evaluated whether rNV <prot>VLP</prot>s can function as a mucosal adjuvant by evaluating the immune responses to two soluble proteins, <prot>keyhole limpet hemocyanin</prot> and chicken <prot>egg albumin</prot>. Under the conditions tested, rNV <prot>VLP</prot>s did not enhance the serum <prot>IgG</prot> or fecal <prot>IgA</prot> response to these soluble proteins when coadministered by the i.n. or oral route. Low doses of nonreplicating rNV <prot>VLP</prot>s are immunogenic when administered i.n. in the absence of adjuvant, and addition of adjuvant enhanced the magnitude and duration of these responses. Recombinant NV <prot>VLP</prot>s represent a candidate mucosal vaccine for NV infections in humans.</AbstractText>
