Mucosally DeliveredSalmonellaLive Vector Vaccines Elicit Potent Immune Responses against a Foreign Antigen in Neonatal Mice Born to Naive and Immune Mothers

Abstract

The development of effective vaccines for neonates and very young infants has been impaired by their weak, short-lived, and Th-2 biased responses and by maternal antibodies that interfere with vaccine take. We investigated the ability of Salmonella enterica serovars Typhi and Typhimurium to mucosally deliver tetanus toxin fragment C (Frag C) as a model antigen in neonatal mice. We hypothesize that Salmonella, by stimulating innate immunity (contributing to adjuvant effects) and inducing Th-1 cytokines, can enhance neonatal dendritic cell maturation and T-cell activation and thereby prime humoral and cell-mediated immunity. We demonstrate for the first time that intranasal immunization of newborn mice with 10 9 CFU of S. enterica serovar Typhi CVD 908-htrA and S. enterica serovar Typhimurium SL3261 carrying plasmid pTETlpp on days 7 and 22 after birth elicits high titers of Frag C antibodies, previously found to protect against tetanus toxin challenge and similar to those observed in adult mice. Salmonella live vectors colonized and persisted primarily in nasal tissue. Mice vaccinated as neonates induced Frag C-specific mucosal and systemic immunoglobulin A (IgA)-and IgG-secreting cells, T-cell proliferative responses, and gamma interferon secretion. A mixed Th1-and Th2-type response to Frag C was established 1 week after the boost and was maintained thereafter. S. enterica serovar Typhi carrying pTETlpp induced Frag C-specific antibodies and cell-mediated immunity in the presence of high levels of maternal antibodies. This is the first report that demonstrates the effectiveness of Salmonella live vector vaccines in early life.

Neonatal Immunization with a Sindbis Virus-DNA Measles Vaccine Induces Adult-Like Neutralizing Antibodies and Cell-Mediated Immunity in the Presence of Maternal Antibodies

“…Single cell suspension from spleens was prepared as previously described (30). To harvest BM cells, skin-peeled hind legs were removed and the bone cavity of femurs and tibiae were flushed with 3-5 ml of complete RPMI medium; cells centrifuged and resuspended in complete medium.…”

“…To harvest BM cells, skin-peeled hind legs were removed and the bone cavity of femurs and tibiae were flushed with 3-5 ml of complete RPMI medium; cells centrifuged and resuspended in complete medium. The frequency of IgG ASC were measured as previously described (30). Briefly, microtiter plates were coated with 5 g/ml MV lysate, washed with PBS, and blocked with complete medium.…”

“…Spleens were harvested on days 15 and 70 after birth, and single cell suspensions were prepared as previously described (30). Cells (5 ϫ 10 5 to 6.25 ϫ 10 4 ) were incubated with MV lysate (10 g/ml) in MultiScreen-HA 96-well nitrocellulose plates (Millipore) previously coated with 5 g/ml anti-mouse IFN-␥ (BD Pharmingen) and blocked with complete RPMI medium.…”

“…Cell proliferation was measured by incorporation of [ 3 H]thymidine as previously described (30). Results are expressed as stimulation index, calculated as counts per minute in cells incubated with Ag per counts per minute of cells incubated with medium alone Ϯ SEM of replicate cultures.…”

Mucosal delivery of bacterial antigens and CpG oligonucleotides formulated in biphasic lipid vesicles in pigs

“…19 The presence of antigen-specifi c antibodies in the mucosa may be due to local production by antibody-secreting cells (IgA) or through transudation of circulating immunoglobulin from the sera (IgG or IgA). In general, mucosal IgG is thought to be transudative, 20 although Gockel et al 21 showed local production of IgG after topical administration of There are clear advantages to using noninvasive vaccine delivery methods. Since many immunizations in the past were s.c., the boost injections could be avoided by i.n.…”