Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

BACKGROUND: Oral vaccination with live-attenuated Salmonella Typhi strain Ty21a is modestly efficacious, but the mechanisms of protection are currently unknown. While humoral and cellular immune responses are well described in peripheral blood, the cellular response at the intestinal mucosa has never been directly assessed. METHODS: We vaccinated healthy adults with Ty21a and assessed humoral and cellular immunity in vaccinated volunteers and controls after 18 days. Immunoglobulin levels were assessed in peripheral blood by an enzyme-linked immunosorbent assay. Cellular responses were assessed in peripheral blood and at the duodenal and colonic mucosa by flow cytometry. RESULTS: We demonstrate the generation of Ty21a-responsive and heterologous influenza virus-responsive CD4(+) and CD8(+) T cells at the duodenal mucosa. All duodenal responses were consistently correlated, and no responses were observed at the colonic mucosa. Peripheral anti-lipopolysaccharide immunoglobulin G and immunoglobulin A responses were significantly correlated with duodenal responses. The assessment of integrin β7 expression intensity among peripheral and duodenal T-cell subsets revealed varied capacities for mucosal homing and residence. CONCLUSIONS: The breadth of duodenal cellular responses was not reflected peripherally. The direct evaluation of mucosal immune defense may yield functional correlates of protection and could provide insight into mechanisms that may be manipulated to enhance vaccine immunogenicity.

Original publication




Journal article


J Infect Dis

Publication Date





1809 - 1819


Salmonella, T cells, Ty21a, cellular immunity, cytokines, heterologous immunity, humoral immunity, immunoglobulins, typhoid, Administration, Oral, Adult, Antibodies, Bacterial, CD4-Positive T-Lymphocytes, CD8-Positive T-Lymphocytes, Enzyme-Linked Immunosorbent Assay, Female, Humans, Immunity, Cellular, Immunity, Humoral, Immunogenicity, Vaccine, Intestinal Mucosa, Male, Orthomyxoviridae, Polysaccharides, Bacterial, Salmonella typhi, Typhoid-Paratyphoid Vaccines, Vaccines, Attenuated, Young Adult