A team from Maryland, USA, evaluated the clinical safety and immunogenicity of a recombinant subunit vaccine against enterotoxigenic Escherichia coli (ETEC), administered transcutaneously.
Some 26 adult volunteers received patches containing the recombinant ETEC colonization factor CS6, either with heat-labile enterotoxin (LT), or patches containing CS6 alone.
The vaccine was administered at 0, 1, and 3 months. Serum antibodies and antibody-secreting cells (ASCs) were assessed.
It was found that there were no responses to CS6 in the absence of LT.
In the groups receiving both CS6 and LT, 68% and 53% were found to have serum anti-CS6 immunoglobulin G (IgG) and IgA, respectively. In addition, 37% and 42% had IgG and IgA anti-CS6 antibody-secreting cells.
All of the volunteers receiving LT had anti-LT IgG and 90% had serum anti-LT IgA. Some 79% and 37% had anti-LT IgG and IgA antibody-secreting cells.
| Antigens delivered by a patch induced systemic immune responses.
| Infection and Immunity |
Delayed-type hypersensitivity, suggesting T-cell responses, was seen in 14 of 19 volunteers receiving both LT and CS6
No delayed-type hypersensitivity was seen in subjects receiving CS6 alone.
Fernando Güereña-Burgueño, of the Naval Medical Research Center, Silver Spring, Maryland, said on behalf of his team, "This study demonstrated that protein antigens delivered by a simple patch could induce significant systemic immune responses, but only in the presence of an adjuvant such as LT."
"The data suggest that an ETEC vaccine for travelers delivered by a patch may be a viable approach worthy of further evaluation," he concluded.