IgA response by oral infection with an attenuated Yersinia enterocolitica mutant: implications for its use as oral carrier vaccine.

Yersinia enterocolitica (Ye) mutant strain (sycH-) is unable to secrete the virulence protein YopH. Mucosal vaccination is often required to induce protection, but stimulating strong IgA response is frequently difficult. Here, we addressed whether Ye sycH- might induce IgA response, and investigated its attenuation in TNFRp55-/-, IL-12p40-/- and IL-4-/- mice. We found that Ye sycH- colonizes Peyer's patches, and induces higher Yersinia-specific IgA levels in feces and in serum compared with Ye wild type. The Ye sycH-mutant proved to be attenuated and induced IgA in both wild-type and immunodeficient mice. These lines of evidence show the attenuation of Ye sycH- and its ability to stimulate an IgA response. This mutant might be useful as an oral vaccine carrier.