Increased mRNA expression of interferon-induced Mx1 and immunomodulation following oral administration of IFN-alpha2b-transformed B. longum to mice.

We previously constructed an arabinose-inducible recombinant Bifidobacterium longum that could efficiently express secreted IFN-alpha2b in vitro (Deng et al. in Arch Microbiol 191:681-686, 2009). Here, we investigated the influence of oral pBAD-SPIFN-transformed B. longum on immunomodulation and IFN-induced Mx1 gene transcription in mice. We observed enhanced serum and fecal IFN-alpha2b concentrations in mice orally administered recombinant B. longum, suggesting a possible Th1 pattern of induction in the spleen and Peyer's patches. Transcription of the typically IFN-induced antiviral Mx1 gene in the hepatic and intestinal tissues of these mice was also markedly enhanced. In conclusion, oral administration of the recombinant B. longum expressing IFN-alpha2b might play its roles in the immunomodulation of the mice, and the potential clinical value of this bacterium in the treatment of viral infections needs to be further studied.