Salmonella typhi Ty21a bacterial ghost vector augments HIV-1 gp140 DNA vaccine-induced peripheral and mucosal antibody responses via TLR4 pathway.

Because of their stability and ease of manipulation, DNA vaccines have considerable potential for eliciting immune responses. However, they are limited by their weak immunogenicity, especially in humans. To address this challenge, we explored a new strategy of HIV vaccine delivery using Salmonella typhi Ty21a bacterial ghosts (BGs). We found that Ty21a BGs loaded with an HIV gp140 DNA vaccine (Ty21a BG-DNA) were readily taken up by murine macrophage RAW264.7 cells, and gp140 was efficiently expressed in these cells. Peripheral and intestinal mucosal anti-gp120 antibody responses in mice vaccinated with BGs-DNA vaccine were significantly higher than those in mice immunized with naked DNA vaccine. The enhancement of antibody responses was associated with BG-induced production of IL-10 through TLR4 pathway. These results demonstrate that Ty21a BGs is a novel and effective delivery vehicle for DNA vaccines, which could therefore be used as a new strategy for development of HIV vaccines.