Abstract
Cholera toxin B subunit (CTB) was investigated as a classical mucosal adjuvant that can increase vaccine immunogenicity. In this study, we found out the in vitro efficacy of cholera toxin B subunit (CTB) in activating mice bone marrow-derived dendritic cells (BMDCs) through Toll-like receptor signaling pathways. In vitro RNA and transcriptional level profiling arrays revealed that CTB guides high levels of Th1 and Th2 type cytokines, inflammatory cytokines, and chemokines. Based on the robustness of these profiling results, we examined the induction of HIV Env-specific immunity by CTB co-inoculated with HIV Env DNA vaccine intramuscularly in vivo. CTB enhanced HIV-Env specific cellular immune responses in Env-specific IFN-γ ELISPOT, compared with DNA vaccine alone. Moreover, CTB induced high levels of Env specific humoral response and promoted antibody maturation after the third round of vaccination. This combination immunization strategy induced a Th2-type bias response which is indicative of a high ratio of IgG1/IgG2a. This study reports that CTB as a classical mucosal adjuvant could enhance HIV-1 DNA-based vaccine immunogenicity intramuscularly; therefore, these findings suggest that CTB could serve as an effective candidate adjuvant for DNA vaccination.
Disclosure of Potential Conflicts of Interest
No potential conflicts of interest were disclosed.
Acknowledgments
The authors are grateful to Dr Wenjun Zhang, Dr Zheng Liu, Dawei Ling, and Ying Liu for their assistance in animal experiments, and Dr Lena Yao for their critical reading and correcting of the manuscript. This work was supported by National Major projects for Infectious Diseases Control and Prevention (2012ZX10001008); National Natural Science Foundation of China (81020108030); SKLID Development grant (2008SKLID101).