The bacterial second messenger cyclic diGMP exhibits potent adjuvant properties

The identification of new adjuvants is a critical need in vaccinology. In this work, it is demonstrated that bis-(3',5')-cyclic dimeric guanosine monophosphate (cdiGMP) exhibits potent adjuvant properties. Subcutaneous co-administration of cdiGMP with P-galactosidase (P-Gal) to mice resulted in the elicitation of significantly higher antigen-specific serum IgG titres than in animals receiving P-Gal alone. Strong cellular immune responses, which were characterized by a balanced Th1/Th2 pattern, were also observed in response to the P-Gal protein and a peptide encompassing its MHC class I-restricted epitope in immunized animals. These results suggest that cdiGMP represents a promising adjuvant for vaccine development. (c) 2006 Elsevier Ltd. All rights reserved.