A TLR7/8 Agonist-Including DOEPC-Based Cationic Liposome Formulation Mediates Its Adjuvanticity Through the Sustained Recruitment of Highly Activated Monocytes in a Type I IFN-Independent but NF-κB-Dependent Manner.

Novel adjuvants, such as Toll-like receptors (TLRs) agonists, are needed for the development of new formulations able to circumvent limitations of current vaccines. Among TLRs, TLR7/8 agonists represent promising candidates, as they are well described to enhance antigen-specific antibody responses and skew immunity toward T helper (TH) 1 responses. We find here that the incorporation of the synthetic TLR7/8 ligand 3M-052 in a cationic DOEPC-based liposome formulation shifts immunity toward TH1 responses and elicits strong and long-lasting germinal center and follicular T helper cell responses in adult mice. This reflects the prolonged recruitment of innate cells toward the site of immunization and homing of activated antigen-loaded monocytes and monocyte-derived dendritic cells toward draining lymph nodes. We further show that this adjuvanticity is independent of type I IFN but NF-κB-dependent. Overall, our data identify TLR7/8 agonists incorporated in liposomes as promising and effective adjuvants to enhance TH1 and germinal center responses.

Safety and immunogenicity of a candidate bioconjugate vaccine against Shigella dysenteriae type 1 administered to healthy adults: A single blind, partially randomized Phase I study.

BACKGROUND: Shigellae cause severe disease in endemic countries, especially in children. Several efficacy trials have been conducted with candidate vaccines against Shigellae, but the lack of protection, the safety concerns, or manufacturing challenges hindered successful market approval. Conjugated vaccines have been shown to be safe and effective for different pathogens (i.e., Neisseria meningitidis, Shigella pneumonia, Haemophilus influenzae). The bio-conjugation technology, exploited here for the Shigella dysenteriae candidate vaccine, offers a novel and potentially simpler way to develop and produce vaccines against one of the major causes of morbidity and mortality in developing countries. METHODS: A novel S. dysenteriae bioconjugate vaccine (GVXN SD133) made of the polysaccharide component of the Shigella O1 lipopolysaccharide, conjugated to the exotoxin protein A of Pseudomonas aeruginosa (EPA), was evaluated for immunogenicity and safety in healthy adults in a single blind, partially randomized Phase I study. Forty subjects (10 in each dose group; 2 µg or 10 µg with or without aluminium adjuvant) received two injections 60 days apart and were followed-up for 150 days. RESULTS: Both doses and formulations were well tolerated; the safety and reactogenicity profiles were consistent with that of other conjugated vaccines, adjuvanted or not, independent of the dose and the number of injections. The GVXN SD133 vaccine elicited statistically significant O1 specific humoral responses at all time points in all vaccination groups. Between-group comparisons did not show statistically significant differences in geometric mean titers of immunoglobulin G and A at any post-vaccination time point. CONCLUSIONS: This study demonstrated that the GVXN SD133 vaccine has a satisfactory safety profile. It elicited a significant humoral response to Shigella O1 polysaccharides at all doses tested. The protein carrier also elicited functional antibodies, showing the technology's advantages in preserving both sugar and conjugated protein epitopes. This trial is registered at ClinicalTrials.gov (NCT01069471).

Safety and immunogenicity of rts,s+trap malaria vaccine, formulated in the as02a adjuvant system, in infant rhesus monkeys.

Malaria vaccine RTS,S combined with thrombospondin-related anonymous protein (TRAP) and formulated with AS02A (RTS,S+TRAP/AS02A) is safe and immunogenic in adult humans and rhesus monkeys (Macaca mulatta). Here, RTS,S+TRAP/AS02A was administered on a 0-, 1-, and 3-month schedule to three cohorts of infant monkeys, along with adult comparators. Cohort 1 evaluated 1/5, 1/2, and full adult doses, with the first dose administration at one month of age; cohort 2 monkeys received full adult doses, with the first dose administration at one versus three months of age; and, cohort 3 compared infants gestated in mothers with or without previous RTS,S/AS02A immunization. Immunization site reactogenicity was mild. Some infants, including the phosphate-buffered saline only recipient, developed transient iron-deficiency anemia, which is considered a result of repeated phlebotomies. All RTS,S+TRAP/AS02A regimens induced vigorous antibody responses that persisted through 12 weeks after the last vaccine dose. Modest lymphoproliferative and ELISPOT (interferon-gamma and interleukin-5) responses, particularly to TRAP, approximated adult comparators. RTS,S+TRAP/AS02A was safe and well tolerated. Vigorous antibody production and modest, selective cell-mediated immune responses suggest that RTS,S+TRAP/AS02A may be immunogenic in human infants.